Not quite sure, wheather you can link it to a mac - but if you want something reliable with no problems of working after getting a shower (which it might get when operating offshore) I would buy
https://buy.garmin.com/shop/shop.do?cID=156&pID=6426#
But only, if my old Garmin GPS 90 stops working - which is fairly unlikely ;-)
Greetings Flying Bull
