Appendix M - Boat Designs

			Fat Canoe - East Timor Design ABET http://www.bri.net.au/

This design was developed by NZ designer John Welsford. Here he describes the development process.
My researcher, a New Zealand Army type stationed in East Timor when I contacted her, told me that the locals could not row, they had always paddled, that canoes were the boats that they knew best, and that there was no longer the infrastructure to support fuel supplies and mechanical backup for engines. She confirmed my suspicions that big deep vee runabouts were likely to be complete white elephants, and that the bulk of the boats destroyed were dugout canoes and anything too different would not get used, and if used could have an adverse effect on the fish stocks.
So! It was with all this in mind that I sat down to draw "the" boat. Barry had in mind a kitsetting operation based at his home in Northern New South Wales Australia. He expected to make a couple and send them up assembled to evaluate them, and then send containerloads of flat packs up for local assembly. They needed about 12,000 boats so every shortcut was a help.

There is a plywood mill not far away from Barrys place. As it happened we did not use that mill product but it was to be construction plywood and builders yard lumber. The Old Tradesman made a much nicer job of the boats than I envisaged, pride did not allow him the luxury of a quick and dirty job but it was still not long until the Mk one Fat Canoe was built.
Designed for 5hp, with a sail for reaching and running and narrow enough to paddle she was sponsored by the McLean Shire Council and after launching was filled with relief supplies, not just fishing gear but hospital equipment, bicycles, computers, blankets and tools. All airfreighted up to Dili by the Airforce.
Barry got the surprise of his life when the trip included him, and he went up to do the handover and research the needs of the community.
His description of the ceremony still has him choking with emotion. The people chosen by the UN Fisheries and agriculture officer had come close to starving without the boats that were their means of providing for the village. There are no seabirds in East Timor, all of the eggs for several generations had been eaten, there are no small animals, no edible plants left and no shellfish. All eaten . While for lack of a boat and fishing equipment a sea teeming with fish could not be harvested.
After a voyage of several hours in the Fat Canoe, pushed at about 6 knots by a tiny outboard, “The Boat” and her crew of four were carried bodily ashore by the villagers, and placed reverently under a shade house built to house the new vessel.
It is hard to explain just how important that boat is to those people, a subsistence economy dependent on fishing suddenly deprived of its boats and fishing gear cannot survive, and these people were close to not surviving. I must admit that the letters from the villagers were very very moving.
Barry and I went on to modify the boat, Mk11 was for a 10 hp motor, he went on a step further and altered it further to produce a Mk111 suited to a 15hp motor. There were several hundred 15 HP short shaft Yamaha outboards in a UN store somewhere and all of those were commandeered for the program.
Barrie and Michele-Marie now live in East Timor, teaching villagers how to build the “Fat Canoes” and how to use computers (Michele-Marie's skill). Barrys boatbuilding school has turned out dozens of these simple workhorses, and more importantly quite a team of locals who can build a whole lot more. They can be found all around the coast, and they are worked night and day by teams of villagers who own and operate them on a share basis.
It’s a small thing, the original design took me a couple of phone calls and a few hours at the drawing board. No money changed hands but the rewards have been immense.
Watching how the boats went, and playing with one of the prototypes on the Clarence River near Barry's (then) Northern New South Wales home I was hugely pleased with the performance of the boat. So much so that I have designed a “civilian version of the boat. I tidied her up a bit, specified Stainless fastenings and marine grade adhesives, a better grade of ply and nice paint. As a design it’s a “good un”. She will carry more load, faster on less horsepower than anything that I have ever seen. She is stable enough to stand up in, has enough capacity for a pile of people or gear, and is still light enough to be manhandled.

