3M Marine High Strength Repair Filler, 46013, 1 qt

Amazing stuff. Strong smell but easy to work with. Amazingly hard when dry- and yes- very difficult to sand. Because of this, I missed that you don't want to build this product up too high (because it won't sand down without some real power sanding), and use the 3M Premium Marine Filler for shaping/ smoothing/ sanding the surface (fairing). I bet the two of these would make a nice combination, although you could probably stick to just using the Premium Filler and not this "high strength" product for scratches and repairs that don't need the inherit strength and hardness of this "High Strength Repair Filler."I'm not sure how far this product will go to successfully repair "semi-structural" issues. For instance, how much of a crack in a hull will this product repair before you really need the traditional fiberglass sheets/ epoxy approach. I do know this product seems amazingly strong and has fiberglass itself in it. I will see how my repair holds up over time.

Easy to use, but beware it sets very fast. Easy to sand final shape. Withstands immersion very well.

Sticks well, and cures rock hard. This is vinylester based filler, so it's just what I needed for below the water line repairs in my boat. And if you add a small amount of vinylester resin to thin it a bit you can get a really nice finish that feathers pretty decent.

I had to patch a proper hole in a boat, color didn't matter as it was being covered. Easy to work with, but once it's set, it is SET. Super strong.

Worked great. Setup fast....definitely need to follow the direction to keep it below finish level and put sandable filler over it. This stuff is super hard. Had to use a grinder to knock down some high spots.

Superb adhesion compared to polyester filling putties. Rapid cure,

Works great for filling voids in a fiberglass car body. I used this to fill holes and other imperfections in a fiberglass car body. It was easy to mix, spread, and sand. I had never done any bodywork before and this gave me great results.

Works great. Just be sure you tape off areas well. This stuff is just as tough as the surrounding fiberglass if not tougher. So if you aren't careful you can create more work for yourself on the Sanding end.

Fast delivery option worked great