Re: Storage of firearms on board
You are subject to state laws of all kinds whenever you are in a state, and that includes the traditional 3-mile boundary out from its shores. And of course you are subject to federal laws at all times in US waters, at least up to the 3-mile line.
Firearms, bestiality, gambling, alcohol...all the same.
LEOs ask about guns (or sometimes "weapons") basically because a "traffic stop" is the most dangerous part of the job. They don't know who you are, and they're afraid of getting shot. Yes, it is that simple, and if you've taken a driving safety course in the last 30 years they pretty much all tell you that if you are pulled over, put both hands on the steering wheel so they are in plain sight. Because whoever comes up to your window is nervous, is afraid you might shoot them, and might do something premature like, ah, panic and shoot you first.
Of course, if you don't answer the question, they'll get even more nervous. You could always respond "Why? Are you looking to buy, or do you just need assistance?" And as we say "This vessel follows United States Navy protocols, so I can neither confirm nor deny the presence of any nuclear weapons on board this vessel."
Guns. That should be the least of their worries.