Bottom painting - general questions

[capslock118]

Bottom Painting:

Quick questions about bottom painting:

when buying paint, does it need to be shaken like paint at a hardware store?
take a look at the pictures below:
--though the boat was powerwashed last year, i take it I should scrape the left overs before painting?
--take a look at the bottom of the hull, does this look fine enough to paint over or do you think it needs glass?

 

[Chris1956]

Re: Bottom painting - general questions

I thin the glass is OK. Try to get the remains of the barnacles off.

Antifouling paint must be throughly mixed. Use a mixer device that chucks into your drill to get all the heavy copper into suspension. use masking tape to tape the top of the paint line. This gives a clean edge. Pull the tape off before the paint dries. Wear gloves as heavy copper is not great for injestion via skin contact.

 

[Fireman431]

Re: Bottom painting - general questions

Prior to painting:

Pressure Wash
Sand almost down to gelcoat
Wash, clean, and wipe down with prep-sol
Roll on paint

A quality bottom paint job should last 5-8 years, not 18 months as some people say.

 

[Chris1956]

Re: Bottom painting - general questions

Fireman, I must disagree. Quality paint jobs look great for years, possible the 5-8 years you cite. However, the effectiveness of the antifouling coating diminishes over time. I get two years out of a paint job, and then the barnicles start to win the battle.

 

[Hank496]

Re: Bottom painting - general questions

It looks like you have an ablative paint. So all you need to do is scuff up the surface and then roll on a new coat. I also think you can remove the rust colored stains above the water line with an acid based hull wash. If you want to do that, do it before painting the bottom, it will dissolve the bottom paint. Just mask the existing bottom paint to prevent the hull cleaner from softening the bottom paint and marking the area above the waterline.

 

[adam7]

Re: Bottom painting - general questions

How much should it cost to touch up some bottom paint? I bought my boat with the bottom paint on there but I don't know how old it is. I was thinking I could just touch up the few areas where it has worn off from scrapes and beaching. It doesn't stay in the water now, but I was thinking of getting a slip for a few months this summer.

 

[capslock118]

Re: Bottom painting - general questions

It looks like you have an ablative paint. So all you need to do is scuff up the surface and then roll on a new coat.

hmm, i'll probably end up scuffing the surface in order to get rid of the barnicle remains. I was planning on applying a primer that will ensure the old paint and new paint are compatible.

How much should it cost to touch up some bottom paint? I bought my boat with the bottom paint on there but I don't know how old it is. I was thinking I could just touch up the few areas where it has worn off from scrapes and beaching. It doesn't stay in the water now, but I was thinking of getting a slip for a few months this summer.

I plan on buying a gallon for my boat - I think I am overestimating by saying my boat will take 19'x10' (190 sq. ft) as my boat is reall 19'x8' or maybe less on the beam. The lowest price I found in my parts was about $110 a gallon and covers 400 sq. ft..

Anyways, I did touch up last year and the year before the prior owner touched up and the year before that he did the entire bottom. This past fall there was buckets and buckets full of barnicals on the boat.

I wouldn't recommend touching up - i'd paint the whole thing like I will be if you plan on keeping the boat in the water all season.

 

[Hank496]

Re: Bottom painting - general questions

To apply a primer you may have to go all the way to gelcoat. That means a soda blast, or many long days sanding by hand. If you think you need to start over just because there a barnacles, you are mistaken. Barnacles are there because the chemicals in the bottom paint were too weak. If the existing paint is on solidly over most of the clean it up and just over coat. Again using an ablative. You can tell by rubbing a rag on the surface. If you get a blue chalky smear on the rag it is ablative.

You are off on your formula, it is LOA x beam x 0.85 (doing the numbers my self for my boat as I type). That comes out to 130 sq ft for you. Interlux micron CSC has a spec coverage of 440 sq ft per gallon. You might be better off just buying quarts. I think you'd only need two, but buy three and return the unopened can if you don't use it.

 

[Fireman431]

Re: Bottom painting - general questions

Fireman, I must disagree. Quality paint jobs look great for years, possible the 5-8 years you cite. However, the effectiveness of the antifouling coating diminishes over time. I get two years out of a paint job, and then the barnicles start to win the battle.

