: First, if you are making a kayak for your personal use, copyrights
: are not being violated. A copyright is a means for preventing
: another party from profiting from one's work. No sale - no
: profit. That said it still is a reasonable courtesy to ask the
: original designer.

Intent to profit is NOT a criteria for infringement in many jurisdictions, including the U.S. For example, copying music for personal use (pirating) can be illegal.

Similarly, patent infringment has no profit motive criteria in the U.S.

The following Wikipedia articles give a good summary of U.S. law in layman's terms:

http://en.wikipedia.org/wiki/Patent_infringement
http://en.wikipedia.org/wiki/Copyright_infringement