I went to my boat today to tie up for any surge from Katrina and found
for the second time that kids have been aboard smoking pot.

I would report this to the police and keep a copy of the report on your
boat.

If you are ever stopped for a search by the USCG and they bring a dog
aboard and find pot remnants, YOU will be the one in trouble and in
danger of losing your boat - UNLESS you have reported the illegal entry
to the police and kept your copy to show the coasties.