1 Boat Design, Construction, and Propulsion

Traditional fishing vessels have evolved to complement the sea conditions and fishing methods unique to each particular region. Like fishing gear, boats have passed the test of time. Nevertheless, traditional craft are not without their problems. They often have a very limited range of operation and are not able to go beyond heavily fished nearshore areas. Many will sink if swamped, providing no reserve of safety. Customary building materials are often unavailable. Deforestation in many coastal areas has created a scarcity of quality wood for dugout canoes and larger craft.

Traditional boats can be improved, often without radically altering the basic design; a respect for tradition will increase their acceptance. New vessels should have improved fishing capabilities. Increased seaworthiness and better fuel performance would permit fishing further offshore for previously unexploited species. Working and storage space could be increased, creating better working conditions and facilitating an increased catch. In areas without harbors, beachable craft are a priority. Improved designs should also help ensure the safety of the crew by including a second means of propulsion and sufficient buoyancy so that the vessel remains afloat when flooded.

Cost effectiveness is a fundamental requirement. The value of the daily catch must exceed the operational costs and help amortize the construction costs within a reasonable time. In essence, the boat should require low investment, use minimum fuel, catch as much fish as possible, and have a long service life.

This chapter covers some design considerations, examines some new boat construction methods and materials, and describes a few propulsion techniques.

DESIGN

A fishing boat may be described as a floating platform used to transport the crew, gear, and cargo to and from the fishing grounds and to support the crew and equipment during the fishing operation.

Some of the major factors that affect the design of this platform include:

· Available funds

· Available materials

· Skills for building and maintenance

· Size limitations dictated by water depth or requirement for beaching

· Distance to fishing grounds

· Fuel costs

· Type and quantity of gear used

· Vessel speed requirements

· Number of crew, standard of accommodation, cooking facilities

· Methods of bait and catch preservation

. Safety features.

Usually when a decision is made to introduce new equipment to an existing fishery, the purpose is to fish for a new species or to fish in a new area. New boats, new gear, or both may be needed. In some fisheries, it may be necessary to introduce a few larger vessels. Unless a cooperative system already exists, serious problems of equity can arise when a small group gains significant advantage in productivity through access to new large vessels. The introduction of small, high-speed outboard-motor-powered boats has also brought its share of problems. When the costs of fuel, motor repair, and replacement reach a significant percentage of the fisherman's income, the attractiveness of speed diminishes.

Small craft design should be based on the traditions of a given region. Vessel sizes and designs that have evolved in an area are usually well adapted to the local fishing gear and methods, the range of operations, construction materials, the winds, and local sea conditions. A radical departure from the traditional hull design may not gain local acceptance.

Rafts are keelless vessels that are common in many areas of Asia. They may be constructed of bamboo, logs, or plastic cylinders, lashed or fastened together. These vessels are beachlanding craft, well suited for heavy surf conditions that would exclude many other boat types.

The kattumaran of South India is a wooden log raft that ranges from 3 to 9 m long. Each log is individually shaped with a definite fore and aft curvature. Longer logs are placed inboard and shorter ones outboard, and all are lashed together. Planking is then nailed over the logs to provide a smooth working surface.

Single-hulled vessels are most commonly used in small-scale fisheries. Designs with a high length to beam width ratio and a low displacement (Displacement: the weight or volume of water displaced by a boat) to length ratio have less resistance per unit of displacement than do fat, heavy hull forms.

FIGURE 1.2 This FAO-developed 8.7-m boat was specifically designed for village fishery use.

Therefore, narrowing the beam, lightening the draft, (**Draft: the depth of water that a boat displaces) and decreasing the displacement length ratio will result in less fuel consumption at a given speed.

A number of FAO-designed hulls based on these principles have been adopted in the South Pacific. The FAO 8.7-m boat (figure 1.2) has been designed as an easily propelled, narrow beam, light displacement craft suitable for village fishery operations. An outboard-powered model of this craft has been built in Western Samoa for US$1,250. With a crew of 4 and a 200-kg catch, the vessel can achieve a speed of 10 knots with a 20-hp outboard motor.

Multihulled vessels, such as catamarans and trimarans, have traditionally been used as fishing boats in the Pacific Islands. They show promise as fishing boats in other areas, especially where fishermen use one or two outriggers and are accustomed to the idea of multihulls.

Multihulled boats have a number of positive features for small-scale fisheries. Their hulls have low displacement to length ratios and high length to beam ratios (long and narrow) and therefore offer minimum resistance and are easily propelled. Moreover, the stability of multihulls makes them ideal candidates for sail power Small catamarans are lightweight and can be beached and carried with relative ease.

Several development projects are attempting to introduce small fishing catamarans and trimarans into areas that traditionally have used monohulls. A number of catamarans have been introduced into the tropics by Gifford and Partners of Southampton, England. One of them, the Sandskipper 24 , is gaining acceptance in Sri Lanka as a beachable fishing vessel. It has a lateen sail and a diesel engine as propulsion options. This vessel design has proved very satisfactory for gill netting. It can carry a ton of gear and up to 2 tons of catch in good weather.

CONSTRUCTION

Traditional dugout canoes and bamboo rafts are common throughout the Third World. The construction materials are usually inexpensive and available locally. However, both materials severely limit the hull shape and are relatively short lived. Wooden logs are heavy and can result in high fuel consumption. While bamboo has the advantage of being lightweight, it is not especially durable.

