31′ Ply Catamaran – DVD#058

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As a yacht designer, I am often asked a double-barrelled question ie. “Do you have your own boat and, if so, what type is it? The answer to the first part of the question is “not at the moment” but if it were yes then the answer to the second part is shown on this page. Does a two part question need two hulls in the answer? Of course it does!! I believe that this simple catamaran will be ideally suited to those with small budgets, wanting an exciting boat to cruise locally and race occasionally.

For my cruising area, which is the NE coast of New Zealand’s North Island, this will be a great boat to visit the myriads of islands and bays which abound from the Bay of Plenty in the south to the Bay of Islands further north. The philosophy of this little cat is that she will be simple to build and maintain, will be devoid of complicated and costly systems, will offer “camping” style accommodation for up to six people and will offer exciting passages from one location to the next. More “bang for your buck” if you will!
As is evident from the drawings this design is still at the concept stage because “designer’s never seem to have the time to work on their own project’s, right?” In contrast to our specialisation in the field of metal boats, this cat will be built from plywood and epoxy, with filleted and taped joints and seams. Those wanting to “splash out” can sheath the entire hull in cloth but this won’t be essential. A good coating of two-part polyurethane over the epoxy resin will suffice.

Central to the theme of this boat is the absence of any athwartships bridgedeck structure. Less volume to be sure, but this results in less overall weight and keeps it simple (& less costly) to build. At this point I am envisaging large diameter alloy tubes as crossbeams which are simply lashed to built-in strongpoints on the hulls. I reckon that come winter I’ll just beach the boat at high tide, demount the beams and trailer her home where she can be cleaned & stowed away, ready for next year’s adventures.
Powering will be via a 20-25 hp outboard, bracket mounted under the aft main crossbeam. The rig is simple as can be with three stays only, rotating ply/epoxy wingmast. I’ve shown a trampoline in the bow but this can be omitted if the budget is tight. The asymmetrical spinnaker could be optional unless some racing is envisaged. Not shown but also possible (and necessary for racing) would be retractable daggerboards instead of the stubby fixed keels.

Let me know if this boat is as appealing to you as it is to me and we’ll see what can be done about getting the design back on to the drawing board and detailed for construction!

View the plan

Principal Characteristics:
LOA - 9.50 m (31’ 2”)
DWL - 9.11 m (29’ 10”)
Beam Overall - 5.69 m (18’ 8”)
Beam (Hull) - 1302 mm (4’ 3”)
Draught 600mm - (6’ 10”)
Sail Area - 49.5 m² (533 sq. feet)
Power - 20-25Hp Outboard
Displacement - 2250 Kg (4960 lbs)
Hull Material - Epoxy-saturated Marine Plywood