While the East Timorese use them to chase Tuna many miles offshore in the tradewinds swells as well as inshore fishing, I think that she is particularly suited to estuaries and swamps, tidal flats and inlets. Shallow places and fast currents, beaches and sandbars where the shallow boat with her protected motor will perform at her best.
She can be built shorter simply by leaving one frame bay out, and these 16 footers have proven both popular and economical, as well as fitting most peoples idea of proportion. Me? The efficiencies of the longer boat would convince me to build her as drawn.
This is a lot of boat for not much work, and very little cost, one which would perform as well in the winter with guns and dogs as she would in the lazy heat of summer with the offspring hanging their lines over the side while you laze in the shade.
John Welsford Designer
NZ $185 00
US $125 00
Australia $170 00
Euro €95 00
Sterling £ 65 00

Clarence River Dory Plans

			Center for Appropriate Technology (CAT) Plywood Boats in India

			One after another in the fishing villages along the lower south-west coast of India, a vast array of traditional craft are being rapidly replaced by colourful plywood boats which can be fitted with out-board motors. John Kurien describes this transition, which began as a ripple in 1982, and became a tide in 1995, with about 5000 new boats in operation. Invention to innovation Major innovations are very often preceded by slow and continuous experimentation. This was the case with the launching of the first prototype plywood boat in 1982, which followed a decade of experimentation, initiated in 1973 through the Indo-Belgium Fisheries Project (IBFP). One of the first activities of the IBFP involved the training of youth from the region in boat-building skills. A boat-building yard was set up at Muttom, a fishing village at the tip of the Indian peninsula. But the good quality fibreglass (FRP) boats built as a part of the training did not interest the majority of the fishermen of the region, who used kattumarams and canoes for fishing. The boat-builders then began to make flat bottom plywood boats, but these did not arouse the curiosity of the fishermen either, since the boats needed mechanical propulsion and the initial costs were still relatively high. The boat- builders soon learned that although they could make quality boats, they could not sell them. Pursuing the 'prototype' approach to innovation diffusion without a keen understanding of the needs of the market contributes more to boat design history than to solving technological problems. The project soon restructured. The research and development (R&D) activities were split from the boat manufacturing activities. The latter was handed over to the trainee workers to be managed as a commercial venture, and was renamed Boat Building Centre, Muttom (BBC Muttom). The former became the Centre for Appropriate Technology (CAT) - reflecting the new understanding of technology in relation to society. The R&D initiatives at CAT were soon concentrated on finding an appropriate technological solution to fit the needs of the local artisanal fishermen. Pierre Gillet, the Belgian engineer who initiated the boat-building project, recruited to CAT It had to provide more carrying capacity, be more comfortable than a boat powered by sail and oar, have a lifespan of 7 to 10 years, and be within the financial reach of the fishermen. Parallel to this development in CAT came an offer to the BBC Muttom from British naval architect Edwin Gifford and the Intermediate Technology Development Group (ITDG) to build and test some prototypes of a new beach landing craft fabricated in marine plywood using a technique called 'stitch and glue' (see box). Gillet saw that this boat-building technology could be key to realising their own ideas, and accepted the Gifford-ITDG proposal. Mr. F.M. T. Raj, better known as Raju. Raju, an educated fisherman who had worked on the traditional crafts, had experimented on the new boat designs that were built before 1978. Together they set out to build a new craft to replace the kattumaram. The technological parameters for this new R&D venture were clearly laid out. Like the kattumaram, the new craft had to be unsinkable, light, and easy to operate from the surf-beaten beaches. It had to provide more carrying capacity, be more comfortable than a boat powered by sail and oar, have a lifespan of 7 to 10 years, and be within the financial reach of the fishermen. Parallel to this development in CAT came an offer to the BBC Muttom from British naval architect Edwin Gifford and the Intermediate Technology Development Group (ITDG) to build and test some prototypes of a new beach landing craft fabricated in marine plywood using a technique called 'stitch and glue' (see box). Gillet saw that this boat-building technology could be key to realising their own ideas, and accepted the Gifford-ITDG proposal. Having mastered the new technology, the plan for the 'ideal' craft was revived. News of the new craft spread rapidly along the coast by word-of-mouth, and the cost of Rs7500 (in 1982 prices) seemed well within the reach of the fishermen. Firm orders from kattumaram fishermen was proof of this. The instant success of the 'kottarkat' made BBC Muttom and CAT more confident and open to the requests from other fishermen using different types of traditional crafts. The next request came from fishermen who wanted a replacement for their dug-out canoes, as large tree trunks were in very short supply as a result of heavy deforestation. A plywood vallam (see photo) made using the stitch-and-glue technique was a possible solution. It would have to be stable, with good rowing and sailing efficiency, and be able to take an outboard motor (OBM). Box 1. Traditional Fishing Craft of South-west India By the end of 1982, BBC Muttom had designed