Hyne, Cutcliffe: Honor of Thieves (1895); v.1., 21 Jun 2019
 

A roving adventurer discovers an unmapped navigable channel which leads deep into the Florida everglades, and then finds a dubious ship owner who devises an clever insurance swindle. Load half a million British gold soveriegns, ostensibly for export to gold-hungry USA; sail it into the secret channel; and have it vanish, credibly lost in the Gulf of Mexico. Claim on the insurance; keep the gold.

Then they hire a down on his luck skipper, one Owen Kettle, as Captain, to carry it out.

What could possibly go wrong?

The first appearance of Captain Kettle, but not as the main character in this debut.

Essentially a "caper" novel. Text source Internet Archive.