Wood and bamboo will remain important boat building materials in coastal fishing villages where they are readily available. Where there is a scarcity of good wood, there may be no alternative to adopting new materials. Newer materials and methods can offer many advantages that compensate for their increased cost. The choice of material will depend upon a number of factors including cost, availability, longevity, ease of repair, strength, and resistance to corrosion and rot.

Wood Construction

Timber

Planked hulls have been constructed for hundreds of years throughout the world, and in many areas they are still very popular and highly regarded. Nevertheless, their importance is clearly diminishing as new construction materials are accepted.

Several variations of planking are commonly used. In carver planking, the outside planking is laid edge to edge, giving the hull a smooth surface. If the planks are very narrow (2.5-4 cm wide) and wedged together with the edges fastened, the method is called strip planking. Marine glue or caulking is used to keep the seams watertight.

In clinker planking, each plank overlaps the upper edge of the plank below and is attached to it by nails driven from the outside. This variation is strong and flexible and is ideal for such small craft as dinghies.

Wood can be a very satisfactory boatbuilding material: it has good resistance to chafe, gives thermal and acoustic insulation, and allows great variation in hull shape. If good timber is available locally and is economical, it is a logical choice. However, in many tropical coastal regions, suitable boatbuilding timber is scarce and expensive. Another disadvantage is the high degree of skill required to build a wooden boat. With only hand tools, construction can be very time-consuming. The hulls produced are of medium weight and, as they become increasingly waterlogged with age, consume large amounts of fuel. Many woods are also subject to rot and attack from marine borers.

In Tahiti, V-bottom bonitiers are built of imported redwood planking with local timber used for the frames. Hot dipped, galvanized carver nails are used for the fastenings. These boats are reported to last well, in spite of being stressed when they are run at high speeds.

Plywood

Plywood is a sandwich of wood veneers and filler material held together by adhesives. There are many grades of plywood, but generally, marine plywood made with a waterproof adhesive is required for boatbuilding. Lower grade plywoods can sometimes be upgraded for marine use if they are coated with a polyester resin.

Plywood is very adaptable to small boatbuilding operations.

It is light, can be cut to any shape, and is easily bent. Since sections are cut from large plywood sheets, there are fewer seams than in planked boats. Plywood construction involves building a framework for the hull from planks and then attaching sections of marine plywood to this frame. The plywood hull is held together by nails; marine glue is used to seal the seams.

Plywood boatbuilding can be quick, inexpensive, and easy. As long as the surface, and especially the edges, of the plywood are treated with epoxy resin or another sealer, the boat will have a long life. However, the use of plywood does restrict the hull to hard chine shapes, such as flat or V-bottomed boats. Moreover, its resistance to chafe is not high.

There are many successful examples of plywood boats built and used throughout the world.

Some 250 plywood versions of the Alia, an 8.5-m fishing catamaran, were built in Western Samoa in the 1970s and have survived almost a decade without hull rot or delamination. These vessels have an emergency sail but rely on outboard motors as their principal method of propulsion. Fishermen generally employ these catamarans for trolling and handlining. In Fiji, more than 130 V-bottom fishing boats (8.6 m) have been constructed of plywood. They are equipped with inboard diesel motors and are also used primarily for handlining and trolling.

A plywood single outrigger canoe was designed by FAO in 1985 specifically for the waters of Papua New Guinea.This 7-m canoe is sail-assisted and is designed to use an 8-hp outboard motor. The outrigger is filled with foam and helps support the weight of two or three persons in the canoe. In sea trials it was shown that this new vessel equipped with an 8-hp outboard engine was faster than a traditional dugout, powered with a 25-hp engine, and could travel about twice as far on the same amount of fuel. Similar plywood outrigger canoes (proas) have proved their worthiness throughout the South Pacific where they can replace canoes made from timber.

Plywood skiffs have wide acceptance throughout the world as inexpensive, rugged work boats. In southern New England (United States), plywood skiffs are extremely common and are used for lobstering, trawling, and gill netting. With good waterproof adhesives, these skiffs can have a 15-year service life.

Marine plywood is also used in the stitch-and-glue technique (figure 1.7). Precut sections of plywood are wired together with galvanized wire; the seams are then sealed with epoxy resin. The final connection is made by bonding the epoxy resin glue with glass fiber. Once the resin has set, the wires can be cut and a finish applied. The product can be a strong, light boat with a life expectancy at least as good as traditional timber vessels.

Boat construction by this technique is easy and fast. Precut sections of marine plywood may be assembled in a village workshop without sophisticated equipment. Skilled carpenters are not required, but it may be necessary to import the epoxy resin and glass fiber.

This boatbuilding technique has been introduced at the Muttom Cooperative Boatyard in Tamil Nadu, southern India, in cooperation with the Intermediate Technology Industrial Services of England. A number of different designs have been constructed to satisfy coastal conditions, crowded beaches, and the need for more space to carry nets.

Another new boat design constructed by stich-and-glue methods is the ply vallam. Traditional vallams are dugouts made from large mango trees. Having narrow hulls with limited stability, they are almost impossible to sail windward except in very light winds. Ply vallams are wider at the gunwale than traditional boats and have increased stability. This permits the fishermen to sail in any direction with increased safety, thus boosting their fishing potential. Cheaper than the traditional craft, it has been well accepted by fishermen. The ply vallam is now in service at Quilon, Kerala State, South India.

