Copyright applies to drawings and other printed matter. If you create your own drawings, you may be able to make copies of the drawings without infringing on the copyright. You can not make copies of the offsets. Unfortunately for designers, the design is not protected, just the drawings.

In the end the primary protection a designer has is ethics. And that depends on the individual making the copies. If you are taking someone's design and modifiying it you will need to decide for yourself whether you are creating a new design or just a modification of someone elses.

If the modification is slight, such as simple scaling, it is hard to say you've changed the design at all. If you start actually changing curves, but are keeping the general shape of the base design, then you should at very least give credit to the original design (but take the blame for any deficiencies in the design :-). If you make wholesale changes to the design and spend a lot of intellectual effort on it, then the design is yours.

By this I don't mean to imply you should fell free to xerox any set of lines you like and spend a lot of thought to on making a something new and different and never pay a thing. If you like the base design well enough use it as the starting point of something new, you should be so kind as to give the original designer full credit. I.e. buy the design.

A rhetorical question: If you feel you know enough about designing a boat that you can modify an existing design, why don't you just create a new design from blank paper? If you are doing it because you are not confident enough to start from scratch, or you just want to save time, then you are making substantial use of the original designer's efforts, and probably owe him a fair amount of credit.

Personally, I would rather someone create a new design from scratch (owing me nothing) than have them buy my plans and then mess them up. I'd rather have all the credit/blame for a boat that is purely my design, than some of the blame/credit for a design that is only partially mine.

> My thoughts exactly. I'm surprised that it amtters whether I
> use the tiny picture or the offsets though. I have access to a CAD
> system, so putting in offsets is no big deal, it just takes a little
> longer than a Xerox machine. The only drawback is that I kinda like
> the hull shape of the Guillemot Play (Below the waterline).

> I had even though of putting offsets of a couple of boats into
> a spreadsheet and having it interpolate a mean curve between the two
> (at each station).

> As you might have guessed, working up the lines is part of the
> fun for me. I've even thought of using the offsets for Nick's stitch
> and glue boat in a spreadsheet, and using a little curve smoothing
> to round the chines a little.

> What if I blow up the lines from study drawings for several boats
> on a Xerox machine, superimpose them onto one sheet, and use them
> as a guide to do my own shape, and then destroy all of the xerox copies?
> I could just look at several tiny pictures and try to mimmick them,
> but it'd be easier to have them together on a fullsize sheet.

> Would it be ethical to build from plans, and then, instead of
> throwing out the forms, cut them into a new shape (add a little here,
> shave a little there) and call it my own design?

> I find these design rights discussions very stimulating.