a new plywood vallam and had outstanding orders for 26 kottarkats. The rising demand for the new boats was a reflection of both the technical soundness and the commercial viability of the boat yard. An old experiment was slowly turning into a successful innovation. Promoting the innovation The enthusiasm of the fishermen for the new plywood boats was also the result of several supply and demand factors not directly related to Muttom. · First, there was the decline in the amount of fish landed by the artisanal fishermen between 1975 and 1980. The fishermen attributed this to the destructive fishing of the trawlers. · Secondly, as a result of this perception, there were conflicts at sea, and trawlers were attacked. But artisanal fishermen felt that it was not enough to curb the trawlers, they had to fish better too. Mechanical propulsion was the only way to achieve this. · Thirdly, the government's liberal 1980 import policy resulted in the availability of OBMs in the open market. · Fourthly, the price of traditional craft spiralled because of the acute shortage of light Wood and large trees. Fishermen who were still using the centuries-old craft design became more open to adopting new models and using new materials became commercially feasible . By early 1983, these macro conditions and the situation along the south-west coast region combined to really launch the PWB commercially. In fact the demand for the plywood boats brought with it a host of new, unanticipated supply problems. The need for the present boatbuilding set-up to work commercially raised a number of questions: What institutional framework would allow expanded activity in the future? How should finance questions be resolved? Should the designs be patented to ensure that the new technology remained in the control of those who had the interests of the fishermen in mind? BBC Muttom, CAT, ITDG, and Gifford discussed these issues with the South Indian Federation of Fishermen Societies (SIFFS), a non-government federation of fishermen's organisations. Following this the patent rights were transferred to SIFFS and they granted BBC Muttom the status of associate member, thus beginning a new form of more structured institutional linkages and initiatives to diffuse the technology. SIFFS opened a small boatyard in the fishing village of Alljellgo in January 1983, and started producing the first kottarkat models before specialising in the plywood vallams. New inventions are never perfect at first, and may initially offer only very small advantages over previously existing techniques. The rate and extent of diffusion will therefore depend on the experience of the initial adopters, the availability of related complementary innovations, and the improvements made to upgrade the existing technologies. Just before their first monsoon, in May 1983, the kottarkats were showing signs of 'disease': the fibreglass tape was giving way, and cracks and leaks were appearing in the hulls. A drop in new orders was followed by a wave of cancellations. This brought panic. A crisismanagement strategy was adopted to ensure quick repairs of all the affected boats. An assessment of the situation highlighted the cause: an unanticipated usepattern. The fisherman were using 7 horse power outboard1 engines with the full crew sitting at the stern. The front of the boat was pounded on the waves, causing most of the damage. But the fact was that quality standards had also been lacking. The initial bad reputation earned as a result of the faulty craft was more than made up for by the repair campaign. The close interaction between the boat owners and the BBC Muttom workers during this campaign on questions regarding craft design, materials, and construction became an important component in the plans for new models. The crisis was thus turned into an opportunity, which led to design improvements which would not have materialised so quickly during 'the normal course of diffusion'. Complementarity The boat-builders did not realise the strong complementary role played by OHMs in the diffusion of PWHs. Their target was to replace 20 000 kattumarams, but in actual fact it was the number of kattumarams (and later canoes) that could be fitted with OHMs which was to decide the ceiling. In 1983 this number was a mere 200 units. In a sense, therefore, the diffusion of the OHMs. A single technological breakthrough rarely constitutes a complete innovation. The introduction of new innovations also seems to result in immediate improvements in the old technologies. As OHMs were adopted much more quickly than the PWBs, the majority of the fishermen had to attach their new motors to their kattumarams and canoes. The vibration from the OBM strained the rope-lashed logs of the kattumaram and the coirstitched canoes, so the fishermen improved the structure of their craft to reduce the vibration. These changes spread epidemically, and in one sense reduced the demand for the PWBs. Alternatively, it may also be seen as a process which smoothed the transition from a traditional technology to a more modern one. While this factor may have retarded diffusion, the expectations of profits or larger incomes as a result of greater investment and better use of capital tended to promote it. An assessment of the economics of the operation of the plywood boats compared to the motorised and sailpowered kattumarams was undertaken in 1983. From the study, it was evident that both crew and owners of PWBs, who had paid 20 to 25 per cent more for their craft, earned substantially more than the crew and owners of the motorised kattumarams. The commercial feasibility of using PWBs was thus established by the end of 1984, and because of liberalised import policies and financial support from banks, OBMs were more easily available in the market. The result was a sharp increase in the demand for PWBs:

