Not P but Moby-Dick (12)

[Mike Jing]

The following excerpt is from Chapter 36:

Then tossing both arms, with measureless imprecations he shouted out: “Aye,
aye! and I’ll chase him round Good Hope, and round the Horn, and round the
Norway Maelstrom, and round perdition’s flames before I give him up. And
this is what ye have shipped for, men! to chase that white whale on both
sides of land, and over all sides of earth, till he spouts black blood and
rolls fin out. What say ye, men, will ye splice hands on it, now? I think
ye do look brave.”

What exactly does "splice hands" entail here? Does it involve an oath of
some kind, or is it less than that?