Double-hulled boats have been constructed by stitch-and-glue methods. They can be landed on the beach and offer stability and a large platform for fishing. One small version, the 4.8-m Sandakipper, was also introduced into South India (figure 1.9). It can carry half a ton of gill net and an additional ton of catch.

A plywood houri has also been designed as a replacement for the dugouts and planked houris of the Indian Ocean (figure 1.10). Built from only 4 sheets of plywood, it can be rowed, paddled, or powered with a 4-hp motor.

FIGURE 1.7 The stitch-and-glue construction method involves wiring plywood sheets together, sealing the joint with epoxy resin, and finishing the seal with fiberglass tape and additional resin.

FIGURE 1.9 Double-hulled boats also been constructed by the stitch-and-glue method. This 4.8-m boat has been introduced in south India (E.W.H. Gifford)

Cold-Molding

The boat-construction technique known as cold-molding uses veneers or thin plywood strips to build up a laminated hull. The veneers are applied in diagonally opposed layers. The thickness of the veneers varies in proportion to the hull size, but typically they are from about 2 mm to about 10 mm thick. These thin boards can be produced by a plywood mill or with a band saw or circular saw.

One cold-molding method involves fabricating a mold that provides surfaces on which the planking is stapled. The veneers must be carved to a shape that will fit with their neighbors. The first layer of veneer is stapled longitudinally to the frame.Epoxy adhesive or another gap-filling glue is applied to this first layer, and a second layer of veneer is stapled diagonally over the wet, uncured glue.A third layer of veneer may be placed diagonally to the second.

FIGURE 1.10 A plywood houri has been designed as a replacement for the planked houris of the Indian Ocean. It is Intended to be built using only four sheets of plywood. (E. W. H. Gifford)

After lamination has been completed, the frame can be removed and the staples clipped. The gunwale and keel are then attached. If necessary, a fiberglass-epoxy resin coating can be applied inside and outside the hull. A water-repellent preservative or paint will protect the wood satisfactorily.

The cold-molding technique creates a very light and strong hull, resulting in low fuel consumption. These relatively thin hulls are not highly resistant to puncture but this can be improved by increasing the fiberglass-resin layer. Although in most areas it is probably easier to obtain veneers than good timber, the adhesives may have to be imported.

"Constant Camber" is an improvement on this lamination technique. It requires a reusable mold shaped like a curved trellis. The hull geometry is such that the veneers can be precut and can be easily mass produced. Each veneer strip does not have to be hand carved to fit perfectly vith neighboring pieces.

Another great advantage is that one mold can produce various hull sizes and types.

The mold is best suited to hull forms that have a relatively constant amount of curvature throughout, such as the long narrow hulls of multihulled vessels. However, wide-body hulls can also be produced, and craft as long as 19 m have been fabricated.

Using the Constant Camber process, the veneers are bent diagonally across the mold and stapled, as in cold-molding. Additional layers are held by epoxy resin and can be applied immediately. No screws or nails are required in the process. The staples can be left in and later cut and sanded down.

Alternatively, a process called vacuum bagging can be used to eliminate the need for staples. The defects in the wood are filled with glue and even imperfect wood can be substantially strengthened. The reusable equipment for vacuum bagging costs about $500.

The resulting veneer-epoxy composite is stronger than the original wood itself. The hulls are strong, light, waterproof, and rot-resistant, and have a predicted life of 20 years.

A 35-foot panel can be laminated by several people in a matter of hours. Two half-hull panels are then sewn or glued together to form the hull. Plywood or veneers of fast-growing woods could be obtained locally in many Third World villages and the molding technique learned by village craftsmen. Liabilities are the lack of expertise in using this relatively sophisticated method.

The Constant Camber technique has been used to construct a fleet of 100 paddle-powered catamarans used by Burundi fishermen on Lake Tanganyika. These boats are especially energy efficient because they are easily paddled. A local wood was used for the veneers, but most of the equipment and adhesives as well as the expertise had to be imported.

In Tuvalu in the South Pacific, several Constant Camber catamarans transport people and cargo around the atoll lagoons. These boats were originally financed by the Save-the-Children Federation but are now self-supporting. Over 100 smaller wood-epoxy boats have recently been constructed there.

Non-Wood Construction

Ferrocement

Ferrocement is the term used to describe a steel-and-mortar composite material.It differs from conventional reinforced concrete in that its reinforcement consists of closely spaced, multiple layers of steel mesh completely impregnated with cement mortar. Ferrocement can be formed into sections of less than an inch thick. Ferrocement reinforcing can be assembled over a light framework into the final desired shape and mortared directly in place.

Ferrocement boats are usually constructed close to the water's edge because of their weight. The building site should be chosen with the size of the craft, its draft, and its launching in mind.

There are five fundamental steps in ferrocement boat construction:

(1) The shape is outlined by a framing system.

(2) Layers of wire mesh and reinforcing rod are laid over the framing system and tightly bound together.

(3) The mortar is plastered into the layers of mesh and rod.

(4) The structure is kept damp during the cure.

(5) The framing system is removed (unless it has been designed to remain as part of the internal support).

