It's funny that you suggested that. I'm having the same discussion over at my boating site and I threw out the idea of a cookpot or a metal dome to shield the cradle assembly.
After poking around the 'net I'm surprised that there isn't more discussion about this. Lots of small-boaters out there and many of them are quite techy what with their marine electronics such as sonar, gps, ais, etc.
Hopefully others will share their ideas/solutions here at 'Geeks.
Whatever
I learn I'll report back here.