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Comparison of Traditional Hawaiian and Modern Outrigger Canoe Manufacturing  
­  
 
Dept. of Mechanical Engineering   
University of Hawai'i at Mānoa 
 
 
 
 
Students:  Justin Dery     Advisor:   Dr. Jingjing Li, Ph. D. 
  Jeffrey Ibara   
  Mitch McLean  
William Segall 
   
  Holm Smidt     
  Joseph Valle     
 
 
 
 
Abstract:  
In this report, we will compare ancient Hawaiian canoe building to the modern                         
production of canoes. Comparing the materials used, the methods of construction, and the tools                           
at each builder’s disposal. It would be obvious to say that things have gotten better over time, but                                   
there are methods and components from ancient traditions that are still very much a part of how                                 
canoes are built today.  
 
 
   
 
1. Introduction  
As engineering students in Hawaii, it is hard not to notice the engineering solutions                           
produced by ancient Hawaiians. In a remarkable feat of achievement not seen elsewhere until                           
several hundred to thousands of years later, the ancient Hawaiians engineered, built, and                         
navigated vessels capable of traversing the vast expanse of the Pacific Ocean without the benefit                             
of metals[1]. 
In this paper, we aim to investigate the materials and manufacturing processes of the                           
ancient Hawaiian people, as well as detailing what improvements and advancements have been                         
made to canoe design, and how the modern design evolved from its traditional Hawaiian roots.  
 
1.1 The Outrigger Canoe  
A variety of canoe designs can be observed from Hawaiian culture ranging from double                           
hulled voyaging canoes, called Wa'a kaulua; to small, single hulled outrigger canoes called Wa'a                           
kaukahi. The single hulled outrigger canoe was considered in this study; it can be identified by                               
the attached float (`ama) that adds to the vessel's buoyancy and increases the roll stability, shown                               
in Figure 1. Without doubt, the outrigger technology is a remarkable solution to the problem of                               
roll stability for dugout canoes that can still be observed in modern canoe designs.   
Figure 1: ​Drawing of a Hawaiian style single outrigger canoe that identifies the main                           
components of an outrigger canoe.  
 
1.2 Objectives 
The primary goal of our research was to identify the major differences and modifications                           
between traditional and modern outrigger canoes. To do this, the following objectives needed to                           
be accomplished: 
➢ Identify manufacturing processes, the materials used in the manufacturing of traditional                     
Hawaiian canoe and indigenous knowledge in engineering; 
➢ Identify manufacturing processes and materials used in the manufacturing of modern                     
style outrigger canoe; 
1 
➢ Comparison of traditional Hawaiian canoe and modern style outrigger canoe.  
 
1.3 Overview 
Chapter 2 focuses on the traditional Hawaiian canoe ­­ the materials used, the                         
manufacturing processes and surface treatment. Chapter 3 then continues with a case study of the                             
the materials and manufacturing processes used by a local canoe manufacturer. The results of the                             
case study apply to modern canoe manufacturing in general. Chapter 4 makes a comparison                           
between traditional and modern outrigger canoe manufacturing, followed by an overall                     
conclusion.  
 
2. Traditional Hawaiian Canoe 
2.1 Background   
The outrigger canoe was an essential part of ancient Hawaiian life. The large double                           
hulled canoe (waʻa kaulua) helped polynesians navigate the arduous journey from Tahiti to                         
Hawaii. Upon their arrival, they found an abundance of Koa trees. This discovery led to a new                                 
type of outrigger canoe. 
The design of each canoe matched the purpose it would serve. Canoes were vital for                             
fishing, transportation, war and recreation. The process by which they were made was done by                             
specialists (kahuna kālai waʻa) that would dedicate their lives to the rituals and craftsmanship                           
required to produce seaworthy vessels[2]. 
 
Figure 2:​ ​A small traditional Hawaiian canoe. 
 
 
 
   
2 
2.2 Materials  
The materials used in the manufacturing of traditional Hawaiian canoes can be split into                           
two parts: the material for the hull and the components connected to the hull, and the joining                                 
material which bound them together. For the purposes of this document, the mechanical                         
properties of the hull and adjoining parts connected to the hull are considered, of which all are                                 
usually made of Koa. 
Koa (​Acacia Koa​) is a Hawaiian hardwood and considered Hawaii’s finest native tree. In                           
modern times the supply of Koa is scarce, but in antiquity, Koa was plentiful. The hull of the                                   
traditional Hawaiian canoe was typically made from the trunk a Koa tree. The trunk selected was                               
anywhere from 20 to 60 feet (6 to 18.3 m) in length and between 10 to 12 feet (3 to 3.7 m)in                                           
circumference. Spreaders, called Wae, were made of the same material and were placed inside                           
the hull horizontally (in compression) to prevent the hull from collapsing on itself. Pieces were                             
attached to the bow and stern of the ship to break the waves which were also made of Koa. 
Koa is considered a hardwood and has similar mechanical properties to Black Walnut[3].                         
Acacia Koa behaves as a brittle material and has a variable density, making it difficult to machine or                                   
work by hand[3]​. In woods, the modulus of rupture is used to compare species. The modulus of                                 
rupture is commonly known as the flexural or fracture strength. Woods are tested using a three                               
point flexural test. 
 
Table 1: ​Mechanical properties of Acacia Koa and Black Walnut 
 
Density 
(kg/m​3​
) 
Specific 
Gravity 
Modulus of 
rupture (kPa) 
Modulus of 
elasticity (MPa) 
Compression 
strength parallel 
to grain (kPa) 
Black Walnut[5] 
(Green) 
510*  0.51  66000  9800  29600 
Black Walnut[5] 
(12% moisture 
content) 
550*  0.55  101000  11600  52300 
Koa[4] (green)  529  0.53 
87000  10370  48700 
Koa[4] (12% moist)  545  0.61 
Koa[3] (air dry)  608.7  0.55  ­  ­  ­ 
*Calculated values assuming a density of water of 1000 kg/m​3 
 
