Bottom Paint Questions

[wildsteelheader]

I own a 2120 that has NEVER been bottom painted before and I am looking for info to do it myself. I have never painted a boat bottom before and was looking for some general knowledge. Didn't know if anyone might have a write-up or video, so far this is what I have found and any help or tips would be greatly appreciated.
I was told to tape it off above the high water mark. Sand the bottom to an egg shell white, basically remove the gel coat.
Apply 2 coats of Interlux primer followed by 2 coats of Trinidad bottom paint.

Does this sounds correct?

Will a general Dewalt pad sander work or do I need to purchase a more powerful sander? What type grit sand paper do I need? Can I use one grit or does it take a 2 step process to prep for primer?

One other question I had was to use a roller or brush to apply the primer and Trinidad?

Any help or tips would be appreciated.

 

[TWOBOATER]

You've got the basics. Unless you have a good scum line showing on the boat, I would launch the boat and mark the waterline from a dock or a dinghy with a wax crayon every two feet or so and each corner (bow, stern quarters). Mask a uniform distance up from your marks. De-wax the hull with Plex (wax and silicone remover) or acetone and clean rags at least three times, turning the rags often. Now, Sand (don't remove) the gelcoat with 80-100 grit to a nice uniform haze. A DA sander makes this go pretty quickly. De-wax the hull once more with solvent. Apply two coats of Interlux 2000-2001 epoxy primer and follow with a good hard bottom paint. Trinidad is good. Check the application "window" for bottom paint on the primer label to avoid having to sand the primer before applying bottom paint. I use a hard (non-ablative) bottom paint on a new bottom because it won't wear through to your primer from cleaning the first year. Next year you can go right over it with a multi-season ablative if you want. DO IT RIGHT THE FIRST TIME, Don't skimp on the de-waxing and sanding or the paint will fail and you'll have to start all over again. Do it right and your bottom will look good for years to come with minimal maintenance.

 

[DaleH]

NO, you are NOT removing, nor trying to remove the gelcoat. Before you sand, you need a bunch of rags and a ton of elbow grease and solvent wash (wear heavy rubber gloves) the hull in 2'+ sq-foot areas with Acetone, working only 1-way down the hull. Do not put a dirty rag to a cleaned area. Swap rags often.

You are trying to fully remove the mold release that is on the hull that allowed it to be popped from the mold. Once clean - sand - then lightly solvent wash again.

Some like to add an epoxy-based bottom primer, but it is an expense that really isn't needed. I would paint 2-coats of a red or blue bottom coat with an inexpensive, hard epoxy anti-fouling (buy West Marine brand, comes from Pettitt), then the final top-coat of the ablative of your choice ... just make sure the hard base coats are a different color than final topcoat.

Then if/when you see 'red or blue' you know the ablative is thin in that area!

 

[TWOBOATER]

I strongly recommend an epoxy primer coat. it sticks like nothin' else and also takes bottom paint better than plain gelcoat.

 

[DaleH]

I strongly recommend an epoxy primer coat. it sticks like nothin' else and also takes bottom paint better than plain gelcoat.

Its certainly an option. If one does that, you could skip the 'other' color hard epoxy AF coat and go right to your ablative of choice.

 

[Megabyte]

When my bottom was completely re-done, I did both a light grey epoxy primer, then a first coat in "Grady Blue".
My topcoat now is Pettit Hydrocoat in black.
Once I start seeing areas of blue showing through, I know that it is time to re-paint.

 

[wildsteelheader]

Thanks guys appreciate it! I feel good about starting this task. I have just a few more questions.

I'm going to apply 2 coats of the interlux 2000 primer, Any idea of how much product I should purchase to complete the job on a 2120?

The second thing I want to clarify is that I will only apply ONE coat of Trinidad after the 2 coats of interlux, Not TWO coats right?

I'm assuming if I apply only one coat of Trinidad, 1 gallon should be enough to finish the job?

Thanks again, you guys rock!

 

[TWOBOATER]

It's probably best to get two one-quart kits of the primer, as it is two-part product and your doing two coats. Two quarts of bottom paint should do yah as well. Use the newer smaller diameter 6" rollers with 1/4" nap. They will suck up a lot less of your expensive paints, and leave a nice finish. The second coat of both products will take less to cover than the first coat.