I have an older fishfinder and the screen was fogged up pretty bad and made it hard to see what was going on. I had heard that Mother's Aluminum Polish would clear up plexi glass. I gave it a try and sure enough the screen is almost like new. I had to apply and rub about three times but it worked. If the windshield on your boat is fogged up, it will work on it also. I thought some of you guys may want to give it a try.