There are actually two issues here: 1) Copying your image without giving credit and 2) linking directly to the image on your site. There's not much that can be done about 1). A person with rudimentary editing skills can remove the watermark, and I'm not convinced the club is harmed by eBayers and others copying images. The buyer maybe, but not the MOGH. 2) is much more harmful, since linking can increase traffic to the MOGH server. I watermark my images because I figure I at least get some advertising from improper linking.

You might want to consider a compromise - put your watermark under the chip. It's easier to remove in cases of 1), but still lets people know the source for 2).