Despite its variable density, Koa’s average density is still around half the density of                           
saltwater, which allows it to float. In Table 1 it can be seen that the density of Koa appears to                                       
increase as its moisture content decreases. 
3 
2.3 Manufacturing Processes  
When a suitable Koa tree is selected, it is carefully cut down using ancient adzes called                               
ko`i. The care taken in cutting down the tree is partly due to tradition, but it is also so as to not                                           
damage the trunk as it falls. 
The Adze or Ko`i [6] was an invaluable tool used by canoe builders to not only cut down                                   
the Koa tree, but to shape the canoe as well. There were several types of Ko`i. Refer to Appendix                                     
A ­ Figure 1 for an illustration of several types of Ko`i. Each had its own function and name, but                                       
they all had the same basic components. The Tang, or the cutting blade, was made out of shaped                                   
basaltic stone. The Tang was lashed to a Haft or a handle which was usually made from branches                                   
of Hau (Hibiscus tiliaceus). The Lashing that bound the Tang to the Haft was made from the bark                                   
of the same Hau branches. 
Vertical cuts or scarfs are cut into the base of the tree roughly one meter apart [2]. When                                   
the scarfs are deep enough, the wood between the scarfs is chipped away. The wood chips are cut                                   
with the grain of the wood. This helps prevent the wood from cracking vertically along the trunk.  
Before the tree falls, a bed of fern, the Hapu`u (Cibotium Menziesii), is laid out on the                                 
forest floor to cushion the fall. With the tree safely on the ground, the branches and the bark at                                     
the top of the tree is ceremoniously removed to preserve the spirit of the wood. Then the rest of                                     
the branches and the bark are removed. Now the hewing can begin. 
The Hewing is a rough shaping of the canoe. The bow, the stern, and the sides are cut out,                                     
and the beginnings of the interior also starts to take shape in this process. With the Ko`i, the                                   
wood is chipped away piece by piece. In this process, a large section of the bow is left uncut on                                       
the canoe. This neck is used to make transportation, usually downhill, possible. This is essential                             
as the unfinished canoe often would weigh several hundred pounds. Rope is tied to the neck and                                 
a team of people supports the weight of the canoe as it slides down the hill. When the canoe                                     
makes it to the village down at the beach, it is housed in a shelter and allowed to cure for days,                                         
weeks, or even years, depending on the size of the canoe.  
Other tools used to shape and finish the canoe were Stone Chisels called Pōhaku Pao.                             
These chisels were used to punch holes into the hull of the canoe for Hau branch lashing and                                   
other components to pass through. When these holes were punched through with the chisels,                           
seashells called Pūpū were used to smooth out the holes. For smaller holes in thinner parts of the                                   
canoe, a pump drill called Nao Wili was used. The Nao Wili is shown in Appendix A ­ Figure 2. 
After the wood has been given the chance to cure, it is now ready for final shaping. The neck is                                       
cut from the bow of the canoe, and the bottom is rounded off and smoothen out using stones                                   
called Pōhaku `Ānai. The final shaping of the interior is also done.  
Next comes the installation of the outrigger or the ‘Ama [7]. The ‘ama was usually a                               
smoothed out narrow long piece of Koa that was lashed to the main hull by two shafts called                                   
`iako. The `ama was smoothed out by the Pōhaku `Ānai and affixed to the left side of the hull                                     
(being that was usually the leeward side of the canoe). Now the canoe is ready for surface                                 
treatment and further curing. 
4 
2.4 Surface Treatment   
After the polishing was done by the moʻo, it was time for waterproofing and painting.                             
Kukui nut oil was often used to waterproof the hull. However, the paint was usually the most                                 
effective treatment to seal the surface. A black paint (pā`ele) was made by first crushing buds                               
from the `akoko shrub, flowers from the banana plant (mai`a), and the inner bark from kukui tree                                 
roots into a liquid. A charcoal powder from burnt wiliwili wood or lau hala leaves was added to                                   
the liquid, then strained through a mesh of `ahu`awa sedge. Finally, juice from ti plant root was                                 
added to the mixture to make the paint colorfast. This paint would be applied by coconut husk,                                 
hala root, or even bare hands[2]. 
3. Case Study of Modern Canoe Manufacturing 
3.1 Background  
With increasing popularity in outrigger canoe racing, modern outrigger canoe                   
manufactures aim to design fast, light­weight, and versatile boats. MAXSURF, a marine vessel                         
design and analysis software, SOLIDWORKS, and other computer software programs are used                       
in the design process of modern canoes. These software programs provide the designer with tools                             
for structural and strength analysis, stability analysis, and computational fluid dynamics.  
Kamanu Composites is a local canoe manufacturer that builds superior and                     
high­performance canoes. Kamanu Composites builds all of their canoes in­house from                     
beginning to end while striving for "perfection within every step of the manufacturing                         
process''[8]. A case study of materials and manufacturing used in the building of their canoes                             
was performed; the results of the case study are as follows.  
 
3.2 Materials   
3.2.1 Carbon Fiber 
The manufacturer uses AS4 which is a 12x12, 3000 strand, Standard Modulus carbon                         
fiber weave with an epoxy resin to create a Carbon Fiber Reinforced Polymer in the build.                               
Carbon Fiber typically has much higher strength in one direction than the other. AS4 is a weave                                 
of carbon fibers which can result in high strength in multiple directions. 
Carbon fiber can be compared to fiberglass with respect to its flexibility and ease of use,                               
but has the highest specific stiffness of any commercially available fiber and is considerably                           
lighter than fiberglass. Carbon Fiber Reinforced Polymers have a high strength in tension and                           
compression, and a high resistance to corrosion, creep, and fatigue. There are High and Ultra                             
High Modulus Carbon Fibers available but the additional cost and high brittle characteristics of                           
those materials make AS4 the clear choice for this particular manufacturer’s build.  
The AS4 is both more flexible and affordable than other options and provides more than                             
enough strength and rigidity for their needs. The results in the table shown in Appendix A ­                                 
Table 1 were obtained from data which a popular carbon fiber manufacturer has provided[9]. 
5 
3.2.2 S­glass® 
S­glass is the trade name for a stronger version of standard fiberglass cloth (E­glass)                           
which was invented by Owens Corning Co. in the late 1990’s[10]. This is a type of cloth                                 
consisting of fine filaments of glass that are combined in yarn and embedded in resin to make a                                   
high strength structure. The canoe builder uses one of the lighter forms of this particular                             
fiberglass which weighs in at roughly 2.5 grams per cubic centimeter. The flexibility of the                             
pre­impregnated cloth is greater than that of the carbon fiber. The numbers in the table in                               
Appendix A ­ Table 2 come directly from the Owens Corning website.  
3.2.3 Divinycell® 
One of the key components in all ship building is buoyancy. Kamanu Composites                         
maximizes this in their builds by sandwiching a semi­rigid PVC foam between the laminate                           
fibers called Divinycell H80[11]. This particular semi­rigid foam has a high strength to weight                           
ratio, good properties for tensile and compressive strength, and is extremely light. Divinycell is                           
widespread in the marine, transportation, and aerospace industries, and can be used in countless                           
applications where strength, stiffness, and low weight are desired. The numbers in Appendix A ­                             
Table 3 come directly from the manufacturer of Divinycell.  
3.2.4 Coremat® (2mm) 
Coremat is a flexible nonwoven material used where the bends as designed by the ship                             
builder have too small of a radius for the used of Divinycell. The use of the Coremat extends                                   
similar weight and resin saving properties of Divinycell while maintaining stiffness and rapid                         
thickness build up of the core foam in the hand lay­up process. The numbers in in Appendix A ­                                     
Table 4 come directly from the manufacturer of Coremat[12].  
3.2.4 Epoxy Resin 
In a sandwich construction process all the components are important but perhaps none                         
more so than the choice of the resin. The resin is the literal glue that binds the layers of laminate                                       
and core foam together. Kamanu Composites uses a Proset Laminating Epoxy[13] in their builds.                           
No specific data sheet for their product could be found so the numbers from a competitor ­                                 
Westsystem[14] were used in Appendix A ­ Table 5.  
 
