Question on First time bottom paint - need help

[SeaRaySD220]

Hello all,

I have been told two different ways to bottom paint a boat for the FIRST time.

1) Primer and then paint

2) No Primer, but sanding it down and then just paint.

Which is better for a salt water environment and will have best results to fight growth and barnicles.

My boat will be sitting in a salt water environment in a slip for 7 months out of the season.

 

[The Great Escape II]

Re: Question on First time bottom paint - need help

I would recommend a barrier coat 1st and then 2 coats of bottom paint. They are for 2 specific purposes: The barrier coat helps protect the fiberglass from blisters and helps the bottom paint adhere. The bottom paint protects from marine growth. I would also suggest walking the docks and ask what some boaters are using specifically in our area. Bottom paints work differently some better some worst depending on the water. There are a lot of good brands, Petits, Interlux etc..

 

[slasmith1]

Re: Question on First time bottom paint - need help

1) clean with solvent
2) sand
3) barrier coat
4) 2 coats high quality bottom paint

If the boat will be stored on a trailer for any length of time I recommend a hard paint if it will spend all of its time in the water use an ablative paint.

 

[arks]

Re: Question on First time bottom paint - need help

I have been told two different ways to bottom paint a boat for the FIRST time.

Depends on the hull material. Fiberglass and aluminium have different requirements.

1) Primer and then paint.

This is for aluminium hulls.

2) No Primer, but sanding it down and then just paint.

This is common with fiberglass hulls. Some Notes:
- Before sanding you need to de-wax the hull.
- Only sand enough to 'knock down' the gloss so the paint will adhere.
- I agree that a (10 mil) barrier coat should be applied after sanding and before application of the antifouling paint.

 

[Home Cookin']

Re: Question on First time bottom paint - need help

Great suggestion to ask around your area as to what works. Even saltwater environs differ if you are closer to the ocean or on a tidal river. Also consider whether you can or will haul the boat out during the 7 months to maintain the paint: easy for a 17' not for a 37'.

There are lots of methods including a chemical that acts like sanding. The web sites for the name brand paints have a lot of information, but it gets confusing after a while--just don't mix steps 1&2 with one method with steps B & C for another.

Some paints do not work if they are removed from the water for any length of time and so you'd need to repaint every season (and I recall that is the hard paint, not the ablative, contrary to another post, but I could be wrong). I have had good success with micron (ablative) on a fiberglass boat I keep moored for 6 months and on the trailer for the rest, and use all but 2 months out of the year. I can just squeeze three years out of a paint job, but I wash the bottom during the summer once or twice.

You will use a different paint and primer/undercoat for your metal parts: bottom of the lower unit and motor bracket; trim tabs; through-hulls; swim ladder support; transponders. Follow those directions. (For some reason, my metal parts' paint failed completely even though we followed all instructions--it's like it just washed off. Will trouble shoot next season).

 

[Chris1956]

Re: Question on First time bottom paint - need help

if the boat has never been painted before, no matter how old it is, you need to make sure all the wax is off of it. Use some wax removal solvent.

A lot of manufacturers use vinylester resin on the exterior part of the hull (gelcoat), to add waterproofing. You obviously do not want to sand thru this layer.

There is primer that you may use that does not require sanding. However, I recommend epoxy barrier coat, instead of plain primer. Follow directions carefully as overcoating is based upon temperature. Use two or three coats, depending on the directions. Some products want 5+ coats, BTW. I like to avoid them.

Now use an ablative antifouling paint suitable for the climate of your dock. Two coats are enough for two seasons. Prepare to touch up the paint each spring, and scrub it gently each fall.

 

[The Great Escape II]

Re: Question on First time bottom paint - need help

Another suggestion is to use a different color for your barrier coat say light grey and a darker color like black for your bottom paint. This will show you that it's time to repaint when the light grey is showing.