There are several ways to form the shape of the boat. A rough wooden boat can be constructed as a matrix or an existing, perhaps derelict, boat can be used. Pipes or steel rods may be used to frame the shape of the hull. In the construction of Chinese sampans, a series of welded steel frames and precast ferrocement bulkheads are erected. Layers of wire mesh are then attached to this framework and mortar applied. The steel frames and ferrocement bulkheads are left in place as part of the boat structure.

Using these and similar techniques, ferrocement boats from 8 to 20 m long have been constructed. Above and below this size range there has not been enough experience to recommend this type of construction. Ferrocement hulls less than about 8 m are usually heavier than comparably sized hulls in wood, steel, or fiberglass. This characteristic also prohibits ferrocement use in multihulled vessels.

Problems with chafing, penetration by sharp objects, and saltwater corrosion of the steel mesh have also been reported. Perhaps the most positive aspect of ferrocement as a construction material is the very low cost of materials. A high percentage of materials can usually be obtained locally. Construction is straightforward and rapid.

Any desired hull shape can be produced in ferrocement. Because the hull is homogenous, there are no seams to leak. Damage from impact simply requires chipping away the broken concrete, reshaping the mesh support, and applying new cement. The repair process is easier and cheaper than repairs for many other materials.

Ferrocement boats have been constructed and operate in Southeast Asia, South Asia, the South Pacific, and Africa. Many of these boats have been pilot projects, but in some cases, ferrocement has become a leading boatbulding material.

In 1969, Cuba began construction of its first ferrocement model. During the subsequent 15 years, ferrocement has become the favorite construction material for Cuban boats. Cuban shipyards and the Center for Naval Projects and Technology (CEPRONA) have designed and produced more than 1,000 ferrocement vessels-from shrimp boats to large longline fishing boats.

The People's Republic of China has also opted for ferrocement sampans for use on inland waterways. Thousands are now in use on China's Grand Canal.

Plastic Tubes

Rafts in Taiwan have been traditionally made of bamboo; although very strong and light, this wood is also short lived The bamboo is being replaced by sealed plastic (PVC) tubes that are 15 cm in diameter. Plastic tubing is durable and inexpensive, resistant to marine borers and rot, and does not react with salt water or become waterlogged. Nevertheless, the vessel design is very restricted.

From 6 to 20 4-m-long pieces of plastic tubing are fastened together to construct the raft. The first meter of tubing at the bow is curved upward at 45° to minimize resistance to the water.

The one-layer type of plastic raft is used in coastal fry collection or in set net operation; the two-layer type is used in drift net or long net fisheries. Inboard diesel motors are generally used to propel the plastic rafts. Sail power seems to have fallen into disuse with this vessel.

Fiberglass-Reinforced Plastic

Fiberglass-reinforced plastic (FRP) has gained increasing acceptability as a structural material for boats since the 1950s. This material was first used for pleasure craft and is now increasingly used to construct fishing boats in the Third World.

FRP is a composite material made of fiberglass and a polyester resin. The fiberglass provides the material's strength, and the resin, which is absorbed by the fiberglass, allows the material to be easily shaped.

After a prototype has been chosen, a female mold is manufactured. A polyester resin gel coat is sprayed onto the mold's surface, and then fiberglass and more resin are used to laminate the hull. After transom and keel reinforcements have been installed, the hull is removed from the mold.

FRP is an outstanding construction material for boats. Virtually any complex hull shape can be created. Because of the one-piece hull structure, leakage is practically impossible. The material is highly resistant to scratching and does not rot, rust, or corrode. Thus, less maintenance time is required, and durability is good. FRP shells have a much higher strength-to-weight ratio than similar wooden shells and are also lighter. The actual boat construction does not require high skills or special tools.

The major disadvantage of FRP is the cost of materials. Fiberglass and polyester resin often must be imported at high cost. The development of the female mold required for production is an additional expense. Repair of the hull in remote areas may also be a problem.

The resin presents some difficulties for the tropics because it must be stored in an air-conditioned room and replenished every 6 months. The fibers and resin also can be hazardous to the health of the workers.

Well-conceived and financed FRP fishing boats can be successfully introduced in the Third World if they are economically feasible. The modernization of the traditional canoe fleet has been a priority in Senegal. A prototype diesel-powered beachable fishing boat constructed of FRP was developed by Yamaha especially for the situation there. The Loa 12.8-m canoe has the same length-to-breadth ratio as the traditional wooden canoe but offers an innovation in the hull. The bow is shaped like a ram's horn to facilitate beach landing and hauling of the canoe. The sea trials of this vessel have been satisfactory.

A smaller model, the Loa 9.2 m ,was introduced to the Comoro Islands and the Malagasy Republic in 1983. This sail-assisted, diesel-powered canoe is meant to be a replacement for the traditional double outriggers (pirogues). The Loa 9.2 m has a double outrigger that adds stability and transfers a characteristic of the traditional canoe that is familiar to fishermen. The outrigger floats are made of FRP and the beams of aluminum pipes. It is not clear yet whether this new FRP model yields improved profits, but its sea trials are very satisfactory.

A similar sort of boat evolution has occurred in Sri Lanka through FAO's Bay of Bengal Program. The traditional oru is a Pacific proa-type vessel with a single outrigger. Built of jak timber, it is seen in sizes from 15 to 40 feet. Because of the shortage of large jak timber, the FAO program designed an FRP our that involves a modification of the hull but retains the traditional rudders and rigging.

