Stuck on Captain Dennison/Gentry quest

[Peggo]

I'm having trouble with that guy(s) too. I tried boarding too.

[Pirate Rose]

The last few days we haven't had to board to capture. Have you tried sinking a high level frigate? For some reason, sinking sloops doesn't work for some of these tasks.

[Davy]

I usually sink Greyhounds for my Navy quests. And also, I think Captain Dennison is Commander Gentry. Captain Dennison Gentry at your service. He is a captain of a ship, and is the commander of a part of the Navy force. After the pop-up reminding you that you captured him comes, then go to an island that doesn't have a teleport option, Like Isla Perdida, Isla Tormenta, Driftwood Isle, to name a few. A wild island is an island that does not have a teleport option.