The mini cargo ferry was designed in response to a need to replace the outboard powered fibreglass skiffs which are ubiquitous in the Pacific. These boats are expensive to run, difficult to maintain and have almost completely destroyed the islanders boat building and sailing skills. The Islands are also at the forefront of efforts to reduce global warming so there is a lot of interest in low cost (capital, operating and ongoing), locally built, low/no emission alternatives.
The table below gives an idea of what is required. The Priority number indicates the importance of each. Boats are ranked 1-5 (5 being good) on each requirement and the 2 numbers multiplied together and added up. The maximum score possible is 605. The mini cargo ferry scored 569.
To achieve this score, a different approach was required. Instead of breaking new ground with radical ideas, we had to take conventional ideas and make them fit. This was particularly evident with the requirement that the boats had to be built by local, unskilled people using minimal tools and easily available materials. In fact, the build and sailing had to be so easy that once someone had built a boat, they could be expected to sail it home and teach their fellow villagers how to do it. Given that a conventional boat building apprenticeship is several years, this was a big ask.
The hull shapes are box section with straight sheer and rocker. The dimensions are based around sheet ply. The bottoms, cockpits and decks are half a sheet wide. The sides are 2/3 sheet high. The windward hull is 3 sheets long, the lee hull is 4 sheets and the cockpits 1 sheet. There is one curve for the deck and bottom at the ends. This is drawn with a bent piece of stringer, cut and used as the master curve for the other 7 cuts. The result is not pretty, but it can be built with no setting up, levelling or measuring and no tools beyond a hand saw and some sandpaper, plus a small table saw if the timber and ply is not bought cut to size. The stringers are triangular so that they are easily glassed and sealed. The ply sheets are butt joined together, then the joint is glassed on both sides. The stringers are glued in place on the deck and bottom, bulkheads cut to length from one of the half width sheets of ply and glued in place. The sides are then bent around and glued. The edges are rounded and the exterior glassed.
There are no screws (by far the main cause of rot in plywood/epoxy boats), everything is clamped with sand bags or spring clamps made from offcuts of pvc tube.
All surfaces are glassed, skim coated to ensure sufficient thickness of epoxy and painted to protect them from the sun.. All up weight is about 500 kgs/1,100 lbs.
The beams are also timber/ply/glass/epoxy, the deck is slatted timber and the spars, leeboard and paddle are wood/glass/epoxy because that is what is available locally. Longer term, the skill level may be increased to include PET recycled foam and Intelligent Infusion for a lighter, cheaper, rot proof option. This will be even easier to build than the ply boats, but needs a bit more infrastructure.
Pacific Islanders know more about paddle steering and lateen sails than anyone else in the world, so that is what we chose. I am really looking forward to learning how these work in the hands of experts. Because of the shallow hull, we included a simple, tied on bidirectional leeboard to improve upwind performance, particularly when the boat is unloaded.
It is possible that for some routes, upwind performance will need to be emphasised. In this case, an unstayed rig with tied on sails may be a better option. If so, a mast step can be added to the floor and the beams used to support the mast atdeck level.
The boat has a capacity of 1,000 kgs/1 ton which can be people and/or freight. The cockpits (1 sheet of ply long) are deep and self draining with seating along the edge. They are large enough for a cooler for fish or other fresh goods.
The deck is slatted timber to make it easy to move around on and store stuff on.
The beam clearance is high but still allows easy boarding/alighting for passengers, loading cargo and landing fish. The masts for the schooner rig are stepped on the beams near the hull and stayed to the ends of the boat. If a single sail is required, a third beam can be added to step the mast on.
An option is to include a small steering cockpit aft so the helmsman is not perched on the deck.
The situation at the end of March 2019
The organisation that prepared the ‘List of Requirements” table has short listed the mini cargo ferry for building and testing in the Marshall Islands in late 2019. Rob will be visiting to show how it is built and sailed. It will then be compared with the other 2 short listed boats. The successful craft will then be part of a build program which has the potential to spread across the Marshalls, the Pacific and the World, aided by the generous budget allotted to the process.