I just wanted to put this here to remind me of it in the future as a possible useful tool: Garmin GTU 10 GPS Tracking Unit It seems quite small so would fit in/on most ships. It's more expensive than the Mini Global GPS Tracker with GPRS I bought already, which I haven't tried yet, but it is a Garmin and I'd expect it to work very well. Plus the battery life is very long. Still, I should probably give my cheaper device a try first as they both use similar technology, and there is no subscription with the cheap one.
Just found this also: http://dx.com/p/mini-multi-functional-gsm-personal-position-tracker-for-child-elder-black-250295 Possibly the same thing in another box?
I meant the one in the second link on the first post, not the Garmin. Having said that, it still does look a bit different.