In some locations, such as the eastern Caribbean, FRP is also used to sheath traditional wooden vessels to extend their lifetime. The Bay of Bengal Program has proposed to protect the logs of South India's traditional kattumaran with FRP sheathing.

C-Flex

C-Flex is a fiberglass planking that can be used to build boats without the standard mold required for fiberglass-reinforced plastic boat construction.

C-Flex is composed of parallel rods of fiberglass and reinforced polyester resin alternating with bundles of continuous fiberglass rovings. This structure is held together by two layers of lightweight, openweave fiberglass cloth. Each plank is 112 cm wide.

The planks are laid over plywood frames, tacked in place, and covered with resin. Fiberglass mats are then applied at right angles to the C-Flex. Sanding and a final finishing complete the process.

C-Flex offers all the advantages of FRP as a construction material, except that the strength-to-weight ratio may not be quite as high. No mold is required, which greatly lowers costs and permits decentralized village construction. An additional advantage is that few tools and equipment are required.

Even though the absence of a mold cuts costs, the C-Flex must be purchased through a company in New Orleans (United States). In many locations, the fiberglass and laminating resin would have to be imported, resulting in a costly product.

The International Center for Living Marine Aquatic Resources Management (ICLARM) in the Philippines designed and constructed an experimental small fishing boat using C-Flex. The hull is 6 m long, has a shallow draft, and is beachable. Propelled by an inboard engine, the craft also has a sail-assist option. ICLARM suggests that the fiberglass material accounts for about two-thirds of the cost of supplies.

Aluminum

Construction of small aluminum vessels involves standard metal-working techniques. Aluminum plates are cut and bent to fit the frame of the hull. Welding and riveting are then used to seal the seams and fasten the plates.

Aluminum alloys are excellent materials for small vessels. They can be shaped to almost any hull form and produce a greater variety of shapes than glued wood can. Aluminum is also light, which is another advantage, because it reduces the displacement and results in low fuel consumption. In addition, aluminum shows a high resistance to chafe, has an excellent strength-to-weight ratio, and holds up well under bending stress.

Aluminum oxide forms in a thin coating on the alloy and provides protection against corrosion. Thus, boats constructed of this material can have great longevity.

The disadvantages of aluminum are significant. The cost of aluminum alloys suitable for boatbuilding is very high, and the alloys may be difficult to purchase in small quantities. Although dents may be easily hammered out, punctures may require welding equipment, which is not likely to be available in coastal fishing villages. Moreover, aluminum is far more difficult to weld than steel and requires the high temperatures of arc-welding.

More than 150 aluminum versions of the Alia were constructed in Western Samoa. They have good fuel economy and have proven generally satisfactory, although a few developed cracks.

The characteristics of various boatbuilding materials are summarized in tables 1.1 and 1.2. In table 1.1, materials are compared in terms of their use in construction including cost, availability, skill level needed, building time, and design flexibility. In table 1.2, these same materials are compared for their performance, including strength to weight, fuel consumption, chafe resistance, service life, and ease and cost of maintenance.

TABLE 1.1 Boatbuilding Materials Comparison : Construction

Construction Material	Cost	Availability of Materials	Skill Level	Time to Build	Hull Shape
Logs	1	1	1	2-4	3-6
Bamboo	1	1	1	1	5
Wood planking	2-3	1-6	6	6	1
Strip planking	2	2-6	3	2-3	1
Plywood sheet	2-3	3-6	2-3	2-3	3
Stitch and glue	3-4	8-6	2	2	2
Cold molded	3-4	3	2	2	1
Constant Camber	3-4	3-6	2-3	2-3	3
Fiberglass laminate	3-6	1-6	2	1	1
FRP sandwich core	4-6	1-6	3	2-3	1
Composite laminate	6	1-6	3-6	3	1
C-Flex	3-6	2-6	2	2	1
Aluminum	4-5	1-3	2-4	2-3	2
Steel	1	1-3	2	2-3	2-3
Ferrocement	2	1-2	1-3	2-3	1

Scale:
Cost: 1 = lowest cost
Availability: 1 = readily available
Skill: 1 = lowest level of skill needed
Time: 1 = least time required
Hull: 1 = highest flexibility in design

TABLE 1.2 Boatbuilding Materials Comparison: Performance

Strength-	Hull Weight
Construction	Weight	Fuel	Resistance
Material	Ratio	Consumption	to Chafe	Longevity	Maintenance
Logs	5	5	1	3	--
Bamboo	1	1	3	5	--
Wood planking	4	2	1-3	4	4
Strip planking	2	4	2	1-3	4
Plywood sheet	1	3	4	3	5
Stitch and glue	1-2	2	4	3	5
Cold molded	1-2	2	4	1-3	2-3
Constant Camber	1	2	4	1-3	3
Fiberglass laminate	2	3	2-3	1-2	1-2
FRP sandwich core	1-2	1	3-4	2-3	1-2
Composite laminate 1	1	1-3	1-3	1-2
C-Flex	2-4	3-4	2	1-2	1-2
Aluminum	1	1	1-3	1	1-2
Steel	3	4	1	1-3	2-4
Ferrocement	6	5	2-3	3	2

Scale:
Strength-Weight: 1 = high ratio
Hull weight and Fuel consumption: 1 = low weight and low fuel consumption
Chafe: 1 = highly resistant
Longevity: 1 = long life
Maintenance: 1 = low cost and less difficult to maintain

PROPULSION

New technologies in propulsion include alternative fuels, alternative engines, and unconventional wind-based methods. Alternative fuels include biomass-derived gasoline and diesel-fuel substitutes. Alternative engines include units powered by steam and producer gas. Unusual types of sails and wind-powered rotors complete this section.

