transtamp

noun:
An artistic decal, or painting, on the transom of a boat.

a portmanteau of 'transom' & 'stamp' and a homage to the classic 'trampstamp'.

~bcoe

The very back of a boat is called a transom. On most boats this is where boat-name decals would go. On some boat a more artistic approach is used and images are placed there.

that is a transtamp.