My local marine supplier is going out if business and every thing is 40 % off so I bought some of this 3m filler and it seems to be a good product that is easy to work with. Not as cheap as mixing your own but very convenient for fixing spots here and there when you don't want to mix a bunch. Apply easy and spreads well, not as good as a glaze but it is still fairly smooth and it sands very very easily. I like that it is vinyl ester based so it resist water absorbsion and since I use ve resin it is chemically compatible with it too.

I used it on my trailer a couple years ago with no problems.... Although I rarely leave my trailer in the water. :)