Hello Kmot,
A bit late in the day I know, but the UK laws regarding photography copyright are all-encompassing and they exist to protect the photographer and his or her intellectual property. You as the owner of the model boat photos (with your copyright mark on them) have sole ownership of them and the right to decide how they are used and WHO uses them. The financial penalties for infringements of the copyright are severe. The problem (usually) is proving that an unauthorised person or organisation has used the photos without your permission, and conversely, the offending person or organisation has to prove that they have not used them without seeking your permission first. In your case it seems blatently obvious that your photos have been used without permission, as the copyright/watermark is clear to see on the website where they are located. I would say that it would be worth contacting a solicitor about this.
All the best
Simon ::)