Sanding antifouling...

[Iain C]

My boat is currently out of the water in a yard, and rather than my usual hurried "between tides" antifouling effort, I have this weekend to do something a bit better.

She's a 32' fin keeler, usually a/f'd in self polishing, however after many years she is a bit rough and dimpled in places and I'd like to give her a light sanding just to smooth her off a bit. She's probably go faster and be less inclined to foul in the first place.

Obviously I want to do it as safely and considerately as possible. I've heard people talking about using some kind of sander on a pole with a hose pipe to keep the dust down...can anyone tell me what this device is? What grit paper should I use?

Also, in terms of PPE, what is the correct mask to use?

Finally, if doing this is going to turn into a marathon back breaking session, I probably won't bother, but if it's easily do-able in a day with the right kit and I'm going to see a noticeable difference in hull smoothness, it is something I'd do. So any experiences are very much welcomed!

 

[pvb]

It's not going to be an easy job! Eroding antifoul is fairly soft when it's wet, so wet sanding is the optimum way, and of course it stops the dust. I use a running hose and one of those little coarse-grade foam sanding pads, it seems to remove the worst, but it's a filthy job. As there's no dust, I don't wear a mask.

 

[lw395]

Wet sand it.
However if the boat has been out for many weeks the AF may have gone brittle and tend to flake off easily when scraped.
I have tried all sorts of ways to keep the area of work wet, an old towel hanging from the toe rail is the simplest.
A bit of fairy liquid in the water seems to reduce clogging?
Something to stand on is preferable to a pole sander IMHO.

 

[Iain C]

Thanks for the replies. Turns out the device in question is a drywall sander, which plugs into a hoover and keeps the bulk of the dust down. Anyone got any experience of one of these? Could be a good, quick, clean solution?

 

[wiggy]

What you wand is a pole sander https://www.screwfix.com/p/pole-san...MIx6u9soiC5AIVy7HtCh2V7ghtEAQYASABEgKgw_D_BwE and course sanding screen https://www.amazon.co.uk/3M-Drywall-Fine-Grit-4-19-Inch-11-25-Inch/dp/B00004Z4AI

 

[Bobc]

What you wand is a pole sander https://www.screwfix.com/p/pole-san...MIx6u9soiC5AIVy7HtCh2V7ghtEAQYASABEgKgw_D_BwE and course sanding screen https://www.amazon.co.uk/3M-Drywall-Fine-Grit-4-19-Inch-11-25-Inch/dp/B00004Z4AI

I think what he needs is his head tested personally.

 

[pvb]

Thanks for the replies. Turns out the device in question is a drywall sander, which plugs into a hoover and keeps the bulk of the dust down. Anyone got any experience of one of these? Could be a good, quick, clean solution?

I wouldn't dry sand antifouling in any circumstances.

 

[Baggywrinkle]

I did my 36ft AWB myself ... once. Never again. It was a filthy job which took me a week in total and every evening I looked like Papa Smurf and turned the shower water blue - that was despite disposable overalls, gloves, masks etc. It took weeks for the residue to wash off completely. It was also hard physical work - I did have a thick build-up of old antifouling that was flaking off in big chunks, leaving a very uneven bottom.

By the time you've bought all the bits and pieces, protective gear, consumables etc. you don't have to spend a massive amount more to get it professionally stripped.

Masking up and re-painting was the easy bit.

 

[[70521]]

I stripped back my old boat by hand. NEVER EVER again...

 

[Pye_End]

Something like this:
https://www.toolstation.com/prodec-advance-sanding-mesh-115mm-x-5m/p41259

or courser

on https://www.toolstation.com/prep-hand-sander/p55929 (or one on a pole)

and a spray head on a hose in the other hand.

Wet antifoul as much as possible. Put hose in one hand and mesh in the other - that way you can keep the mesh reasonable clear of paint. You probably only need to change the mesh a couple of times for the whole boat - much better than wet and dry.