Alternative Fuels

Both alcohol (ethanol) and vegetable oils have been examined as potential alternative fuels for small island communities. It was proposed, for example, that it would be possible to produce alcohol from cassava on one of the smaller islands in Fiji. Using a simple fermentation unit and distillation column, ethanol of 95 percent purity could be manufactured and used in modified outboard engines.(National Research Council. Alcohol Fuels: Options for Developing Countries. National Academy Press, Washington, D.C. 1983)

Coconut oil and other vegetable oils have been examined for use in diesel engines. There have been three general approaches in the testing of vegetable oils as diesel substitutes. First, the oils can be used as 100 percent substitutes for diesel oil. In many short-term performance tests, vegetable oils have proved almost equal to diesel fuel. The use of pure vegetable oils in longer term endurance tests has rarely been satisfactory, however. Problems arise with coking and clogging of the injector ports and with fouling of the crankcase oil. Various blends of vegetable oils and diesel oil have also been tested. The use of 80:20 (or higher) blends of diesel oil to vegetable oil has generally proved satisfactory in both short-term and long-term tests. In the Philippines, however, when there was a national program to include 5 percent coconut oil in the diesel fuel, there were significant problems with clogging of fuel filters.

The most promising approach in the use of vegetable oils as diesel fuels involves their chemical transformation. Through the reaction of vegetable oil glycerides with alcohols (such as methanol or ethanol), the original high molecular weight glycerides are converted to methyl or ethyl esters, much closer in molecular size and shape to diesel oil. Performance tests with the esters derived from many vegetable oils have demonstrated good results in both short and long-term testing.

Alternative Engines

Both steam- and producer-gas-powered engines have a special appeal for developing countries, that of fuel diversity. A wide variety of forest and agricultural products and wastes can be used as fuel in these systems. Using coconut-shell-derived charcoal as fuel, producer-gas-powered fishing boats have been tested in the Philippines (National Research Council. Producer Gas: Another Fuel for Motor Transport. National Academy Press, Washington, D.C. 1983) The Intermediate Technology Development Group (ITDG) in London has begun development and testing of a small steam engine specifically for use in developing countries.

Wind Power

Despite the presence of favorable winds in many areas, sailing as a means of propulsion for fishing craft in the developing world has declined in recent years Wind patterns in the tropics are generally stable and predictable; large regions benefit from regular trade winds. In some areas, such as the northeast Indian Ocean, the China Sea, and Malaysia, fishermen continue to use their sailing skills. Large parts of Africa and Central and South America have not developed sail craft because they lack information, suitable materials, or incentive. Retrofitting sails to existing vessels can also be troublesome: hulls may not be suitably designed or sufficiently strong to accommodate masts or the strain imposed by sailing.

Natural or synthetic fabrics are most commonly used for sails. Dacron has proved to be one of the most durable and efficient materials for sails, but for most developing countries, local materials will be more practical and less expensive. Depending on wind strength and sail configuration, a sail area ranging between 1.9 and 6.5 m2 (20-70 ft2) is equivalent to 1.0 hp.

Exploratory research has also been done on hard sails, such as wingsails or airfoils. These can be up to twice as efficient as soft sails per unit area. The best wingsails can provide thrust up to 25-30 degrees from the wind direction. The Cousteau turbosail windship is shown in figure 1.23. This vessel also has diesel engines, which can be used when winds are light.

FIGURE 1.23 The 31-m Cousteau windskip ALCYONE can be powered by its turbosails or its diesel engines or both. (Photo courtesy of the Cousteau Society, a member-supported environmental organization)

Human Power

Arm- and leg-powered devices including oars, paddles, and pedal-driven propellers have all been used for boat propulsion. A highly efficient shell requires about 230 watts (0.3 hp) effective power to attain a speed of 4 m per second (9 mph). Maximum instantaneous human output is about 1,500 watts (2.0 hp), but for a one-hour period, this decreases to about 500 watts (0.67 hp), and for 24 hours to about 370 watts (0.5 hp).

Since humans can probably produce more power by pedaling than any other endeavor, much could be done with pedal-powered propellers. Rowing is a relatively inefficient way to use human power for boat propulsion. Sculling, the use of a rear-mounted oar fixed on a fulcrum, is significantly more efficient.

LIMITATIONS

To gain ready acceptance of fishermen, changes or improvements in boat design and construction should not depart radically from traditional designs. This concern will be automatically satisfied if the local users play an important role in deciding the changes they would like to see in their boats. What works well in one area will not necessarily work well in another.

If new construction materials are used, they must be economical and, if possible, available locally. Local facilities must also exist for the repair and maintenance of the vessels.

Any new design must be appropriate for the fishing gear and methods that are locally used and, at the same time, must enhance the safety of the fishermen.

Before its introduction, a new vessel must first be carefully evaluated and modified as a prototype. Improvements should be recommended and adopted only when it can be clearly proved that they will give the fishermen greater net returns and be economically justifiable.

Improved vessel designs should not be encouraged in those coastal areas that are heavily overfished, unless the new craft can travel farther offshore and tap stocks that are unexploited at that time.

