It was accepted for a submarine.

But... that's not a boat. Shouldn't it be Subby McSubface?

It's the remotely controlled support vehicle.

Remotey Remoteface?

Droney McDroneface?

Subs are boats.

They're subnautical vehicles. They're beneath that.

The German name, "Unterseeboat", and the English adaptation, "U-boat" both imply that they are a type of boat.

I'm starting to suspect some dark humour here. But it runs silent, runs deep. And seems to have gotten all wet.

Well I guess in that instance Boaty McFloaty was automatically disqualified.

Careful now, that's humor, and we frown upon that around these parts. D:

Boaty mcdouble?