3.3 Manufacturing Processes  
A variety of manufacturing processes can be observed at Kamanu Composites as the                         
entire canoe is manufactured in­house from beginning to end (except for the `iako ). While                           1
Kamanu fabricates their own molds, rudders, seats, and fins, this paper focusses on the processes                             
involved in the fabrication of the boat and the `ama. Both the boat and the `ama are fabricated in                                     
1
 Because the `iako is composed of 6061 Aluminum that needs to be anodized, in­house fabrication is unfeasible. 
6 
two parts ­­ the hull and the deck ­­ which are then joined with a ½ in lap joint. The fabrication                                         
time of a canoe at Kamanu Composites is 60 man hours, and the goal is to complete one boat per                                       
day.  
3.3.1 Vacuum Bagging Process  
The process starts by wiping down the mold with a wax based mold release formula. For                               
each boat design there are two deck and two hull molds, shown in Figure 3. Each part takes two                                     
days in the mold which allows the team to complete one boat per day. The next step is to apply a                                         
gel coat which protects the surface and the construction underneath while allowing a customer a                             
choice in color and design. The boat is then allowed to rest overnight and is checked the                                 
following morning for defects. 
 
Figure 3​:​ Custom molds used for the deck and hull in the vacuum bagging process. 
The layup follows the concept of sandwich construction, where either the divinycell or                         
coremat is sandwiched between layers of carbon fiber or s­glass. The layup ­­ the combination of                               
materials and type of materials ­­ can be varied to adjust strength, weight, and flexibility                             
according to customer demands, which is illustrated by the following example.  
The standard layup for the deck of the Pueo model consists of a 3.9 oz (110.6 g) carbon                                   
layer, a ⅛ in (3.1 mm) foam core, and a 4.8 oz (136.0 g) carbon layer on the inside. The layup of                                           
the hull, on the other hand, is composed of two layers of 4.0 S glass on the outside, a ⅛ in (3.1                                           
mm) foam core, and a 4.8 oz (136.0 g) carbon layer on the inside, resulting in a total weight of                                       
23 lbs (10.4 kg). In comparison, when manufactured with layers of 3.9 oz carbon on the interior                                 
of hull and deck, the weight is reduced to 22 lbs (9.9 kg); yet, the impact resistance and overall                                     
strength remain the same.  
7 
If no repairs are needed after the gel coat process has been completed, the various layers                               
of fabric and foam are carefully laid out in a sandwich design and the epoxy is applied. After the                                     
epoxy resin has been applied, a large plastic bag is fashioned and is then placed over the canoe                                   
and vacuum is applied. Vacuum bagging is a technique used to put pressure on a laminate during                                 
curing. Applying pressure to the laminate increases its strength by removing air trapped between                           
layers and compacting the fibers of the laminate to ensure they resist shifting during the curing                               
cycle. The vacuum also pulls out any trapped moisture in the air, circulates the resin through to                                 
saturate each piece of laminate to the core material, and most importantly, optimizes the                           
fiber­to­resin ratio. 
The canoe is then placed in an autoclave for a minimum of five hours. Neither the s­glass                                   
nor the carbon fiber have any particularly impressive strength when in their non­laminated state.                           
The laminates are simple cloth before impregnation and the resin is extremely brittle if cured                             
without reinforcement from the cloth. Any excess resin or dry laminate lowers the overall                           
strength of the boat. It is the combination of these materials that makes the composite exhibit                               
such impressive strength to weight properties. This creates a lightweight yet incredibly strong                         
finished panel.  
3.3.2 CNC Machining 
CNC machining plays a major role in the cutting of the foam (divinycell and coremat).                             
Accurate foam cut­outs are crucial in the fabrication of superior boats. Kamanu Composites uses                           
industrial CNC machines to ensure accuracy and quality of the foam parts. Appendix A ­ Figure                               
3 shows the CNC machine used.  
3.3.3 Finish and Quality Control 
After the hull, the deck and the `ama have cured in the autoclave, they are joined together                                 
using epoxy adhesives. To finish the assembly of the canoe, `iako mounts and seats are installed.                               
If the design has a rudder, foot pedals are also integrated.  
Quality control is integrated into the manufacturing along each step in the manufacturing                         
process; each part is analyzed for defects and fixed if necessary as quality is most important for                                 
Kamanu Composites. Finally, a surface finish is applied. 
 
3.4 Surface Treatment  
As described in Chapter 3.3.1, the surface of the boat is a gel coat that serves as a                                   
protective finish to the hull. The main purpose is to prevent damage from abrasions and the                               
penetration of moisture. It is a polyester resin with a higher viscosity and hardness than a                               
standard resin. This allows for both easy application and increases the structural integrity of the                             
fiberglass material. These properties are due to the use of Isophthalic/Neopentyl Glycol                       
(ISO/NPG) resin. 
8 
The Coating is applied by a relatively simple process. First the surface is prepared by                             
sanding any imperfections smooth, then cleaning any debris, oil, or paint that may inhibit                           
adhesion. Next, the gelcoat, catalyst and tinting are mixed together and are now ready for                             
application. This can be done either with a sprayer or roller. It is important to sand between                                 
layers as this allows for proper adhesion. The curing process takes between four and six hours                               
before a final hardness is ready[15].   
4. Comparison   
To make a comparison between ancient traditional Hawaiian canoes and modern canoes,                       
several factors must be taken into account and looked at both objectively and subjectively. On                             
the surface, it is easy to say that modern canoes are far superior to ancient canoes, for that is                                     
indeed the goal of the evolution of manufacturing ­­ to improve upon a product. However, from                               
an objective point of view, the factors that will be discussed and compared are materials,                             
manufacturing methods, production time, performance, and expected canoe life. From a                     
subjective point of view, artistic quality, value and use will be discussed.  
The evolution of the materials used to construct racing canoes has resulted in lighter,                           
stronger, and faster canoes. The weight­to­strength ratios are much higher with modern canoes.                         
This is not to say that the ancient Hawaiian canoes were not strong, but they were much heavier.                                   
With modern methods of manufacturing, not only has the time to construct a canoe been                             
drastically reduced, but the product consistency has increased. Ancient canoes varied from one                         
another due to factors such as tree size, location of knots, and wood grain. Although the methods                                 
were similar, every craftsman made them a little different, to the point where each canoe was a                                 
unique creation. 
The performance of modern canoes not only improved, but using modern computer                       
design programs such as SOLIDWORKS, the performance changes and hydrodynamic                   
properties can be predicted by using mathematical formulas, and studied without a                       
“trial­and­error” approach that would have been otherwise needed to test each canoe                       
manufactured. Since a new canoe is not needed each time to test performance, there is less waste                                 
of material and time.  
These factors however, do not necessarily mean modern canoes are superior to ancient                         
canoes. Modern canoes for example, have an average life of approximately ten years due to a                               
phenomenon called blistering which delaminates the material. This is caused by water getting                         
under the gel coating. The life of the canoe can be extended with proper care, such as fresh­water                                   
rinses when not in use, complete drying, and minimizing exposure to direct sunlight. However,                           
traditional canoes (made of wood) can in many instances last much longer.  
From a subjective standpoint, the reasons for using canoes have evolved just as the                           
manufacturing has, and it would not be fair to say that modern canoes are superior. Ancient                               
Hawaiian canoes had much more uses than modern canoes and were valued by the Hawaiians.                             
They were unique pieces of art as well, and  symbols of the communities that built them. 
9 
5. Conclusion  
The focus of this research was an analysis of the materials and manufacturing process                           
involved in the building of traditional Hawaiian and modern single hulled outrigger canoes with                           
the ultimate goal to compare similarities and differences. By applying modern theory on the                           
manufacturing processes to such a specific and local product with tremendous cultural history,                         
we were able to identify some of the indigenous knowledge of ancient Hawaiian culture, as well                               
as some of the modern advancements in composite manufacturing.  
In summary, our research showed that traditional canoes were carved out of Koa wood,                           
then cured, and their surface treated with natural oils and paint to improve the material                             
properties, mitigate fatigue life, and ensure longevity of the canoe. Modern manufactures on the                           
other hand strive to design and build lighter, stronger, and faster canoes by optimizing their                             
designs through simulation software (computer software), composite materials, and composites                   
manufacturing techniques such as vacuum bagging.  
An objective and subjective comparison showed that there are parallels in the                       
manufacturing processes and that modern canoes are still modelled after ancient designs. While                         
mechanical properties and the manufacturing processes are far superior to traditional ones in                         
terms of weight, strength, and production time, the cultural value, uniqueness, and the ancient                           
engineering knowledge embedded in a traditional Hawaiian outrigger canoe are remarkable.  
 
