Just an idea, there's a model boat plans group on Facebook (I'm told) where old plans are shared, including requests. It might be worth a shot.
If your search fails, get together whatever dimensions, drawings, pictures you can and post again here. It's likely that an existing plan or model could be rebuilt to look like the old one, and you will probably get some suggestions for a starting point. A lot depends on your modelling experience, but it wont be too difficult.
Charles