Tell that to the Marines!
That is a saying meaning “I don’t believe you!” It was used by Sir Walter Scott in Redgauntlet:
Tell that to the Marines, the sailors won’t believe it.
(Brewer was of assistance here.)
Yo-ho-ho, and a bottle of rum
is a frequent refrain in Robert Louis Stevenson’s Treasure Island (which is available for free download for the Kindle).
Hang from the yard-arm.
The yard-arm is part of the upper structure of a sailing ship from which miscreants were hanged. There are oblique references to this use in Treasure Island.
In the crows’ nest means very high up. The crows’ nest is a basket high up on the main mast where watch can be kept. I mentioned keeping a weather eye out here.
Come through with flying colours is an expression about great success. Colours are flags used for sending messages at sea.
Tarred with the same brush means having the same defects of character. A tar-brush was used to make boats waterproof.
Spring a leak is a description of the beginning of water flowing in through the hull of a boat. On land a stream begins from a spring. The boards of a boat might spring apart.
Ship of the desert is a camel. It is used for transport there.
Keel over means fall or collapse. The keel of a boat is the lowest part.
Up to the gunwales (or gunnels, which is the pronunciation of both spellings) means full. The gunwales are the tops of the sides of small boats. In olden days the guns would be sited there. (Concise Oxford Dictionary)
Jesus was in a boat with more water than his disciples would have liked. The story is told in Matthew 8:23-27