Prepping the hull for painting

Kelpie

Kelpie

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I'll shortly be rolling up my sleeves to do a major repaint of the topsides.
I read somewhere about Abranet sanding mesh (other brands available) which sounds brilliant stuff, especially where bulk removal of antifoul is required. I don't anticipate removing all of the antifoul, but as I am adding a boot top line I will at least need to remove the old eroding AF from that area.
The discs are sold in packs of either ten or 50... can anybody comment on how many I should expect to need, and what grits? It's supposed to last much longer than normal sanding discs.

I'll be taking most of the existing paint off and then applying undercoat and topcoat, so I'm guessing something fairly coarse (80?) initially, then something to smooth off the filler (120?) and then something to flatten off the undercoat (240? Or smoother?). I don't know if I'll end up sanding between topcoats, presumably depends on time and weather, but I guess that would need something like 320 grit.

As well as sanding, I wonder if I should be using any sort of degreaser, and/or tack cloths? The boat isn't undercover so most of the dust ought to blow away.
 
I'm afraid it's a very difficult question to answer - how many discs you'll get through. So I won't comment on that due to the many variables.
What I will suggest is that Abranet discs are designed to be used with an extraction system, where the waste product is secured rather than being left to "blow away".

This may sound off and I don't mean to single you out, I only mean to highlight the potential problems.

Please consider extraction.....

This can be as simple as hooking up the sander to a Henry hoover.

Despite the dust being blown away, it has to be blown somewhere. The concern is it will be blown away to where others are breathing. I don't want to breath in a product that is designed to inhibit growth. Think about it...

The Abranet discs have an amazing ability to keep going where others get clogged, but you will only see this beneifit with an extraction system of some sort.

Tony
 
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Tony

Wise words.

I won't use insecticides and herbicides for the same reason as I notice the distinct changes to my environment over the last 30 years.

Meta-analyses have reported higher than average levels of various cancers among farmers and pesticide applicators. These include non-Hodgkin lymphoma, leukaemia, multiple myeloma, brain cancer, prostate cancer, lip cancer and skin cancer.(Wiki)

Clive
 
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Kelpie said:
I'll shortly be rolling up my sleeves to do a major repaint of the topsides.
I read somewhere about Abranet sanding mesh (other brands available) which sounds brilliant stuff, especially where bulk removal of antifoul is required. I don't anticipate removing all of the antifoul, but as I am adding a boot top line I will at least need to remove the old eroding AF from that area.
The discs are sold in packs of either ten or 50... can anybody comment on how many I should expect to need, and what grits? It's supposed to last much longer than normal sanding discs.

I'll be taking most of the existing paint off and then applying undercoat and topcoat, so I'm guessing something fairly coarse (80?) initially, then something to smooth off the filler (120?) and then something to flatten off the undercoat (240? Or smoother?). I don't know if I'll end up sanding between topcoats, presumably depends on time and weather, but I guess that would need something like 320 grit.

As well as sanding, I wonder if I should be using any sort of degreaser, and/or tack cloths? The boat isn't undercover so most of the dust ought to blow away.
Click to expand...
 
Hi Kelpie, I'd be interested to hear about your experiences in preping and painting your hull. I've just started on the same task. Some of the antifoul just flakes off, right down to the gel coat, but mostly its as stubborn as hell to remove.
My topsides paint I've also decided has all got to come off. In places mostly near the waterline it has completely delaminated and blistered away from the hull. Some blisters contain the oily looking blister juice associated with osmosis, however other blisters appear dry underneath and gelcoat seems ok.
What method of removing antifoul and enamel/ topsides paint worked best for you? I'm looking at buying a powerful pressure washer and attachment for lance to blast with combination of abrasive media/ water.
Sofar my efforts with hand scraper and polesander/sanding mesh over several days have removed only maybe 10% of hull surface, I've got time on my hands at moment being furloughed but honestly loosing the will to go on as i have.
 
Removing Antifouling. I first started using Nitromors Paint Stripper in the early 1960's and being familiar with the product I would use it in the early 1970's to remove Antifouling, which in those days was TBT which is now known to be totally unsuitable for small boats but they are allowed to use it on supertankers.
The way I do it works for me, I brush a strip of paint stripper about 12" long and 4" wide. and immediately scrape it off with a paint stripper. This takes it back to the Gel Coat, but with smears of stripper still on the gel coat, I get some kitchen roll, splash a bit of thinners on it and wipe the gel coat. This leaves the hull perfectly clear. OK it takes a bit of time to do a hull, but for me its better than using an orbital sander and wearing a mask.
Perhaps considered dangerous today , especially if you smoke but this is what we did in the 1970's
 
Hi Jim@sea, I'm wondering how many tins of stripper you used.. and what size was your boat?
I must have about 9-10 coats of antifoul to remove on my 50yr old Nic26. I may try paint stripper if the pressure washer water/sand blast combination does'nt work.
 
Jim@sea said:
Removing Antifouling. I first started using Nitromors Paint Stripper in the early 1960's and being familiar with the product I would use it in the early 1970's to remove Antifouling, which in those days was TBT which is now known to be totally unsuitable for small boats but they are allowed to use it on supertankers.
The way I do it works for me, I brush a strip of paint stripper about 12" long and 4" wide. and immediately scrape it off with a paint stripper. This takes it back to the Gel Coat, but with smears of stripper still on the gel coat, I get some kitchen roll, splash a bit of thinners on it and wipe the gel coat. This leaves the hull perfectly clear. OK it takes a bit of time to do a hull, but for me its better than using an orbital sander and wearing a mask.
Perhaps considered dangerous today , especially if you smoke but this is what we did in the 1970's
Click to expand...
Unfortunately, Nitromors is no longer the Nitromors it was. Elfin Safety means we aren't allowed to use anything that works now.
 
I bought some methyl chloride based paint stripper off eBay. It came with warnings about “professional use only” and “use correct PPE”. I tried it on the rudder, where it did remove the antifoul but also softened the underlying gel coat, to the extent that I was concerned that it would damage it permanentl. So I stopped using it and washed the area down with water. Resorted to using scrapers to remove the remainder of what was probably 30 or 40 years worth of paint. Only a small boat but it took us a about 4 hours per side of the hull.
 
I had tried all antifoul removal gels and liquids and found them useless if the paint is thick or heavy layered , sanding was the only thing that cut through it , and it took days , you will spend hundreds of antifoul removal liquid
Although that was 42 ft hull .
Pads abranet, but how many really depends on thickness, and if its soft and clogs up, a good heavy duty sander is essential I used a bosh Professional sander with variable speeds , and in really thick places I had to use a grinder to take it down but need to be very carefully
40 grit , then 80 , then 120 I never sanded between coats ,
 
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