 

[Graham376]

Easiest way is to scrape with a 2 handed tungsten carbide blade which doesn't create much fine dust, followed by light dry sanding with random orbit sander with good dust extraction. Plenty of shop vacs around with good suction and HEPA filter - ordinary vacs won't collect the very fine dangerous particulates.

 

[wiggy]

100% agree, I taped the hose to the pole sander to keep everything wet, the only problem was the constant dribble up my arms, no dust and with a course mesh and some brute force it doesn’t take long to make a considerable impact on the surface.

 

[ithet]

What you wand is a pole sander https://www.screwfix.com/p/pole-san...MIx6u9soiC5AIVy7HtCh2V7ghtEAQYASABEgKgw_D_BwE and course sanding screen https://www.amazon.co.uk/3M-Drywall-Fine-Grit-4-19-Inch-11-25-Inch/dp/B00004Z4AI

Cheaper at toolstation,
need https://www.toolstation.com/pole/p50469
and https://www.toolstation.com/swivel-sander-head/p12186

But I found their 120 grit sanding mesh too fine for areas with a lot of layering. Got better results from 60 grit sanding mesh (from ebay etc.).

In use, I wet an area of hull with hose, then use mesh, rinsing/wetting head in a bucket as I go. When finished hull requires a lot of rinsing.

 

[Varne27]

Exactly

Cheaper at toolstation,
need https://www.toolstation.com/pole/p50469
and https://www.toolstation.com/swivel-sander-head/p12186

But I found their 120 grit sanding mesh too fine for areas with a lot of layering. Got better results from 60 grit sanding mesh (from ebay etc.).

In use, I wet an area of hull with hose, then use mesh, rinsing/wetting head in a bucket as I go. When finished hull requires a lot of rinsing.

I do exactly as “ithet” with exactly the same tools. Except use 60 grit sanding mesh from eBay or amazon. This is reversible.

Did mine spring. After manually scraping off 20 years of “moonscape” antifouling the sanding seemed like a couple of hours of leisure activity! The pole gives you lots of leverage and keeps you out of the mess, so not particularly dirty

 

[Resolution]

Thanks for the replies. Turns out the device in question is a drywall sander, which plugs into a hoover and keeps the bulk of the dust down. Anyone got any experience of one of these? Could be a good, quick, clean solution?

Only seen them in use inside new buildings, sanding newly plastered walls. It worked very well, virtually no dust escaped from the powered head. But I fear that antifoul is going to clog the sanding head too quickly, and possibly clog the hoover as well.

 

[Marine Reflections]

I would opt to dry sand using a H class extraction unit, or at the very least an M class.

Forced rotation sander, with Abranet discs for maximum extraction and virtually no clog.

Ok, not a popular choice it seems even in the pro arena, but an H class unit ensures no dust excapes extraction.

Wet sanding is great at eliminating dust, right up until evaporation. Then you are left (or others are) with the particles.

 

[Marine Reflections]

Easiest way is to scrape with a 2 handed tungsten carbide blade which doesn't create much fine dust, followed by light dry sanding with random orbit sander with good dust extraction. Plenty of shop vacs around with good suction and HEPA filter - ordinary vacs won't collect the very fine dangerous particulates.

Yes, we are getting there chaps.

 

[MM5AHO]

I took a lot off with a vibrating scraper, when I did mine, but then there was 40 years worth on there about 2-3mm thick. The a pressure washer took most of the rest off. I collected the chippings, over 50 kg of it!

 

[dialdan]

Never tried it but how about an air powered random orbital and wet sand?

 

[Resolution]

Excuse the slight drift, but how dangerous are particles of old antifoul? I thought the way eroding antifoul worked was for the killing chemicals to leach out over a long period, leaving you presumably with a pretty inert base layer. If the paint has given up killing barnacles etc by the end of the year, then why are we scared of sanding the residue?

Time for a knowledgable chemist.