The Shambles-

Part of the answer, as was pointed out above, probably lies in the historical fact that for centuries sailors had a share of "prize money" from their capture of enemy merchant ships as well as naval vessels. Soldiers on the other hand had no legal claim to any plunder.

Although the sailors' share of the prize money might appear modest, compared with what the captain or his admiral got, it was still considerably more than their monthly pay and in some cases enough to start a small business ashore.

I also note that the sentiment in the first two verses, collected separately, is radically different and may better represent a cynical parody of the latter verses.

Cheerily,
Charley Noble