I would not buy him something that was decorative only (aka useless!) - space is at a premium on a boat (very limited for displaying "nice" things and even for storage)......and for me an antique style Compass
would fit into that, especially as not an original! Will live in storage
onboard at best........
I would also hesitate to get him anything useful without first checking as he may either not want the item or already have better (at least to him).
Given that the budget
is fairly decent (IRO $500? rather than 50 bucks and a card!) if you can't wheedle the info out of him then I would straight up ask for a couple of options, including a sextant
- and E-bay for s/h is a good (and acceptable) option.