Copyright 2017 - Woods Designs, Foss Quay, Millbrook, Torpoint, Cornwall, PL10 1EN, UK
  • home built Flica 37

  • plywood Romany 34

  • lightweight 14ft Zeta mainhull

  • Strike 15 trimaran at speed

  • 28ft Skoota in British Columbia

  • 10ft 2 sheet ply Duo dinghy

  • 24ft Strider sailing fast

  • 36ft Mirage open deck catamaran

When we first started drawing strip plank boats, back in the early 1980's, we drew and built them using a "male" mould. Ie we set up frames that looked like upside down bulkheads, and then strip planked over them. So the frames are set up in exactly the same way as one would do when building a conventional stringer frame or foam sandwich boat.

This way has the advantage that it looks like a boat so is easy to fair and it takes up the minimum of space. The disadvantage is that after releasing and turning over the hull is relatively floppy until the inner glass skin has been laid up. Also it is not possible to add furniture or bulkheads before glassing the inner skin.

These disadvantages have led many people to use the "female" mould system. This means the boat is built "insideout". Instead of having "bulkhead shaped" frames the frames look like the bit of plywood you'd normally discard. The advantages are that you're working on the inner side of the hull skin, so you glass the inner skin first. It also means you can add bulkheads etc before releasing from the frames. The disadvantages are that more space is needed. What you're building doesn't look like a boat while it is in the frames, so it is potentially harder to fair. There has to be a join down the centreline which is hard to make especially at the bows - possibly the most important part of the boat to make strong.

As far as I am concerned, the jury is still out, so at present I will continue to draw boats built with the male mould system until I'm convinced otherwise. However, whichever way the boat is built, the final result will be the same. There is no difference in strength or weight between the two systems, it's only the way the boat is built that is an issue.

NOTE: The same arguments apply to the two similar systems for building foam sandwich boats as well.

When I first started drawing strip plank cedar boats good quality western red cedar was readily available. Now it isn't, which means it can be very expensive. Fortunately it is possible to build the strip plank cedar boats using double diagonal plywood instead. The Merlin uses 2 layers of 3mm (1/8th in); larger boats use two layers of 4mm (3/16th in).

It is probably best to build the hard chine ply versions of Wizard and Sango rather than try to cold mould their hulls as they are very curved and using two layers of plywood will be tricky to do. The disadvantage of the cold moulded stringer/frame system is that you have the stringers and frames inside, rather than a clean interior. However there is probably a weight saving over strip cedar, especially on the smaller boats.