I do a lot of professional development with teachers around integrating technology into teaching. Copyright, proper citation of web-based products and fair use are huge issues.
Many people erroneously believe that if it is on the Internet, it is in the public domain, and they simply do not understand that it is wrong to copy. I also would say it is a cultural thing - our society copies CDs, records tv programs, and often makes "copies" for personal use. Once that copied information is disseminated (sold, published, even given away), copyright is violated. These well-meaning folks probably put the photo on their website because they enjoy it so much and it brings back fond memories of their cruise they want to share, and don't realize that they have violated copyright by doing so.
On a personal note, when my own children complete school projects using web-based text and photos, my kids are now in the habit of copying and pasting the URL in order to show the source of information as well as the date retrieved - proper citation.
The right click java script is one good idea. I haven't visited your site yet, so I don't know if you have a statement on your website regarding persmission (or lack thereof) to use photos and a procedure for contacting you. Do you have information on your website to sell you photos? If folks like them that much, make them affordable and sell in digital and/or print format.
You have every right to protect your copyright on your work.
I look forward to visiting your website and seeing your photos!