tie1on,
You can get an inexpensive game camera. If they don't steal it too, you might get good photos or video of the suspects, but LEO would have to recognize them to match the suspect. The camera idea has been used again and again on anhydrous tanks, meth labs at remotte locations, marijuana grows, store fronts and so on BUT they seldom do much to stop theft or help with solving the crime. If you could get a license plate number or in this case boat number it might help.
Even the kids that break windows and take stuff out of cars (called car hopping) call it a "Stupid Tax." According to the criminals, the owners were stupid to leave it in the car even if it was their own driveway.
The onus is on the crooks not the honest guy, but the honest guy that doesn't learn is going to keep being taxed so to speak.
To throw another idea out there....motion sensor lights have been proven to thwart the criminals a bit as they don't like light.
I don't want to steer this toward political but the looters in Joplin and the stuff that occurred during Katrina were a pretty sad show of how we treat each other in the worst of times. I am not sure if it was true but the Tsunami in Japan didn't seem to have looters. If that is in fact true I wonder why the difference.