I sent POTCO an e-mail about Undead Captains,and here is what they said.
"Thank you for your recent message.
Undead Captains are the strongest creatures in Jolly Roger's skeleton
army and, as such, do not tend to lollygag about the islands. The only
place you will find an Undead Captain is at the helm of a high level
skeleton ship. Keep a weather-eye towards the shores of wild islands
like Isla Cangrejos, Isla Perdida, and Outcast Isle as higher level
ships tend to haunt those locations. Just remember that seeing an Undead
Captain is a rare event, but walking away to tell about it is even
rarer, so make sure to level up and bring a crew! "
Not lying!
