Construction Questions

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Q Can I use local timbers in place of the timbers specified in the design?
Q Can I use 3mm plywood in place of laminate veneers?
A Usually – Yes.

For laminated frames which are generally made from 3mm veneers, 3mm plywood is a reasonable substitute. Perhaps not quite as strong as frames made from true laminates, but certainly strong enough.

And for the diagonal veneers for the second and third skin on a cold-moulded hull, 3mm plywood is also very acceptable. In fact because the ply veneers cross each other at 90º, two layers of 3mm ply veneers at +45º and -45º will give you six layers of diagonal veneer (assuming the ply is 3-ply). So, in theory, this is stronger than real laminates.

Not all plywood types are manufactured in 3mm. Occumé plywood is however often made in 3mm and would be very suitable. As ever with plywood, make sure to get a reliable ply, from a manufacturer and supplier that you trust. There is a lot of rubbish ply out there in the market, often stamped "Marine" or BS 1088" when it is no such thing.

Remember BS 1088 is a British Standard for Marine plywood. It is a very good standard and genuine BS 1088 ply will be very good. But the standard is only enforceable in the UK. So ply manufactured elsewhere (often loosely called "Far Eastern") can have a BS 1088 stamp on quite inferior plywood, with impunity.

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Q Is it possible to substitute ply "sandwich" frames (like Design 152) for conventional laminated frames?
Q I've noticed that ply lapstrake is often thinner than a cold-moulded hull skin. Why is that?