protocols on copying someones work

While perhaps its sounds "unfair" the sketcher of the boat that you posted has taken the basic EXISTING boat lines and just mixed them around to create a new shape.

As shown in Post 11, he has plagiarized/copied/stolen (perhaps unintentionally) the shape of rear opening salon doors, the forward slanting window along with the cabin shape features as well as the raised fore deck. I could see major issues then that if he had design/copyright protection on his sketch, and he decided to defend/ legally challenge any boat that has any precise shape or even general shape close to this sketch, and if he was successful, (ie if the laws of the country agreed with him) would then EXISTING companies (with similar shapes) have to enter into some type of royalty agreement with him?

If this person's ancestors had painted the Mona Lisa, basically a picture of a women sitting on a chair, would then could they have had copyright protection for any other picture of a women in a chair?

 

Legally I'd guess you are A-OK to 'copy' a semi-fuzzy drawing painting as far as making a real object or even set of hard line blue prints. Patent office does have "design patents" but those are all accurate hard line drawings.
Morally, IMO you'd be a nice guy to mention his drawing as among the things that inspired your product.

 

Having designed a number of marathon racing canoes over the years and seen competitor's boats develop amazingly similar shapes underwater, I've taken the position that imitation is the sincerest form of flattery.