Henry Scheel spent a good deal of time designing pieces of US submarines, so he had a good idea of things that work underwater. Do you think Tartan would have paid a royalty to use the design if it weren't better than anything they could come up with in-house? The drawback to the Tartan 33 that I heard (In Practical Sailor, I believe) were that it needed a good breeze to sail to it's rating because of the fractional
rig.