RESEARCH NEEDS

The design of small fishing boats deserves more attention.

Variations of traditional designs need to be tested to determine which give the best fuel and safety performances and are most appropriate for the accepted fishing methods. A series of small, highly efficient hull forms should be compared in single and multihull configurations. These results could suggest innovative vessels that might be easily accepted by local fishermen.

Materials' science has provided new materials that are excellent for boat construction. However, the cost of many of these materials is prohibitive to many fishermen. More emphasis should be given to lower cost, locally produced construction materials. Water-resistant glues manufactured from local materials (lignin, for example) would be an economic alternative to expensive imported epoxy or phenolic resins. Natural fibers might also serve as substitutes for fiberglass.

SELECTED READINGS

Design

Food and Agriculture Organization of the United Nations (FAO). 1984

Manual of Fishing Vessel Design. FAO, Rome, Italy.

Fyson, J. 1986. Design of Small Fishing Vessel Fishing News Books Ltd.

Surrey, U.K.

Reinhart, J. M. 1979. Small Boat Design. ICLARM Conference Proceedings

No. l, ICLARM, Manila, Philippines.

Todd, J., and L. G. Lepiz. 1986. An integrated approach to development of

the small-scale fisheries of the Talamanca coast of Costa Rica. Pp. 187193 in Proceedings of the 37th Annual Gulf and Caribbean Fisheries Institute F. Williams (ed). GCFI, Miami, Florida, USA. Traung, J. O. 1967. Fishing Boats of the World Fishing News Books Ltd.

Surrey, U.K.

Construction

General

Sleight, S. 1985. Modern Boatbuildin, Materials and Methods.

International

Marine Publishing Company, Camden, Maine, USA.

Wood

Steward, R. M. 1980. Boatbuilding Manual. International Marine

Publishing

Company, Camden, Maine, USA.

Harper, E. 1980. Wood Vessel Layup. Institute of Fisheries and Marine

Technologies, St. John's, Newfoundland, Canada.

Plywood

Intermediate Technology Development Group. 1986. South India fishermen helped by introduction of new boats. Intermediate Technology News June:1.

Payson, H. H. 1985. Instant Boats (from plywood). International Marine Publishing Company, Camden, Maine, USA.

Wright, M., and J. Herklots. 1980. Low-cost fishing dories in Sri Lanka: the introduction of 'stitch and glue' technology. Appropriate Technology 7(1):24-27.

Cold-Molding

Brown, J., 1981. Knock on wood part I: plight of the canoe people. Wooden Boat 40:78-86.

Brown, J. 1981. Knock on wood part II: the laminated dugout caper. Wooden Boat 41:50-57.

Chambers, T. 1985. Hot ideas for cold-molded boats. Wooden Boat 63:57-60.

Nicolson, I. 1983. Cold-Moulded and Strip Planked Wood Boatbuilding. International Marine Publishing Company, Camden, Maine, USA.

Ferrocement

Harper, E. 1981. Ferrocement Boatbuilding. Institute of Fisheries and Marine Technology, St. John's, Newfoundland, Canada.

Hartley, R. T., and A. J. Reid. 1973. Hartley's Ferrocement Boat Building, Boughtwood Printing House, Takapuna North, New Zealand.

MacAlister, G. 1980. Ferrocement and the development of small boats. Journal of Ferrocement 10:47-50.

National Academy of Sciences. 1973. Ferrocement Applications in Developing Countries. Washington, D.C., USA.

Sharma, P. C., and V. S. Gopalaratnam. 1980. A Ferrocement Canoe. Asian Institute of Technology, Bangkok, Thailand.

Fiberglass-Reinforced Plastic

de Schutter, J. 1985. Glassfibre reinforced polyester: its application in a boatbuilding project in Lombok, Indonesia. Vraagbaak 13(3):56-62.

Vaitses, A. 1984. Boatbuilding One-Off in Fiberglass International Marine Publishing Company, Camden, Maine, USA.

C-Flex

Kennedy, K. 1977. C-Flex Construction Manual. International Marine Publishing Company, Camden, Maine, USA.

Taylor, M. 1982. C/Flex-fantastic wood sheathing. National Fisherman November 1982.

Propulsion

Asian Development Bank. 1986. Proceedings of the Regional Conference on Sail-Motor Propulsion. ADB, Manila, Philippines.

Asker, G. C. F. 1985. Roller furled genoa and rigid surface wingsail, a flexible, practical wind-assist system for commercial vessels. Journal of Wind Engineering and Industrial Aerodynamics 20:61-81.

Athula, R. 1983. Sri Lanka's experience with sail-assisted fishing boats. In: Proceedings, Intcrnational Confercnce on Sail-Assisted Commercial Fishing Vessels. Florida Sea Grant Technical Report SGR 60, University of Florida, Gainesville, Florida, USA.

Bergeson, L., and C. K. Greenwald. 1985. Sail assist developments 1979-1985. Proceedings, Windtech 85, University of Southampton, Southampton, England. Elsevier, Barking, Essex, U.K.

Blackford, B. L. 1985. Windmill thrusters: theory and experiment. Procecdings, Windtech 85, University of Southampton, Southampton, England. Elsevier, Barking, Essex, U.K.

Callahan, S. 1985. Go sail a kiter High Technology 5(9):61-62.