 
   
10 
Appendix A 
A.1 Tables  
 
Table 2:​ ​CFRP Material Properties based on a weight ratio of 60% carbon fiber to 40% epoxy resin​[9]. 
Carbon Fiber Reinforced Polymer 
(CFRP) 
Test Results  Comments 
Density (kg/m³)  1.79g/cm3   
Tensile Modulus  245 GPa  ASTM D3039 
Tensile Strength, Ultimate  4620 MPa  ASTM D3039 
Elongation at Failure  1.8%   
 
 
Table 3:​ ​S­glass Properties​[9]. 
Owens Corning S­glass  Test Results  Comments 
Density  2.49 g/cm​3 
 
Tensile Modulus  88 GPa  ISO 527­5 
Tensile Strength  1550 MPa  ISO 527­5 
Poissons Ratio  0.27  ASTM D638 ­ 0.27 
 
 
Table 4: ​Divinycell Material Properties​[11]. 
Divinycell H80  Test Results  Comments 
Tensile Strength, Ultimate  2.20 MPa  ASTM D1623 
Elongation at Break  18%  Shear Strain 
Tensile Modulus  0.0800 GPa   
Compressive Strength  1.20  ASTM D1621 
Compressive Modulus  0.085 MPa  ASTM D1621­B 
Poissons Ratio  0.032   
Shear Modulus  0.03099 GPa  ASTM C273 
Shear Strength  0.951 MPa  Yield; ASTM C273­00   
 
 
 
 
11 
 
Table 5:​ ​Coremat Material Properties​[12]. 
Coremat (2mm)  Test Results  Comments 
Dry Weight  96 g/m2   
Density Impregnated  540 kg/m3   
Flexural strength  8.5 MPa  ASTM D790 
Flexural Modulus  1250 MPa  ASTM D790 
Compressive Strength (10% strain)  10 MPa  ISO 844 
Shear Strength  3 MPa  ASTM C273­61 
Shear Modulus  25 MPa  ASTM C273­61 
 
 
Table 6:​ ​Physical Properties of Cured Epoxy​[13]. 
Cured Epoxy  Test Results  Comments 
Hardness (Shore D)  83  ASTM D­2240 
Compression yield  1155 MPa  ASTM D­695 
Tensile strength  800 MPa  ASTM D­695 
Tensile elongation  3.4%  ASTM D­695 
Tensile modulus  41340 MPa  ASTM D­695 
Flexural strength  1428 MPa  ASTM D­790 
Flexural modulus  46710 MPa  ASTM D­790 
 
 
 
   
12 
A.2 Figures  
 
Figure 4:​ ​Illustration of Ko`i, Hawaiian Adze 
 
 
Figure 5: ​Illustration of Nao Wili pump drill 
 
 
13 
 
Figure 5:​ ​Picture of CNC Machine at Kamanu Composites 
 
 
More figures to come for modern canoe 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
14 
 
Acknowledgements 
We would like to thank Kamanu Composites Inc. for offering their support and letting us visit                               
their company to observe and learn about their manufacturing process at first hand. We would                             
especially like to say Mahalo to Keizo Gates, who went out of his way in showing us around and                                     
responding to follow up questions.  
 
 
Bibliography 
 
[1] Thompson,Nainoa. (undated) `Ike: Knowledge and Traditions Retrieved: April 23, 2015, from  
        ​http://pvs.kcc.hawaii.edu/ike/intro_ike.html​. 
 
[2] Chun, Naomi NY, Hawaiian Canoe­Building Traditions, Revised Edition, Kamehameha Schools  
        Press. Honolulu, 1995, pp. 3­39 
 
[3] Skolmen, Roger G. (2000). Some Woods of Hawaii. Retrieved from University of Hawaii, College  
        of Tropical Agriculture and Human Resources. Retrieved: May 1, 2015, from   
        ​http://www.ctahr.hawaii.edu/oc/freepubs/pdf/RM­7.pdf 
 
[4] Smithsonian Museum Conservation Institute. (undated). Microscopy: Technical Information Sheet:  
        ACACIA KOA. Retrieved: May 4, 2015, from  
http://www.si.edu/mci/english/professional_development/past_courses_programs/programs/acacia_koa.ht
ml 
 
[5] Green, David W., Winandy, Jerrold E., & Kretschmann, David E. (undated). Mechanical Properties  
        of Wood. Retrieved: May 2, 2015, from 
        h​ttp://www.conradfp.com/pdf/ch4­Mechanical­Properties­of­Wood.pdf 
 
[6] Polynesian Voyaging Society, “Plants and Tools Used for Building Canoes”, Retrieved: May  
        4, 2015, from ​http://pvs.kcc.hawaii.edu/ike/kalai_waa/plants_and_tools.html  
 
[7] The Encyclopedia of New Zealand, “Story Waka Ama ­ Outrigger Canoe”, Retrieved: May 6,  
        2015, from ​http://www.teara.govt.nz/en/waka­ama­outrigger­canoeing  
 
[8] Kamanu Composites. “Reason for being” (2014). Retrieved: Apr. 26, 2015,  
        http://www.kamanucomposites.com/company 
 
[9]"Hexcel.com ­ HexTow® Continuous Carbon Fiber Products." 2011. Retrieved: Apr. 27,  
15 
        2015, from ​http://www.hexcel.com/Resources/Cont­Carbon­Fiber­Data­Sheets 
 
[10] “Owens Corning Composite Materials." 2011. Retrieved: May. 3, 2015, from   
        ​http://composites.owenscorning.com/ 
 
[11] “Core Material ­ Diab." 2012. Retrieved:  May. 3, 2015, from  
        ​http://www.diabgroup.com/Products­and­services/Core­Material 
 
