Not sure if water is getting in or just never has a chance to dry out. In Whittier we get about 133 rainy days producing about 185 inches per year. It only gets above 60° F a month or two and then just barely above. Usually in the 40° F range so when it is not raining it is cloudy and doesn't really get a chance to dry things out very well. That is why I was thinking of replacing with a tube type structure which sits on sacrificial spacers which would permit good drainage and could be replaced periodically when corrosion set in. I really like your idea. I was just brainstorming how to prevent it happening again. Of course it has lasted since 2004 so not a real issue. Some day it would be nice if someone would build a boat that could get wet.