My observation on the subject.
If you use fireshot before grappling the boat, it will likely sink instead of giving you the chance to grapple/board. Once you grapple the ship, I dont think any amount of cannon fire will sink it. You must board a flagship to receive its plunder. When/if they sink prior to being grappled/boarded, plunder is not rewarded, generally your only reward when that happens, is the "reps" earned.
Zeppers lvl40
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