Where did you or where would you mount a GPS unit? Is it easily accessible from the helm?
I put mine on a swing mount (Ram) so that I could get it out of the way when not in use. Works well, I can get by it into the companionway when I need to. Because it stays inside most of the time, it is not deteriorating at all. The downside is if you get into heavy weather and want to put both drop boards in you cant see it. I've toyed with the idea making up another drop board with a lexan panel in it to see the unit in those conditions.
(http://i1007.photobucket.com/albums/af200/brackish_photos/Arionmaidenvoyage001.jpg)
I'd forget that GPS, and just head toward the Champagne.
If anyone is looking around, West Marine has the Garmin 441s on sale for $299. This is a very good deal. I just picked up one of these units and I had one on my previous boat. I paid well over $100 more for the unit a few years ago when I bought it. There is a limited supply as they are an older unit that they won't make anymore.
Pretty much the same setup as Brackish on Serenity.
(https://farm9.staticflickr.com/8460/8066902669_6e2fc90593_s.jpg) (https://flic.kr/p/dhQZ7M)Untitled (https://flic.kr/p/dhQZ7M) by Compac23 (https://www.flickr.com/people//), on Flickr
Shawn