“You may think personal sub owners are the last thing on the mind of intelligence agencies and governments”
I can’t comment on the Patriot Act as it doesn’t affect me but I would like you to consider how may clandestine uses there are for Boats, Aircraft and other vehicles and human mules without the need for submarines. There are more drugs and contraband than we could imagine moving around the world every day using these modes of transport and there not banned.
Again the example you use is a sub being built by an organised and recognised extreme group not an enthusiast or private owner. Besides if you want to smuggle drugs into a country there are simpler ways. For example fill a few large sized oxygen cylinders (with the valve intact) with your chosen substance and weld them to the hull or in the bilge of a tanker or container ship below the water line.
When I was diving commercially one job I had for a while was to inspect the hulls of vessels coming into Port Kembla and Port Botany from the Golden Triangle for this sort of thing. You would be amazed what we found.
There are bigger global dangers out there but if they ever ban personal aircraft for reasons of national security I agree subs will be on the list. They are more likely to insist on special licences and new rules one day because a few clowns start bumping into other watercraft.
If this happens Bill you may well consider becoming a lobbyist and push for self regulation.