			Small Cat & Rig Design

Design:Requirements & Concepts

Functional Requirements
•

• Design Parameters
• Crab Claw Sail
• Bipod Mast
• Weight & Sail Area
• Hull Shape

Functional Requirements:
    While designing my cruising beach cat, I had one thing on my mind... EASY. Although there is nothing like sailing a high performance beach cat, they can be a hand full both on and off the water. So I set out to build a cat that would increase my fun to work ratio by making the boat easy to deal with on the beach and on the water, and if that meant that some speed had to be sacrificed, so be it. The requirements were simple:
1. Fast, easy setup from a trailer
2. Good cruising performance in moderate conditions
3. Controllable in heavy conditions
4. Reasonably cheap and easy to build
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Design Parameters:
    To accomplishing these requirements I combined two concepts:
1. Light weight 14' boardless tacking catamaran
2. Polynesian style crab claw sail
    I decided on a 14' hull because the boat had to be easy to handle on land and this was my first boat building project so I wanted to keep it small. I think next time I'll go with 16' because the plywood for the hulls comes in 4' x 8' pieces and so 16' is the biggest you can go with only one scarf joint.
    I found information on the crab claw rig through some internet searching and it seemed the perfect fit so I decided to try it out (see following section on the crab claw).
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Sail (Why the crab claw?):
    The popular Bermudan sail with rotating mast featured on most production catamarans exhibits great upwind performance, which is why it is so successful on racing boats where upwind performance is king, but it does have several drawbacks:
1. The mast and sail are expensive to manufacture
2. It has a relatively high center of effort (undesirable in heavy winds)
3. It's downwind/reaching performance is inferior to several other rigs
    The Polynesian crab claw overcomes all of these drawbacks at the cost of some upwind performance. Since the crab claw requires simple round spars for the mast, boom and yard I could make them myself from carbon fiber and fiberglass. And the crab claw sail works best when it is cut perfectly flat, so I could do that myself too. In addition, this rig doesn't create loads as large as those of the Bermudan rig and so all of the components can be made lighter.
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Bipod Mast:
    Prior to this project I had no experience with crab claw sails (other than on a sailfish) or a bipod mast, which allows the crab claw to tack without the mast distorting the sail shape. Below are pictures of the sail plan I used and a scale model I made to figure out how the rig, with bipod mast, would be set up.