[12] “Coremat® : TAP Plastics.” 2012. Retrieved:  May. 3, 2015, from  
        ​http://www.tapplastics.com/product/fiberglass/carbon_specialty_fabrics/coremat/93 
 
[13] "Proset Laminating Epoxies ­ PRO­SET Epoxies." 2005. Retrieved: 2 May. 2015, from   
        ​http://prosetepoxy.com/laminating_epoxies.html 
 
[14] "Physical Properties ­ WEST SYSTEM Epoxy." 2008. Retrieved: May. 3, 2015, from   
         ​http://www.westsystem.com/ss/typical­physical­properties/ 
 
[15]  "GEL COAT: Basic Information ­ Evercoat." 2011. Retrieved: May. 1, 2015, from  
         ​http://www.evercoat.com/imgs/pis/gelcoat.pdf 
 
 
 
 
 
16 

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Traditional vs Modern Canoe Manufacturing

  • 1.               Comparison of Traditional Hawaiian and Modern Outrigger Canoe Manufacturing   ­     Dept. of Mechanical Engineering    University of Hawai'i at Mānoa          Students:  Justin Dery     Advisor:   Dr. Jingjing Li, Ph. D.    Jeffrey Ibara      Mitch McLean   William Segall        Holm Smidt        Joseph Valle              Abstract:   In this report, we will compare ancient Hawaiian canoe building to the modern                          production of canoes. Comparing the materials used, the methods of construction, and the tools                            at each builder’s disposal. It would be obvious to say that things have gotten better over time, but                                    there are methods and components from ancient traditions that are still very much a part of how                                  canoes are built today.            
  • 2. 1. Introduction   As engineering students in Hawaii, it is hard not to notice the engineering solutions                            produced by ancient Hawaiians. In a remarkable feat of achievement not seen elsewhere until                            several hundred to thousands of years later, the ancient Hawaiians engineered, built, and                          navigated vessels capable of traversing the vast expanse of the Pacific Ocean without the benefit                              of metals[1].  In this paper, we aim to investigate the materials and manufacturing processes of the                            ancient Hawaiian people, as well as detailing what improvements and advancements have been                          made to canoe design, and how the modern design evolved from its traditional Hawaiian roots.     1.1 The Outrigger Canoe   A variety of canoe designs can be observed from Hawaiian culture ranging from double                            hulled voyaging canoes, called Wa'a kaulua; to small, single hulled outrigger canoes called Wa'a                            kaukahi. The single hulled outrigger canoe was considered in this study; it can be identified by                                the attached float (`ama) that adds to the vessel's buoyancy and increases the roll stability, shown                                in Figure 1. Without doubt, the outrigger technology is a remarkable solution to the problem of                                roll stability for dugout canoes that can still be observed in modern canoe designs.    Figure 1: ​Drawing of a Hawaiian style single outrigger canoe that identifies the main                            components of an outrigger canoe.     1.2 Objectives  The primary goal of our research was to identify the major differences and modifications                            between traditional and modern outrigger canoes. To do this, the following objectives needed to                            be accomplished:  ➢ Identify manufacturing processes, the materials used in the manufacturing of traditional                      Hawaiian canoe and indigenous knowledge in engineering;  ➢ Identify manufacturing processes and materials used in the manufacturing of modern                      style outrigger canoe;  1 
  • 3. ➢ Comparison of traditional Hawaiian canoe and modern style outrigger canoe.     1.3 Overview  Chapter 2 focuses on the traditional Hawaiian canoe ­­ the materials used, the                          manufacturing processes and surface treatment. Chapter 3 then continues with a case study of the                              the materials and manufacturing processes used by a local canoe manufacturer. The results of the                              case study apply to modern canoe manufacturing in general. Chapter 4 makes a comparison                            between traditional and modern outrigger canoe manufacturing, followed by an overall                      conclusion.     2. Traditional Hawaiian Canoe  2.1 Background    The outrigger canoe was an essential part of ancient Hawaiian life. The large double                            hulled canoe (waʻa kaulua) helped polynesians navigate the arduous journey from Tahiti to                          Hawaii. Upon their arrival, they found an abundance of Koa trees. This discovery led to a new                                  type of outrigger canoe.  The design of each canoe matched the purpose it would serve. Canoes were vital for                              fishing, transportation, war and recreation. The process by which they were made was done by                              specialists (kahuna kālai waʻa) that would dedicate their lives to the rituals and craftsmanship                            required to produce seaworthy vessels[2].    Figure 2:​ ​A small traditional Hawaiian canoe.            2 
  • 4. 2.2 Materials   The materials used in the manufacturing of traditional Hawaiian canoes can be split into                            two parts: the material for the hull and the components connected to the hull, and the joining                                  material which bound them together. For the purposes of this document, the mechanical                          properties of the hull and adjoining parts connected to the hull are considered, of which all are                                  usually made of Koa.  Koa (​Acacia Koa​) is a Hawaiian hardwood and considered Hawaii’s finest native tree. In                            modern times the supply of Koa is scarce, but in antiquity, Koa was plentiful. The hull of the                                    traditional Hawaiian canoe was typically made from the trunk a Koa tree. The trunk selected was                                anywhere from 20 to 60 feet (6 to 18.3 m) in length and between 10 to 12 feet (3 to 3.7 m)in                                            circumference. Spreaders, called Wae, were made of the same material and were placed inside                            the hull horizontally (in compression) to prevent the hull from collapsing on itself. Pieces were                              attached to the bow and stern of the ship to break the waves which were also made of Koa.  Koa is considered a hardwood and has similar mechanical properties to Black Walnut[3].                          Acacia Koa behaves as a brittle material and has a variable density, making it difficult to machine or                                    work by hand[3]​. In woods, the modulus of rupture is used to compare species. The modulus of                                  rupture is commonly known as the flexural or fracture strength. Woods are tested using a three                                point flexural test.    Table 1: ​Mechanical properties of Acacia Koa and Black Walnut    Density  (kg/m​3​ )  Specific  Gravity  Modulus of  rupture (kPa)  Modulus of  elasticity (MPa)  Compression  strength parallel  to grain (kPa)  Black Walnut[5]  (Green)  510*  0.51  66000  9800  29600  Black Walnut[5]  (12% moisture  content)  550*  0.55  101000  11600  52300  Koa[4] (green)  529  0.53  87000  10370  48700  Koa[4] (12% moist)  545  0.61  Koa[3] (air dry)  608.7  0.55  ­  ­  ­  *Calculated values assuming a density of water of 1000 kg/m​3    Despite its variable density, Koa’s average density is still around half the density of                            saltwater, which allows it to float. In Table 1 it can be seen that the density of Koa appears to                                        increase as its moisture content decreases.  3 
