Yacht Drawings

For several years now, I have been drawing colored pencil drawings of the megayachts (generally around 100-150 feet--not so "mega" for this forum, but nevertheless) when I am on vacation with my family. I have given many of them to the crews of these yachts, and they're generally pleased.

I am trying, however, to start a small business (a few hours a week perhaps) selling these drawings to yacht owners and/or crews, and I'm wondering if anyone has advice on what would be a good way to get started. I've printed up some postcards, but I've not gotten any response from the marinas where I left them. Any ideas?

PS I can upload copies of some the pictures if anyone's interested in seeing them.