Fyson, J. F. 1982. Low-energy fishing vessels: the use of sail power. In Appropriate Technology for Alternative Energy Sources in Fisheries, R. G. May, I.R. Smith and D. B. Thomson (eds.). ICLARM, Manila, Philippines.

Fukamachi, T., S. Kabaya, A. Kubota, and Y. Nagami. 1985. Sea Trials of "SAF-27" How Sail and Outboard& Work Together. Yamaha Motor Co., Ltd., Shizuoka-ken, Japan.

Lange, K. 1984. Design and testing of a fishing vessel with combined motor/sail drive for the artisanal small-scale fishery of Sierra Leone. Proceedings, International Conference on the Design, Construction, and Operation of Commercial Fishing Vessels. Florida Sea Grant Report SGR 58, University of Florida, Gainesville, Florida, USA.

MacAlister, R. G. 1985. Application of Sail in Fisheries Development. Report available from MacAlister, Elliot, and Partners Ltd. 56 High Street, Lymington, Hampshire S04 9AH, U.K.

Mitchell, R. M. 1982. The Steam Launch. International Marine Publishing Company, Camden, Maine, USA.

Morisseau, K. C. 1984. Rotor propulsion for the fishing fleet. Proceedings, International Conference on the Design, Construction, and Operation of Commercial Fishing Vessels. Florida Sea Grant Project SGR58. University of Florida, Gainesville, Florida, USA.

National Academy of Sciences. 1980. Alternative Fuels for Maritime Use. National Academy Press, Washington, D.C., USA.

Shortall, J. W. III. 1982. Sailing Fishing Vessels Engineering Economic Analysis. Technical Paper No. 25. Florida Sea Grant Project, University of South Florida, Tampa, Florida, USA.

Shorthall, J. W. III. 1983. Sail-Assisted Commercial Marine Vehicles Bibliography and Abstracts. Technical Paper No. 28. Florida Sea Grant, University of South Florida, Tampa, Florida, USA.

Temple, C. R. H. 1986. Sail power hoists shipping efficiency. Pacific I&land& Monthly. 57(9):27-28.

Thomas, R. 1986. Freighters under sail. Oceans 19(3):45-47.

Torsney, J. 1986. On the winds of change. Lifeline 5(2):88-9.

RESEARCH CONTACTS

Agro-Forest Products Intermediate Technology Associates (AFPITA), P. O. Box 31136, Seattle, WA 98103, USA (B. Bryant)

Asian Development Bank Project Advisor, Jalau Muara 51A, Padang Sumatra, Indonesia (D. Thompson)

Asker Enterprises, The Lincoln Building, Room 411, 60 East 42nd Street, New York, NY 10165, USA (G. C. F. Asker)

pay of Bengal Programme, Post Bag 1054, Madras 600018, India (L. Engvall)

Bundeeforschungsanstalt fur Fischerei, Institut fur Fangtechnik, Palmaille 9, Hamburg 50, Federal Republic of Germany (K. Lange)

Catfish Ltd., Carlton House, Ringwood Road, Woodlands, Southampton S04 2HT, England (E. W. H. Gifford)

Cey-Nor Development Foundation, Ltd., Mattakkuliyaa, Sri Lanka (R. Athula)

Department of Ocean Engineering, Florida Institute of Technology, Melbourne, FL 32901, USA

Fisheries Technology Service, United Nations Food and Agriculture Organization (FAO), Via delle Terme di Caracalla, 00100 Rome, Italy (S. Drew)

Fisheries Division, Department of Primary Industry, P.O. Box 417, Konedobu, Papua New Guinea (D. C. Cook).

Intermediate Technology Development Group, Ltd., Myson House, Railway Terrace, Rugby CV21 3HT, England (B. O'Riordon)

Kamberwood International Services, P.O. Box 550, North, VA 23128, USA (J. Brown)

MacAlister Elliot and Partners, 56 High Street, Lymington, Hampshire S04 9AH, England (R. G. MacAlister)

MacLear and Harris, Inc., 28 West 44th Street, New York, New York 10036 USA (F. R. MacLear)

MIT Center for Fisheries Engineering Research, Room E38-376, 77 Massachusetts Avenue, Cambridge, MA 02139, USA (C. A. Goudey)

Oyvind Gulbrandsen, Myrsvingen 27, 4890 Grimstad, Norway

Sail Assist International Liaison Associates, Inc., 1553 Bayville Street, Norfolk, VA 23503, USA (K. Hill)

Sea Grant Advisory Service, 4646 W. Beach Blvd., Biloxi, MS 39531, USA (C. David)

Seeman Fiberglass, Inc., P. O. Box 13704, 3520 Pine Street, New Orleans, LA 70185, USA (R. Delaune.)

Taiwan Fisheries Research Institute, 199 Ho-lh Rd., Keelung, Taiwan (T. J. Lee)

University of Southampton, Department of Ship Science, Southampton, S09 5NH, England (C. J. Satchwell)

Walker Wingsail Systems, Ltd., Point Hamble, Hampshire, S03 5PG England (John Walker)

Wind Ship Development Corp., P.O. Box 440, Norwell, MA 02061, USA (L. Bergeson)

Yamaha Motor Co., Ltd., 3380-67 Mukojima Arai-cho, Hamana-gun, Shisuoka-ken, 431-03 Japan (T. Fukamachi)

Yee, A. A., 1441 Kapiolani Blvd., Suite 810, Honolulu, HI 96814, USA