Tips for wet sanding gelcoat

Discussion in 'Boat Yard Basics' started by hferrell87, Jul 14, 2014.

  1. hferrell87

    hferrell87 Well-Known Member

    Hey all,

    I have done a bit of research and am about to wet sand the underside of the hull from the keel to the transom. I have read through many different forums and have seen many different opinions of what grit to use.

    A little about what I am working with. The hull is in great condition, but has the normal rash on the bottom from kissing the sand a time or two... :'( Also have a couple larger scratches from previous owner getting oyster rash.

    I have the equipment to buff with wax and the time to wet sand by hand.

    Should I start with 800 grit, followed by 1000 grit, then apply wax?

    I appreciate any help and look forward seeing what works best from people that have first hand experience!
  2. Mooseknuckle

    Mooseknuckle I Love!

    Youre missing about 4 steps in between 1000 grit and wax. Sand down to 1500, then to 2000, then start buffing with a 300 grit compound on a wool pad, then 500 on a polishing pad, then we can wax.

  3. DuckNut

    DuckNut Brandon, FL

    Watch closely when you are sanding or you could sand right through - easy to do especially on edges.
  4. CurtisWright

    CurtisWright Light, Strong, Cheap. Pick Two.

    What everyone said but Get a DA Sander, start with 600 then 1000 then 1500 and maybe 2000. Then begin the polish.

    It will take you a day to do with a DA sander. You may never finish by hand.
  5. el9surf

    el9surf Well-Known Member

    Save yourself the time and take it to Jonathan Glasser. He will take care of everything including the deep scratches. When you pick your boat up from him the gel coat will look brand new.
  6. jasonrl23

    jasonrl23 Plays with Glass...

    Heres the process I used for building plugs prior to molding. And it depends on the level of orange peel or scratches youre trying to eliminate.

    Assuming you have nothing similar to orange peel. You can easily knock down most deep scratches with 400 grit paper. Then move on to 600, 800, and 1000. Always keep a small stream of running water while sanding.

    The key is between grits clean the area thoroughly. Clean your orbital sander. You want to remove ALL excess grit from the larger sized paper.

    Rarely do you need anything beyond 1000 grit paper if you have the right polish. Aquabuff is all Id ever use.

    A variable speed orbital grinder with a buffing pad + a spray bottle to keep the surface wet at all times = awesomeness

    And again it comes down to keeping the buffing pad super clean. Wash it consistently during the buffing process.

    Never had mold that didnt have a mirror finish using this process.