Many thanks for the reply CB90 👍
I believe the original Fairey CSB was single hull.
I have indeed thought of creating my own plans (or rather a CAD model), but I really need access to a boat. Does anyone know of anyone who owns a CSB on the central south coast of England and could put me in touch please?
There is a Fairey Owners Club with a website and forum, but as the name suggests I believe one has to own a Fairey boat to gain access (please correct me if I'm wrong).