TackTracker

You TackTracker can be mounted anywhere on your boat or carried on your person.  The important factors are it is not shielded from getting a good satellite signal and it stays dry.  On the subject of shielding, I have had good success with the GPS inside a bouyancy tank, but this is likely to reduce the strength of the signal.

If you don't travel fore and aft a great deal you may carry it in your pocket, if you have one and as long as it can't fall out.  To keep it dry, you need a waterproof pouch, even if you have a water resistant model GPS.