They’re pointing out that aircraft carriers are heavy as fuck and float just fine.
Fair enough.
I guess I assumed that people were thinking of electric-battery powered boats based on the discussion. But if its just a matter of weight, we all know that boats can be arbitrarily heavy and still float (as long as they are big enough to compensate for that weight).
No electric, though. If it had electric, it would be too heavy. And if there was a shark 10 feet away? Not a chance.