A while ago i remember that alot of members were having their boats stolen and whilst watching the Gadget Show on channel 5 ,in the uk, they were testing this security marker that would show up under uv light,ah whats new i hear you say but this stuff has a unique combination of chemicals almost like a fingerprint that youegister the number on the bottle and when it’s found the poice scan the boat with this light ,match the code and bingo you have you boat back .I’m sorry but i cant remember who made it but i guess there is a website some where or even go thru the gadget show website.