... with his crew on the Saucy Jack.
T is instructed to meet someone "with a monstrous visage and a feather in their cap. They'll carry a silver shook and wear their heart, but not on their sleeve" with the letter. Captain Lucas Geliefden is mentioned in the SoT RPG book, as well as the SoT RPG voyage book "Juliana's Heart". Captain Lucas has a hook (that could be silver) and a hat with two feathers on it (is two too much?). Geliefden is Dutch for 'loved ones'.
I'm just saying, he fits the letter's profile. That's my theory and I'm sticking to it.
(I am also possibly incredibly wrong but there ya go.)