On last sat i did races (small mono's) and the skipper had a very nice compass mounted. We (he) started to work out the wind angles/mark settings before the race...

we never once used the compass during the 2 heats we ran (1st and 2nd) before we broke the boat! I think it would have been a distraction, but if we couldnt see the marks i bet it would have been great!

ever since we had a fog fest in Dunedin during the Hangover Regatta 2 years ago (and we had about 15 boats without the ability to see, or even really guess where land was..) i carry a small $2.00 compass with me..