  • 5. 2.3 Manufacturing Processes   When a suitable Koa tree is selected, it is carefully cut down using ancient adzes called                                ko`i. The care taken in cutting down the tree is partly due to tradition, but it is also so as to not                                            damage the trunk as it falls.  The Adze or Ko`i [6] was an invaluable tool used by canoe builders to not only cut down                                    the Koa tree, but to shape the canoe as well. There were several types of Ko`i. Refer to Appendix                                      A ­ Figure 1 for an illustration of several types of Ko`i. Each had its own function and name, but                                        they all had the same basic components. The Tang, or the cutting blade, was made out of shaped                                    basaltic stone. The Tang was lashed to a Haft or a handle which was usually made from branches                                    of Hau (Hibiscus tiliaceus). The Lashing that bound the Tang to the Haft was made from the bark                                    of the same Hau branches.  Vertical cuts or scarfs are cut into the base of the tree roughly one meter apart [2]. When                                    the scarfs are deep enough, the wood between the scarfs is chipped away. The wood chips are cut                                    with the grain of the wood. This helps prevent the wood from cracking vertically along the trunk.   Before the tree falls, a bed of fern, the Hapu`u (Cibotium Menziesii), is laid out on the                                  forest floor to cushion the fall. With the tree safely on the ground, the branches and the bark at                                      the top of the tree is ceremoniously removed to preserve the spirit of the wood. Then the rest of                                      the branches and the bark are removed. Now the hewing can begin.  The Hewing is a rough shaping of the canoe. The bow, the stern, and the sides are cut out,                                      and the beginnings of the interior also starts to take shape in this process. With the Ko`i, the                                    wood is chipped away piece by piece. In this process, a large section of the bow is left uncut on                                        the canoe. This neck is used to make transportation, usually downhill, possible. This is essential                              as the unfinished canoe often would weigh several hundred pounds. Rope is tied to the neck and                                  a team of people supports the weight of the canoe as it slides down the hill. When the canoe                                      makes it to the village down at the beach, it is housed in a shelter and allowed to cure for days,                                          weeks, or even years, depending on the size of the canoe.   Other tools used to shape and finish the canoe were Stone Chisels called Pōhaku Pao.                              These chisels were used to punch holes into the hull of the canoe for Hau branch lashing and                                    other components to pass through. When these holes were punched through with the chisels,                            seashells called Pūpū were used to smooth out the holes. For smaller holes in thinner parts of the                                    canoe, a pump drill called Nao Wili was used. The Nao Wili is shown in Appendix A ­ Figure 2.  After the wood has been given the chance to cure, it is now ready for final shaping. The neck is                                        cut from the bow of the canoe, and the bottom is rounded off and smoothen out using stones                                    called Pōhaku `Ānai. The final shaping of the interior is also done.   Next comes the installation of the outrigger or the ‘Ama [7]. The ‘ama was usually a                                smoothed out narrow long piece of Koa that was lashed to the main hull by two shafts called                                    `iako. The `ama was smoothed out by the Pōhaku `Ānai and affixed to the left side of the hull                                      (being that was usually the leeward side of the canoe). Now the canoe is ready for surface                                  treatment and further curing.  4 
  • 6. 2.4 Surface Treatment    After the polishing was done by the moʻo, it was time for waterproofing and painting.                              Kukui nut oil was often used to waterproof the hull. However, the paint was usually the most                                  effective treatment to seal the surface. A black paint (pā`ele) was made by first crushing buds                                from the `akoko shrub, flowers from the banana plant (mai`a), and the inner bark from kukui tree                                  roots into a liquid. A charcoal powder from burnt wiliwili wood or lau hala leaves was added to                                    the liquid, then strained through a mesh of `ahu`awa sedge. Finally, juice from ti plant root was                                  added to the mixture to make the paint colorfast. This paint would be applied by coconut husk,                                  hala root, or even bare hands[2].  3. Case Study of Modern Canoe Manufacturing  3.1 Background   With increasing popularity in outrigger canoe racing, modern outrigger canoe                    manufactures aim to design fast, light­weight, and versatile boats. MAXSURF, a marine vessel                          design and analysis software, SOLIDWORKS, and other computer software programs are used                        in the design process of modern canoes. These software programs provide the designer with tools                              for structural and strength analysis, stability analysis, and computational fluid dynamics.   Kamanu Composites is a local canoe manufacturer that builds superior and                      high­performance canoes. Kamanu Composites builds all of their canoes in­house from                      beginning to end while striving for "perfection within every step of the manufacturing                          process''[8]. A case study of materials and manufacturing used in the building of their canoes                              was performed; the results of the case study are as follows.     3.2 Materials    3.2.1 Carbon Fiber  The manufacturer uses AS4 which is a 12x12, 3000 strand, Standard Modulus carbon                          fiber weave with an epoxy resin to create a Carbon Fiber Reinforced Polymer in the build.                                Carbon Fiber typically has much higher strength in one direction than the other. AS4 is a weave                                  of carbon fibers which can result in high strength in multiple directions.  Carbon fiber can be compared to fiberglass with respect to its flexibility and ease of use,                                but has the highest specific stiffness of any commercially available fiber and is considerably                            lighter than fiberglass. Carbon Fiber Reinforced Polymers have a high strength in tension and                            compression, and a high resistance to corrosion, creep, and fatigue. There are High and Ultra                              High Modulus Carbon Fibers available but the additional cost and high brittle characteristics of                            those materials make AS4 the clear choice for this particular manufacturer’s build.   The AS4 is both more flexible and affordable than other options and provides more than                              enough strength and rigidity for their needs. The results in the table shown in Appendix A ­                                  Table 1 were obtained from data which a popular carbon fiber manufacturer has provided[9].  5 
  • 7. 3.2.2 S­glass®  S­glass is the trade name for a stronger version of standard fiberglass cloth (E­glass)                            which was invented by Owens Corning Co. in the late 1990’s[10]. This is a type of cloth                                  consisting of fine filaments of glass that are combined in yarn and embedded in resin to make a                                    high strength structure. The canoe builder uses one of the lighter forms of this particular                              fiberglass which weighs in at roughly 2.5 grams per cubic centimeter. The flexibility of the                              pre­impregnated cloth is greater than that of the carbon fiber. The numbers in the table in                                Appendix A ­ Table 2 come directly from the Owens Corning website.   3.2.3 Divinycell®  One of the key components in all ship building is buoyancy. Kamanu Composites                          maximizes this in their builds by sandwiching a semi­rigid PVC foam between the laminate                            fibers called Divinycell H80[11]. This particular semi­rigid foam has a high strength to weight                            ratio, good properties for tensile and compressive strength, and is extremely light. Divinycell is                            widespread in the marine, transportation, and aerospace industries, and can be used in countless                            applications where strength, stiffness, and low weight are desired. The numbers in Appendix A ­                              Table 3 come directly from the manufacturer of Divinycell.   3.2.4 Coremat® (2mm)  Coremat is a flexible nonwoven material used where the bends as designed by the ship                              builder have too small of a radius for the used of Divinycell. The use of the Coremat extends                                    similar weight and resin saving properties of Divinycell while maintaining stiffness and rapid                          thickness build up of the core foam in the hand lay­up process. The numbers in in Appendix A ­                                      Table 4 come directly from the manufacturer of Coremat[12].   