Via PogoWasRight a link to Coast Guard Boardings and Your Fourth Amendment Rights, Part 1. According to the author, the 4th Amendment has no traction at sea: the Coast Guard can board US flag ships at will, whether on the seas, on rivers, or in port, without the least suspicion.
Sorry, but when it comes to Coast Guard boardings, you don’t have any rights.
I’m surprised how many boaters don’t know this. The US Coast Guard can board your boat any time they want, and look anywhere they want, without probable cause or a warrant. They can do this on the open sea, or while you’re asleep aboard in your marina at midnight. They can look through your bedsheets, in your lockers, in your bilges, in your jewelry box, or in your pockets. They can do it carrying just their sidearms, or they can do it carrying assault rifles. They can be polite about it or they can be rude, but mostly they’re polite.
The article does not say, but I presume this even applies to houseboats?
Yes, it would apply to houseboats – if they are within CG jurisdiction.
I suspect if you loooked at the law on this you would find that it is akin to the Fourth Amendment law regarding the TSA at airports. Someone reasoned that the CG has an “important job to do” and therefore they are allowed leniency in this regard.
Not that I agree at all, but that’s more than likely what’s at play.