Royal Marines and the Parachute Regiment's exercise rivalry

What prank did Royal Marines play on the Parachute Regiment during exercises?

An anecdote describes painting the Parachute Regiment's name under boats so it would be visible if one capsized.

The story describes an unofficial practice of putting the Parachute Regiment's name on the underside of Royal Marines boats. A capsize would then appear to implicate the rival unit. The anecdote is treated as harmless exercise rivalry. Other practical jokes are mentioned, but no specific retaliation for this boat prank is established.