You can use it direct but do not let it run down the vinyl or gelcoat without immediately wiping up. Use a medium stiffness brush to work it in and get the grit out. Also keep it off of the britework (aluminum, stainless). I pull the cushions and do them outside the boat and cover stuff inside to keep it where i want it. It sounds like a pain but it's easy. Make sure to condition with a UV protectant afterwards.