3.2.4 Epoxy Resin  In a sandwich construction process all the components are important but perhaps none                          more so than the choice of the resin. The resin is the literal glue that binds the layers of laminate                                        and core foam together. Kamanu Composites uses a Proset Laminating Epoxy[13] in their builds.                            No specific data sheet for their product could be found so the numbers from a competitor ­                                  Westsystem[14] were used in Appendix A ­ Table 5.     3.3 Manufacturing Processes   A variety of manufacturing processes can be observed at Kamanu Composites as the                          entire canoe is manufactured in­house from beginning to end (except for the `iako ). While                           1 Kamanu fabricates their own molds, rudders, seats, and fins, this paper focusses on the processes                              involved in the fabrication of the boat and the `ama. Both the boat and the `ama are fabricated in                                      1  Because the `iako is composed of 6061 Aluminum that needs to be anodized, in­house fabrication is unfeasible.  6 
  • 8. two parts ­­ the hull and the deck ­­ which are then joined with a ½ in lap joint. The fabrication                                          time of a canoe at Kamanu Composites is 60 man hours, and the goal is to complete one boat per                                        day.   3.3.1 Vacuum Bagging Process   The process starts by wiping down the mold with a wax based mold release formula. For                                each boat design there are two deck and two hull molds, shown in Figure 3. Each part takes two                                      days in the mold which allows the team to complete one boat per day. The next step is to apply a                                          gel coat which protects the surface and the construction underneath while allowing a customer a                              choice in color and design. The boat is then allowed to rest overnight and is checked the                                  following morning for defects.    Figure 3​:​ Custom molds used for the deck and hull in the vacuum bagging process.  The layup follows the concept of sandwich construction, where either the divinycell or                          coremat is sandwiched between layers of carbon fiber or s­glass. The layup ­­ the combination of                                materials and type of materials ­­ can be varied to adjust strength, weight, and flexibility                              according to customer demands, which is illustrated by the following example.   The standard layup for the deck of the Pueo model consists of a 3.9 oz (110.6 g) carbon                                    layer, a ⅛ in (3.1 mm) foam core, and a 4.8 oz (136.0 g) carbon layer on the inside. The layup of                                            the hull, on the other hand, is composed of two layers of 4.0 S glass on the outside, a ⅛ in (3.1                                            mm) foam core, and a 4.8 oz (136.0 g) carbon layer on the inside, resulting in a total weight of                                        23 lbs (10.4 kg). In comparison, when manufactured with layers of 3.9 oz carbon on the interior                                  of hull and deck, the weight is reduced to 22 lbs (9.9 kg); yet, the impact resistance and overall                                      strength remain the same.   7 
  • 9. If no repairs are needed after the gel coat process has been completed, the various layers                                of fabric and foam are carefully laid out in a sandwich design and the epoxy is applied. After the                                      epoxy resin has been applied, a large plastic bag is fashioned and is then placed over the canoe                                    and vacuum is applied. Vacuum bagging is a technique used to put pressure on a laminate during                                  curing. Applying pressure to the laminate increases its strength by removing air trapped between                            layers and compacting the fibers of the laminate to ensure they resist shifting during the curing                                cycle. The vacuum also pulls out any trapped moisture in the air, circulates the resin through to                                  saturate each piece of laminate to the core material, and most importantly, optimizes the                            fiber­to­resin ratio.  The canoe is then placed in an autoclave for a minimum of five hours. Neither the s­glass                                    nor the carbon fiber have any particularly impressive strength when in their non­laminated state.                            The laminates are simple cloth before impregnation and the resin is extremely brittle if cured                              without reinforcement from the cloth. Any excess resin or dry laminate lowers the overall                            strength of the boat. It is the combination of these materials that makes the composite exhibit                                such impressive strength to weight properties. This creates a lightweight yet incredibly strong                          finished panel.   3.3.2 CNC Machining  CNC machining plays a major role in the cutting of the foam (divinycell and coremat).                              Accurate foam cut­outs are crucial in the fabrication of superior boats. Kamanu Composites uses                            industrial CNC machines to ensure accuracy and quality of the foam parts. Appendix A ­ Figure                                3 shows the CNC machine used.   3.3.3 Finish and Quality Control  After the hull, the deck and the `ama have cured in the autoclave, they are joined together                                  using epoxy adhesives. To finish the assembly of the canoe, `iako mounts and seats are installed.                                If the design has a rudder, foot pedals are also integrated.   Quality control is integrated into the manufacturing along each step in the manufacturing                          process; each part is analyzed for defects and fixed if necessary as quality is most important for                                  Kamanu Composites. Finally, a surface finish is applied.    3.4 Surface Treatment   As described in Chapter 3.3.1, the surface of the boat is a gel coat that serves as a                                    protective finish to the hull. The main purpose is to prevent damage from abrasions and the                                penetration of moisture. It is a polyester resin with a higher viscosity and hardness than a                                standard resin. This allows for both easy application and increases the structural integrity of the                              fiberglass material. These properties are due to the use of Isophthalic/Neopentyl Glycol                        (ISO/NPG) resin.  8 
  • 10. The Coating is applied by a relatively simple process. First the surface is prepared by                              sanding any imperfections smooth, then cleaning any debris, oil, or paint that may inhibit                            adhesion. Next, the gelcoat, catalyst and tinting are mixed together and are now ready for                              application. This can be done either with a sprayer or roller. It is important to sand between                                  layers as this allows for proper adhesion. The curing process takes between four and six hours                                before a final hardness is ready[15].    4. Comparison    To make a comparison between ancient traditional Hawaiian canoes and modern canoes,                        several factors must be taken into account and looked at both objectively and subjectively. On                              the surface, it is easy to say that modern canoes are far superior to ancient canoes, for that is                                      indeed the goal of the evolution of manufacturing ­­ to improve upon a product. However, from                                an objective point of view, the factors that will be discussed and compared are materials,                              manufacturing methods, production time, performance, and expected canoe life. From a                      subjective point of view, artistic quality, value and use will be discussed.   The evolution of the materials used to construct racing canoes has resulted in lighter,                            stronger, and faster canoes. The weight­to­strength ratios are much higher with modern canoes.                          