That's generally the result of poor prep and improper coatings. A quality (that's the key here) bottom job, which can take up to a week, depending on the size of the boat, if done right. This is based on proper prep and adequate coats/complete coverage of a quality product. That means taking ALL of the old paint off, fairing out the bottom, priming, and 2-3 coats of ablative coatings.

I use Trinidad Pro ablative paint on my boat. The bottom job on my boat was done in late 2005, and sits in salt water 1/2 the year and in tannic water the other 1/2. No barnacles, no growth, ever. I'll probably be due for another redo next year (which I'm not looking forward to).

Based on what a lot of people are saying to do (scuff & paint), that is why they get paint adhesion blisters and have to repaint in 2 years.

 

[capslock118]

Re: Bottom painting - general questions

To apply a primer you may have to go all the way to gelcoat.

Interesting, I read that I would use a primer if I didn't know what type of bottom paint I have on my boat (I don't), i'm not removing the old paint (i'm not) and I wanted to paint over the old paint.

Based on what a lot of people are saying to do (scuff & paint), that is why they get paint adhesion blisters and have to repaint in 2 years.

Another interesting point. Not sure If I would strip the bottom this year, it's not in my budget and I am not sure I am willing to take sand the whole boat while it's sitting on a trailer; maybe some day.

 

[Fireman431]

Re: Bottom painting - general questions

Go to the Pettit website and read their info pages. It's at the top of the page asking about bottom paints. There are multiples ways to adequately prep the boat for painting, depending on the water you're in, the use of the boat, the formulation of paint you are going to use, and the prep work you're willing to do.

http://www.pettitpaint.com/

 

[Chris1956]

Re: Bottom painting - general questions

Fireman, I wouls suspect the success you see is due to the lack of marine growth in the water, not your paint job, sorry. 2 coats of ablative paint simoply doesn't last 5-8 years, in normal salt water environments. Maybe the artic or brackish water...


No primer can be used over A-F paint. If the existing paint is well stuck to the hull, and is hard A-F paint (most anything but the real soft copper paint), just paint over it.

Caplock, If you want to strip to gelcoat, after you have all the paint off, I would recommend at least 3 coats of epoxy barrior coat, then 2 coats Ablative A-F Paint.

 

[Yacht Dr.]

Re: Bottom painting - general questions

Bottom Painting:

Quick questions about bottom painting:

when buying paint, does it need to be shaken like paint at a hardware store?
take a look at the pictures below:
--though the boat was powerwashed last year, i take it I should scrape the left overs before painting?
--take a look at the bottom of the hull, does this look fine enough to paint over or do you think it needs glass?

Yes it is preferred to shake your BP. Drill stirring will not only make a mess if your not carefull..but will " bubble/airate " the paint. If you do drill stirr..then let is set for 30 mins. Then after that put the lid on and give it a few shakes.

You should allways scrape and feather loose paint off..

You dont need glass . You should remove those calcium barnicle deposites off there prior to your BP.

As far as primer goes..what BP are you thinking about ? I just had to buy some BP from Pet** ..our cost was $350/gal !!

I like the Interlu* CSC micro* ... more better is VC-17 . .. .. mebbe after you strip ..

YD.

 

[capslock118]

Re: Bottom painting - general questions

As far as primer goes..what BP are you thinking about ? I just had to buy some BP from Pet** ..our cost was $350/gal !!

I like the Interlu* CSC micro* ... more better is VC-17 . .. .. mebbe after you strip ..

My budget is tight this year (when isnt it?) and I was just looking at the West Marine CPP Plus Antifouling Paint; it's not bottom barrel price but it is $110 / gallon.

 

[Chris1956]

Re: Bottom painting - general questions

I have used the West marine CPP stuff before. It works fine. You should get two years out of two coats. I used a small (~1-1/2") foam roller this year. I did 2 coats on my 21 footer, with 1/2 gal of AF paint. I think the small foam roller wastes a lot less pain than the normal paint rollers.

 

[Yacht Dr.]

Re: Bottom painting - general questions

Ive never used the WM ccp ..

I like the VC-17 though top notch and not that expensive ( 50 bucks a qt or so .. ) but it goes on like water.

When I was talking about ( a few posts up ) this Petti* stuff at 350 a gallon.. I laughed. I asked the if the owner realized he is going to buy $800.00 in paint ! Not to mention labor cost..they said um.. dunno..this is what he asked for. I think thats absolutely friggin mad myself !

YD.