Handmade Submarine From Revolutionary War Found In NY Harbor

The gentleman sitting on top of the bulbous-shaped submarine is an artist, and not some sort of professor or war nut. So I wonder, what drove an artist, one Mr. Duke Riley, to build a functional submarine?

Apparently it was constructed of mostly basic material of plywood, fiberglass, and lead (isn't that stuff dangerous?). The picture also shows the police quite irritated in discovering that the gentleman inside is in fact not a terrorist trying to blow up the Queen Mary II.

My only question is, why are the police suddenly concerned, when judging by the gunk on the side of the little sub, this isn't the first time its been out? I will give them that it does look like it could be a large buoyant bomb, but why on earth would someone target a cruise ship?

Fiberglass Ghetto Sub Intercepted in Brooklyn Harbor Missing Pastrami, Cheddar, Pickles [via Gizmodo]