Hull Scraping

[twistedline]

Hello all,

I'm very new to all this so be gentle.

I started scraping the old anti-foul paint from the hull and i'm not sure sure what I am looking at underneath.

The red paint comes off easily but leaves another coat of paint which may be a primer? There are also patches where the second coat has come off and there's a rough texture, i'm not quite sure what this could be.

I would appreciate input from anyone with experience. I am also interested in how much I should sand/scrape before I put new paint on.

Its a 1984 Hunter 25.5.

Here's some pictures.

 

[Roy10289]

Perhaps hull was sand blasted at one time and they went through the gel coat in these rough areas? I also see 2 blisters several inches to the left of the rough area in your picture. As far as scraping,anything that is adhered enough to be difficult te remove can probably be left on. However if those rough areas are into glass matt (throufg gel coat), I would soda blast the bottom,repair those areas as well as any blisters,and apply a barrier coat to seal everything before bottom painting again.
I know it's more money and work now,however in my opinion,trying to just paint over this problem will only come back to bite you harder next year.

 

[s sauer]

Scraping Bottom Paint

You would be able to use a Red Devil paint scraper ( hardware store variety) to remove most bottom paint by hand and be able to gauge if you want to or need to remove everything. You could hand scrape the entire bottom and then use 80 grit sandpaper to smooth any rough edges and provide "tooth" for the barrier or primer coat to adhere. Check with your marina to see if you can do dry scraping and hand sanding over drop cloths for disposal. The rough texture 'white' you are seeing appears to be gel coat that the previous owner may have aggressively sandblasted. You can infill and fair out those rough areas with Marinetex applied with a drywall spatula and sanded even when hardened. Use at lleast three coats of Interlux 2000 as a barrier coat.
Soda Blasting to bare gel coat may not be warranted unless you have extensive blister problems needing drying out and filling. I hand scraped a 28.5 years ago to remove a type of bottom paint that was no longer manufactured and to be able to add several coats of Interlux 2000 as a barrier coat; then changed to the new bottom paint.

 

[twistedline]

Thanks for the information guys.

I am already using something similar the red devil scraper and was planning to use 80 grit to finish. I have been putting off scraping the hull so only did a little bit to see how hard it was, I will check with the yard owner but I was using a large tarp to collect all the scrapings.

Blasting would likely cost more than a paid for the boat so not my favorite option. I already have some Marinetex and plenty of two part epoxy so will most likely and do as you say and patch any rough areas, at least for this year. I will clean the rest of the anti-foul and see what other gremlins I can find.

Would you put three coats of Interlux 2000 on the entire hull or just the patched areas?

Thanks for your help.

 

[Ed Schenck]

To me the rough area looks like barrier-coat. The light gray appears to be paint so that you would know when the red was too thin or gone. But I have never seen a barrier-coat that rough. You need to scrape through a small spot to see how deep you have to go for smooth gelcoat.

I recently had my boat soda-blasted. Not sure if the picture shows it but the barrier-coat is much rougher than when first applied. I am wondering how much "smoothing" I should do before bottom painting this spring.

 

[Tom L]

Hi Twistedline, I think Brian (owner at the marina) will tell you to catch what you scrape off with a tarp and use a vacuum sander when sanding. Check with him to be sure but this is about what he told me. I bet he would be willing to take a quick look at the spot on your boat and give you his opinion about what it is. he seems to know what he is talking about.

Nice boat, thanks for showing it to me the other weekend. Tom L.

 

[twistedline]

Hi Twistedline, I think Brian (owner at the marina) will tell you to catch what you scrape off with a tarp and use a vacuum sander when sanding. Check with him to be sure but this is about what he told me. I bet he would be willing to take a quick look at the spot on your boat and give you his opinion about what it is. he seems to know what he is talking about.

Nice boat, thanks for showing it to me the other weekend. Tom L.

Hey Tom,

I will talk to Brian next time I see him, but he never seems to be around recently, actually I hardly ever see anyone. I'm sure that will all chance soon once the weather improves.

Cheers,

Warren.

 

[MLampner]

Twisted line if you are at the MD Marina Brian is normally in only week days this time of year. Generally he is more than willing to help and if you call him he'll go look and get back with you by phone. Martin the taller heavy set man is generally there on the weekends and also knows his stuff.

 

[Crazy Dave Condon]

Over the years, I have seen several ways to remove paints and coatings. From the orginal picture posted, it could have been sand blasted at one time and to be blunt, that is the worst thing to do. You have to fill the holes up with two part expoxy which can be expensive and labor consuming or sanding down to a smoother surface with many barrier coatings to be applied. I am not sure about soda blasting but it is said to be less severe than sand blasting.

One thing many people tend to forget, a fiberglass hull will retain moisture and the hull has to be dry when applying any barrier coats of any kind. There are moisture meters but the old method other than tapping the hull for the sound is placing a piece of plastic taped all around the edges and then check to see if there is any moisture on the inside the following day. It usally takes about 6 weeks to dry in warm weather and longer during winter months for a hull to dry.

crazy dave condon

 

[BillyK]

looks like damaged gelcoat. if thats what it is, sand around to get a nice border, brush it to get all the loose out of it and then fill it with 2 part epoxy filler using a large putty knife, sand, barrier coat, ablative.

i'm going through this exact same process right now. i'm on the barrier coat step now..

 

[twistedline]

looks like damaged gelcoat. if thats what it is, sand around to get a nice border, brush it to get all the loose out of it and then fill it with 2 part epoxy filler using a large putty knife, sand, barrier coat, ablative.

i'm going through this exact same process right now. i'm on the barrier coat step now..

Hi, just to follow up, it was indeed the gelcoat they must have left the sand(soda?)blaster on that spot for too long. I sanded that spot with 80 grit and it smoothed out nicely, I will go finer and then then put several coats of Interlux 2000 on it. I finished scraping one side of the boat and didn't find any other problems.

Its hard work but still better than joining a gym.