This is not to say that the ancient Hawaiian canoes were not strong, but they were much heavier.                                    With modern methods of manufacturing, not only has the time to construct a canoe been                              drastically reduced, but the product consistency has increased. Ancient canoes varied from one                          another due to factors such as tree size, location of knots, and wood grain. Although the methods                                  were similar, every craftsman made them a little different, to the point where each canoe was a                                  unique creation.  The performance of modern canoes not only improved, but using modern computer                        design programs such as SOLIDWORKS, the performance changes and hydrodynamic                    properties can be predicted by using mathematical formulas, and studied without a                        “trial­and­error” approach that would have been otherwise needed to test each canoe                        manufactured. Since a new canoe is not needed each time to test performance, there is less waste                                  of material and time.   These factors however, do not necessarily mean modern canoes are superior to ancient                          canoes. Modern canoes for example, have an average life of approximately ten years due to a                                phenomenon called blistering which delaminates the material. This is caused by water getting                          under the gel coating. The life of the canoe can be extended with proper care, such as fresh­water                                    rinses when not in use, complete drying, and minimizing exposure to direct sunlight. However,                            traditional canoes (made of wood) can in many instances last much longer.   From a subjective standpoint, the reasons for using canoes have evolved just as the                            manufacturing has, and it would not be fair to say that modern canoes are superior. Ancient                                Hawaiian canoes had much more uses than modern canoes and were valued by the Hawaiians.                              They were unique pieces of art as well, and  symbols of the communities that built them.  9 
  • 11. 5. Conclusion   The focus of this research was an analysis of the materials and manufacturing process                            involved in the building of traditional Hawaiian and modern single hulled outrigger canoes with                            the ultimate goal to compare similarities and differences. By applying modern theory on the                            manufacturing processes to such a specific and local product with tremendous cultural history,                          we were able to identify some of the indigenous knowledge of ancient Hawaiian culture, as well                                as some of the modern advancements in composite manufacturing.   In summary, our research showed that traditional canoes were carved out of Koa wood,                            then cured, and their surface treated with natural oils and paint to improve the material                              properties, mitigate fatigue life, and ensure longevity of the canoe. Modern manufactures on the                            other hand strive to design and build lighter, stronger, and faster canoes by optimizing their                              designs through simulation software (computer software), composite materials, and composites                    manufacturing techniques such as vacuum bagging.   An objective and subjective comparison showed that there are parallels in the                        manufacturing processes and that modern canoes are still modelled after ancient designs. While                          mechanical properties and the manufacturing processes are far superior to traditional ones in                          terms of weight, strength, and production time, the cultural value, uniqueness, and the ancient                            engineering knowledge embedded in a traditional Hawaiian outrigger canoe are remarkable.           10 
  • 12. Appendix A  A.1 Tables     Table 2:​ ​CFRP Material Properties based on a weight ratio of 60% carbon fiber to 40% epoxy resin​[9].  Carbon Fiber Reinforced Polymer  (CFRP)  Test Results  Comments  Density (kg/m³)  1.79g/cm3    Tensile Modulus  245 GPa  ASTM D3039  Tensile Strength, Ultimate  4620 MPa  ASTM D3039  Elongation at Failure  1.8%        Table 3:​ ​S­glass Properties​[9].  Owens Corning S­glass  Test Results  Comments  Density  2.49 g/cm​3    Tensile Modulus  88 GPa  ISO 527­5  Tensile Strength  1550 MPa  ISO 527­5  Poissons Ratio  0.27  ASTM D638 ­ 0.27      Table 4: ​Divinycell Material Properties​[11].  Divinycell H80  Test Results  Comments  Tensile Strength, Ultimate  2.20 MPa  ASTM D1623  Elongation at Break  18%  Shear Strain  Tensile Modulus  0.0800 GPa    Compressive Strength  1.20  ASTM D1621  Compressive Modulus  0.085 MPa  ASTM D1621­B  Poissons Ratio  0.032    Shear Modulus  0.03099 GPa  ASTM C273  Shear Strength  0.951 MPa  Yield; ASTM C273­00            11 
  • 13.   Table 5:​ ​Coremat Material Properties​[12].  Coremat (2mm)  Test Results  Comments  Dry Weight  96 g/m2    Density Impregnated  540 kg/m3    Flexural strength  8.5 MPa  ASTM D790  Flexural Modulus  1250 MPa  ASTM D790  Compressive Strength (10% strain)  10 MPa  ISO 844  Shear Strength  3 MPa  ASTM C273­61  Shear Modulus  25 MPa  ASTM C273­61      Table 6:​ ​Physical Properties of Cured Epoxy​[13].  Cured Epoxy  Test Results  Comments  Hardness (Shore D)  83  ASTM D­2240  Compression yield  1155 MPa  ASTM D­695  Tensile strength  800 MPa  ASTM D­695  Tensile elongation  3.4%  ASTM D­695  Tensile modulus  41340 MPa  ASTM D­695  Flexural strength  1428 MPa  ASTM D­790  Flexural modulus  46710 MPa  ASTM D­790            12 
  • 16.   Acknowledgements  We would like to thank Kamanu Composites Inc. for offering their support and letting us visit                                their company to observe and learn about their manufacturing process at first hand. We would                              especially like to say Mahalo to Keizo Gates, who went out of his way in showing us around and                                      responding to follow up questions.       Bibliography    [1] Thompson,Nainoa. (undated) `Ike: Knowledge and Traditions Retrieved: April 23, 2015, from           ​http://pvs.kcc.hawaii.edu/ike/intro_ike.html​.    [2] Chun, Naomi NY, Hawaiian Canoe­Building Traditions, Revised Edition, Kamehameha Schools           Press. Honolulu, 1995, pp. 3­39    [3] Skolmen, Roger G. (2000). Some Woods of Hawaii. Retrieved from University of Hawaii, College           of Tropical Agriculture and Human Resources. Retrieved: May 1, 2015, from            ​http://www.ctahr.hawaii.edu/oc/freepubs/pdf/RM­7.pdf    [4] Smithsonian Museum Conservation Institute. (undated). Microscopy: Technical Information Sheet:           ACACIA KOA. Retrieved: May 4, 2015, from   http://www.si.edu/mci/english/professional_development/past_courses_programs/programs/acacia_koa.ht ml    [5] Green, David W., Winandy, Jerrold E., & Kretschmann, David E. (undated). Mechanical Properties           of Wood. Retrieved: May 2, 2015, from          h​ttp://www.conradfp.com/pdf/ch4­Mechanical­Properties­of­Wood.pdf    [6] Polynesian Voyaging Society, “Plants and Tools Used for Building Canoes”, Retrieved: May           4, 2015, from ​http://pvs.kcc.hawaii.edu/ike/kalai_waa/plants_and_tools.html     [7] The Encyclopedia of New Zealand, “Story Waka Ama ­ Outrigger Canoe”, Retrieved: May 6,           2015, from ​http://www.teara.govt.nz/en/waka­ama­outrigger­canoeing     [8] Kamanu Composites. “Reason for being” (2014). Retrieved: Apr. 26, 2015,           http://www.kamanucomposites.com/company    [9]"Hexcel.com ­ HexTow® Continuous Carbon Fiber Products." 2011. Retrieved: Apr. 27,   15 
  • 17.         2015, from ​http://www.hexcel.com/Resources/Cont­Carbon­Fiber­Data­Sheets    [10] “Owens Corning Composite Materials." 2011. Retrieved: May. 3, 2015, from            ​http://composites.owenscorning.com/    [11] “Core Material ­ Diab." 2012. Retrieved:  May. 3, 2015, from           ​http://www.diabgroup.com/Products­and­services/Core­Material    [12] “Coremat® : TAP Plastics.” 2012. Retrieved:  May. 3, 2015, from           ​http://www.tapplastics.com/product/fiberglass/carbon_specialty_fabrics/coremat/93    [13] "Proset Laminating Epoxies ­ PRO­SET Epoxies." 2005. Retrieved: 2 May. 2015, from            ​http://prosetepoxy.com/laminating_epoxies.html    [14] "Physical Properties ­ WEST SYSTEM Epoxy." 2008. Retrieved: May. 3, 2015, from             ​http://www.westsystem.com/ss/typical­physical­properties/    [15]  "GEL COAT: Basic Information ­ Evercoat." 2011. Retrieved: May. 1, 2015, from            ​http://www.evercoat.com/imgs/pis/gelcoat.pdf            16