It's really not a surprise because that subforum purports to cover a whole lot of specific locations worldwide, yet just doesn't get enough activity to connect very many people from similar regions.
And as you said you're soon going to become something of a seafaring nomad or a "man without a location."
If you want I can give you a few dating site links and local poly group links but again that might not help you given the amount of traveling you'll soon be doing.
Perhaps another approach would be something like:
"As for where to meet poly people, if by some chance you are interested in anything alternative like Renaissance fairs, goth culture, sci-fi conventions, indie music, bdsm, or any small fringe group, you will be more likely to meet people who have at least heard of poly and are accepting of it."
-- SpaceHippieGeek, http://polyamoryonline.org/smf/index...57394#msg57394
If your ship is docked long enough for you to attend a poly event, you could always google "polyamory" with the name of the major city, State, or country you're stationed in. Mostly though, I think you're just going to have to be outgoing, get to know people quickly, and find out soon how they feel about polyamory.
I think your best bet is to follow your instincts and heart. But if you want some of those dating/poly group links, just let me know.