How to restore this bottom

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newsailor72

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Jul 20, 2011
175
1974 Macgregor 22 SoCal - dry storage
Picked up a 84 macgregor, there are bunch of these white patches like this under the black paint, the seller thinks it's gelcoat (is it?) and that I could just apply new paint after some sanding, what do you guys think? He bought it last year but never got to take it out.

Also just noticed there is a very long, narrow scratch on bottom, probably caused by the trailer bunk. What is the fix? Widen it a little with a Dremel then apply some marine epoxy/bondo, sand then paint?
 

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Michael Davis

Michael Davis

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Jan 5, 2017
2,390
Beneteau First 38 Lyall Harbour Saturna Island
Clean (sand/ dremel) wipe with acetone, fill with thickened epoxy, sand and paint.
 
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JBP-PA

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Apr 29, 2022
620
Jeanneau Tonic 23 Erie, PA
That "scratch" looks awfully deep in the photo. Is it really just a scratch?
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,141
CAL 35 Cruiser #21 moored EVERETT WA
Perhaps some expectations are appropriate to establish.
You bought a boat that is over 50 years old. You do not plan to make it a showboat, bringing it back to the luster it had when it left the manufacturer. You want to go sailing.

With that in mind, I would follow the advice above of @Michael Davis.

I would inspect the gouge and be sure it is only surface-deep. Then, I would patch, Paint, and splash.

If it is beyond the surface and perhaps was caused by running into a rock that caused the scratch, then you may have more work to do.
 
degas

degas

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Aug 14, 2023
34
Tanzer 29 Lake Ontario
Looking at the photos, that scratch broke through the gelcoat and tore a layer or two of laminate. If the bottom is 6-10 mm thick, then your fingernail appears to reach about 30-50% into that. Yikes.

Does the area on either side of the scratch flex when you press on it from the exterior? From the inside is there any visible damage, like delamination or water seepage?

Personally, I'd be tempted to widen that scratch enough to put 1-2 layers of glass tape to make up for the damaged layers.
 
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F

Foswick

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Apr 25, 2024
532
Fuji 32 Bellingham
It looks like there is black paint over blue paint over white gel coat. It looks like the paints are just bottom paint (anti-fouling paint). That isn't really a problem. You just prep and apply new paint over the old. (You do need to know if you are painting over ablative or hard paint, and prep/paint accordingly.)

But, that long gouge is a problem. It appears to go well into the fibers. One of the advantages of an older boat is that the hull is probably thicker than it needs to be. So, this probably isn't a structural problem. But, you do need to repair that and not just paint over it. I would sand the entire bottom down to the gelcoat (but no more), fill the gouge with thickened epoxy, sand flush, prime, and paint.

Degas' recommendation about glass tape is not unreasonable - just hard to tell from the photo exactly how deep the gouge is and, more importantly, how thick the hull is that point. My hunch is that this isn't a structural problem, but I would give it some careful consideration.
 
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PaulK

PaulK

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Dec 1, 2009
1,408
Sabre 402 Southport, CT
Foswick said:
One of the advantages of an older boat is that the hull is probably thicker than it needs to be.
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MacGregor is not generally credited with ever building anything thicker than it needed to be. The scratch is worrying because it cuts into the fiberglass layup over a long distance. Exposed fiberglass cloth fibers could wick water into the inner layers and cause delamination. Lucky you're in SoCal and not likely subject to freezes, which would make the problem worse. If you repair the scratch without making sure it is as dry as possible first you will trap moisture in the hull which can cause problems later. If the previous owner hasn't used it for a year it's probably dry enough -- but don't run a hose on it! Repairing the crack by filling it with epoxygoop and then putting a layer of fiberglass tape over it, as @degas suggests, makes a lot of sense.
 
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N

newsailor72

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Jul 20, 2011
175
1974 Macgregor 22 SoCal - dry storage
PaulK said:
Lucky you're in SoCal and not likely subject to freezes, which would make the problem worse. If you repair the scratch without making sure it is as dry as possible first you will trap moisture in the hull which can cause problems later.
Click to expand
If I put it in water for trial first, how long should I wait before working on the gouge? I took a power washer to it yesterday, although I didn't wash the bottom, just the top side but Im sure water would have made its way to the bottom. I guess I can use a hair dryer or heat gun to expedite the drying process.

I pressed hard on either side the gouge, felt real solid, no flex at all.
 
Captain Larry-DH

Captain Larry-DH

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Jun 14, 2010
2,348
Robertson & Caine 2017 Leopard 40 CT
newsailor72 said:
If I put it in water for trial first, how long should I wait before working on the gouge? I took a power washer to it yesterday, although I didn't wash the bottom, just the top side but Im sure water would have made its way to the bottom. I guess I can use a hair dryer or heat gun to expedite the drying process.

I pressed hard on either side the gouge, felt real solid, no flex at all.
Click to expand
If it looks dry go ahead and start sanding. That will help drying by exposing more subsurface. Keep it dry until you’ve completed repairs.
 
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N

newsailor72

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Jul 20, 2011
175
1974 Macgregor 22 SoCal - dry storage
Captain Larry-DH said:
If it looks dry go ahead and start sanding. That will help drying by exposing more subsurface. Keep it dry until you’ve completed repairs.
Click to expand
reason i need to put it in water now is because it needs to be inspected and measured by the marina office while in water (not on trailer) by Jun 1st in order to get the boat slip. so just wondering how long I'd need to wait afterwards, given im in SoCal area.
 
Captain Larry-DH

Captain Larry-DH

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Jun 14, 2010
2,348
Robertson & Caine 2017 Leopard 40 CT
newsailor72 said:
reason i need to put it in water now is because it needs to be inspected and measured by the marina office while in water (not on trailer) by Jun 1st in order to get the boat slip. so just wondering how long I'd need to wait afterwards, given im in SoCal area.
Click to expand
Same answer. (Marina office is incompetent if they can’t do it on the trailer)
 
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PaulK

PaulK

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Dec 1, 2009
1,408
Sabre 402 Southport, CT
If you have to launch it for "marina inspection" it might be a good idea to put some good duct tape (Gorilla?) over the entire length of the scratch to try to keep it dry while it's in the water. Don't leave it in the water for longer than necessary and dry it off asap afterwards. Letting it dry a week or two after that with no rain or other moisture on it (make sure it stays dry) would be helped with a shot or two of hair dryer action. Some will say longer times, some shorter times before you start repairs. You decide.
 
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newsailor72

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Jul 20, 2011
175
1974 Macgregor 22 SoCal - dry storage
If I fill the gouge now and fiberglass it later, what's a good filler for the job, west system 610 or marine tex or something else?
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,141
CAL 35 Cruiser #21 moored EVERETT WA
Total Boat products are high-quality items, sourced from Jamestown Distributors.
 
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