grind... sand

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Rich (P303)

Rich (P303)

.
Jun 1, 2005
772
Pearson 303 Robinhood, ME
What would you use to rough up the old bottom paint before a new application? 4 1/2" grinder with a sanding disk... or a 5" orbital sander with a hook disk? I have 20 years of bottom paint... don't want to strip it... but would mind taking off a little more than I put on each year. I am using Interlux Bottomkote hard paint at the moment (what PO was using)... might change to an ablative in time.
 
Rich (P303)

Rich (P303)

.
Jun 1, 2005
772
Pearson 303 Robinhood, ME
What would you use to rough up the old bottom paint before a new application? 4 1/2" grinder with a sanding disk... or a 5" orbital sander with a hook disk? I have 20 years of bottom paint... don't want to strip it... but would mind taking off a little more than I put on each year. I am using Interlux Bottomkote hard paint at the moment (what PO was using)... might change to an ablative in time.
 
Ross

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
NOT a high speed disk grinder! Just use drywall

mesh sanding screen and a bucket of water. You don't need to paint every year if the the growth at the end of the season is within limits.
 
Ross

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
NOT a high speed disk grinder! Just use drywall

mesh sanding screen and a bucket of water. You don't need to paint every year if the the growth at the end of the season is within limits.
 
S

s sauer

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Jun 4, 2004
844
Hunter 28.5 Tolchester, MD
20 Year Build up?

If the existing paint is epoxy, vinyl or any other hard based non-ablative paint, I'd use an orbital sander with perforated 80 grit discs and connect the dust bag attachment to a shop vac. Wear a mask and a tyvec suit and scratch sand the paint down to uniform surface without craters and re-paint with a compatible paint. If your boatyard does not allow dry sanding, you may need to wet sand with heavy grit wet-or-dry paper and catch the wash-off debris on burlap for disposal. If you change to an ablative paint you may need to scrape all the previous paint off depending on the manufacturer's recommendations. At that point a chemical stripper or hand scrapers might be worth considering. There are lots of posts on this in the archives.
 
S

s sauer

.
Jun 4, 2004
844
Hunter 28.5 Tolchester, MD
20 Year Build up?

If the existing paint is epoxy, vinyl or any other hard based non-ablative paint, I'd use an orbital sander with perforated 80 grit discs and connect the dust bag attachment to a shop vac. Wear a mask and a tyvec suit and scratch sand the paint down to uniform surface without craters and re-paint with a compatible paint. If your boatyard does not allow dry sanding, you may need to wet sand with heavy grit wet-or-dry paper and catch the wash-off debris on burlap for disposal. If you change to an ablative paint you may need to scrape all the previous paint off depending on the manufacturer's recommendations. At that point a chemical stripper or hand scrapers might be worth considering. There are lots of posts on this in the archives.
 
higgs

higgs

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Aug 24, 2005
3,736
Nassau 34 Olcott, NY
Agree - no grinder

If your concentration drifts off they can really do damage quick and it ain't like bottom sanding is a job that doesn't get monotonous. I also like the orbital with 80 grit. I will take off a lot of paint quickly, but as long as you keep it moving you won't cut into fiberglass. i learned my lesson with a grinder when i hit a rough spot and it jumped on me a put quite the gouge in my hull.
 
higgs

higgs

.
Aug 24, 2005
3,736
Nassau 34 Olcott, NY
Agree - no grinder

If your concentration drifts off they can really do damage quick and it ain't like bottom sanding is a job that doesn't get monotonous. I also like the orbital with 80 grit. I will take off a lot of paint quickly, but as long as you keep it moving you won't cut into fiberglass. i learned my lesson with a grinder when i hit a rough spot and it jumped on me a put quite the gouge in my hull.
 
Rich (P303)

Rich (P303)

.
Jun 1, 2005
772
Pearson 303 Robinhood, ME
Sand it is...

I used a vibrating sander last year... roughed it up, did its job. An orbital sander with a hook disk and a collection bag would be quicker I think. I'll give that a try next spring. I don't want to take too much off... and actually get down to fiberglass... as I don't have any signs of blisters... so something must be right on this old boat. I do not believe I have a barrier coat... just 20 years of hard paint. I would like to get it down to ten! Thanks, Ross, Higgs, S. Sauer Have a Happy New Year
 
higgs

higgs

.
Aug 24, 2005
3,736
Nassau 34 Olcott, NY
Sander

If the sander you used was a finishing sander, you will be amazed at how much more material the random orbital takes off.
 
higgs

higgs

.
Aug 24, 2005
3,736
Nassau 34 Olcott, NY
Sander

If the sander you used was a finishing sander, you will be amazed at how much more material the random orbital takes off.
 
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