    The analysis of the loads on the bipod mast is an interesting one. Because the base of each mast is connected to hulls, and not in the center of the crossbeam, the shrouds (also connected to the hulls) have no ability to pull sideways on the mast the way a traditional rig does. Instead, the shrouds (one head stay and one back stay for each mast) only serve to control the fore/aft tilt of the masts (which can be easily adjusted to move the sail's center of effort). When the sail forces push sideways on the masts, all of the lateral force is turned into compression of the leeward mast and tension in the windward mast. A static analysis of these forces is linked below:
Free body diagram analysis of the mast forces.
Since long slender structures tend to buckle under large compressive loads, the masts have to be very strong to avoid failure, which is why I chose to construct the masts out of carbon fiber. My masts are approximately 12' long and 2 1/2" in diameter with a 1/8" wall thickness. Ideally, they would be very small with a airfoil cross section to minimize their aerodynamic drag. I may eventually try to fit a thin foil shaped shell over the masts to reduce the drag if it seems worthwhile.
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Weight & Sail Area:
    Weight on any catamaran is paramount. Any design becomes instantly faster whenever a significant amount of weight can be eliminated because weight relates directly to hull drag. With this in mind, I set out to make the hulls (the biggest component) as light as possible. The best method of construction available was tortured plywood construction because it does not require a mold, is relatively inexpensive and results in a very light hull. Based on the density of plywood and the hull design, I estimated that I could create a 14' long plywood hull weighing less than 50 lb with a total boat weight of under 200 lbs.
    Next, I wanted to estimate the sail area I would need. To do this, I examined the specifications of various beach cats summarized in the table below. When comparing the sail area of different size boats, it is necessary to calculate a dimensionless parameter such as:

sail area/displacement^(2/3)

Since a boats displacement (weight) increases as length^3 while sail area only increases as length^2 this parameter will yield a number that can be used to compare boats of different sizes. To have something to compare to, I gathered specifications on various production beach cats and summarized them in the table of below (Crew weights listed are the minimum class weight for racing. If there is no class weight I assumed 150 lb for single handed boats).

As you can see, I found that for all the boats under 16' in length, the average value of this sail area-displacement parameter was about 34, giving a sail area for my boat of about 100 square feet.
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Hull Shape:
Being partial to nacra hull designs, I modeled my hulls after the nacra 5.0 (sharp tall bows with a rising stern and a long skeg instead of dagger boards). But before I started cutting, I did a little analysis of different hull shapes. To estimate the relative amounts of drag on different shapes I calculated the wetted surface for a given displacement/weight per unit length. The results shown are the relative amount of wetted surface area for the various shapes normalized to the results for an ellipse, which had the lowest value. Therefore, the smaller the number, the lower the wetted surface area. For example, the triangular hull shape has 2.4 times as much wetted surface as the ellipse (for all shapes except the circle, the aspect ratio 'height/width' = 2:1 representative of the middle portions on the hull where most of the buoyancy is located).

    This analysis shows that for a hull of uniform cross section floating in still water, the ellipse has by far the least amount of wetted surface for a given displacement/weight. It also shows that the triangular hull shape is by far the worst. The rest of the shapes are comparable. However, minimizing wetted surface area is not the only consideration when designing a hull. Since in reality the hull will be traveling through waves, a sharp hull shape will offer less wave resistance and a smoother ride. Based on these results I decided that the nacra hull shape (closest to the ellipse) was indeed the best shape and so I stuck with it.
    However, it does seem that the curved triangle shape, while it does possess an 80% increase in wetted surface area, could produce a very smoothly riding hull that would not require a skeg or dagger board and the extra drag associated with such foils (see the G-cat design). This shape seems to have a lot of potential for a cruising cat and after seeing how hard it can be to bend plywood around tight radii, I can appreciate how much easier it would be to build using plywood.
    Here is a Pugh chart weighing each shapes pros & cons with my own weighting system, looking back now, I think I would go with the curved triangular hull if I build another cat.

To contact me write to kseluga@rclandsailing.com