Restoring An Oxidized Hull

GeneraiT001

GeneraiT001

.
Sep 8, 2025
125
Bayfield 36 Lewisporte
Hi,
Been looking at YouTube videos on this but haven't found much of use. I was told by someone to use "McGuires" on it?

I'm guessing the steps would be to:

A) power wash to remove loose dirt/grime then wipe dry;
B) tape waterline;
C) apply anti oxidizer with a buffer of some sort and wool cloth?;
D) more buffing; and
E) finally wax with a buffer?

If thats the process can you recommend appropriate products as well as a good buffer and wool buffer thingies :)

Thanks
 
GeneraiT001

GeneraiT001

.
Sep 8, 2025
125
Bayfield 36 Lewisporte
kappykaplan said:
Check out this post:

Tips For A Great Buff & Wax

Buff Polish & Wax Try these products (for Gel-Coat only not intended for Awlgrip) The Cliff Note Version: Steps: #1-Clean the hull with an acid base cleaner like FSR, oxalic acid or On & Off to remove rust & tannin staining. (only if necessary) #2-Wet Sand by hand 600 (if real bad)...
forums.sailboatowners.com
Click to expand
Thanks!!
 
jssailem

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,727
CAL 35 Cruiser #21 moored EVERETT WA
If the Gelcoat is oxidized but still present, then the recommendation is a light sanding with very Fine sand paper then compound and polish. If the gelcoat has already been burned through then the direction is to prep for paint.
 
  • Like
Likes: Jkutyna and marcham
Davidasailor26

Davidasailor26

.
May 17, 2004
5,860
Beneteau Oceanis 37 Havre de Grace
kappykaplan said:
Check out this post:

Tips For A Great Buff & Wax

Buff Polish & Wax Try these products (for Gel-Coat only not intended for Awlgrip) The Cliff Note Version: Steps: #1-Clean the hull with an acid base cleaner like FSR, oxalic acid or On & Off to remove rust & tannin staining. (only if necessary) #2-Wet Sand by hand 600 (if real bad)...
forums.sailboatowners.com
Click to expand
:plus: This is the authoritative guide which I and several others here have followed with great success.
 
  • Like
Likes: Ward H, brazenarticle, marcham and 2 others
shemandr

shemandr

.
Jan 1, 2006
7,751
Slickcraft 26 Sailfish
Remember that you don't need a great buff and wax. You need an showable buff and wax. Depending on the oxidation level a succession of compounds, followed by a carnauba waxing will go a long way to make the boat present well. For topsides this would be maybe as little as two work days. The deck would take longer due to having to tape off non-skid and the irregular shapes. Still I did my Mark 25 cockpit with Maguire Fiberglass Restorer in about 8 hours to a notably improved state.
If you don't want to diy you can have a detailer do it for far less than painting. Look for an automotive guy - not the marine contractors. You'll lose control of the product used but the result will still show better.
I would go light on the power washer. An hour with a brush and detergent is enough to prep a surface for compounding. Maybe a wipe down with Acetone to remove previous wax.
 
  • Like
Likes: BAD ORCA, JBP-PA and GeneraiT001
rardiH36

rardiH36

.
Jun 21, 2007
2,118
Hunter Cherubini 36_80-82 Sausalito / San Francisco Bay
To follow up on shemander's Post#6, I also noted that the OP referenced power washing.

On this, just a suggestion if the boat is in marina. Check the lease conditions. Here in the San Francisco Bay Area, marinas prohibit all pressure washing. I have been in my marina for almost a decade. So no longer remember every one of the lease terms when I signed it. The other day I brought a pressure washer down to clean the difficult-to-remove dirt and some mold growth in the "nooks and crannies" of my non-skid. The non-skid is in good condition and the pressure washing would not have caused significant oxidized gelcoat to enter the water. So I felt OK to do it. But so happened that a marina employee was just finishing a task on the dock. He noticed me walking with my hand-held pressure washer. He called my attention to the lease terms: "Pressure Washing not permitted". Hand cleaning though is not prohibited. So I returned the pressure washer to my car and instead aggressively wire brushed (stainless steel bristles) the non-skid clean also using a concentrated "biodegradable" cleaner product. Then hosed down. Probably same result as far as quantity of oxidized gelcoat flushed into the bay. (Of course the "biodegrable" stuff went along with the hose flush which I wouldn't have used if power washed.) On the plus side, I benefited from the upper body exercise.
 
  • Like
Likes: GeneraiT001
J

Jkutyna

.
Sep 15, 2023
18
Hunter 33.5 Green Cove Springs
rardiH36 said:
To follow up on shemander's Post#6, I also noted that the OP referenced power washing.

On this, just a suggestion if the boat is in marina. Check the lease conditions. Here in the San Francisco Bay Area, marinas prohibit all pressure washing. I have been in my marina for almost a decade. So no longer remember every one of the lease terms when I signed it. The other day I brought a pressure washer down to clean the difficult-to-remove dirt and some mold growth in the "nooks and crannies" of my non-skid. The non-skid is in good condition and the pressure washing would not have caused significant oxidized gelcoat to enter the water. So I felt OK to do it. But so happened that a marina employee was just finishing a task on the dock. He noticed me walking with my hand-held pressure washer. He called my attention to the lease terms: "Pressure Washing not permitted". Hand cleaning though is not prohibited. So I returned the pressure washer to my car and instead aggressively wire brushed (stainless steel bristles) the non-skid clean also using a concentrated "biodegradable" cleaner product. Then hosed down. Probably same result as far as quantity of oxidized gelcoat flushed into the bay. (Of course the "biodegrable" stuff went along with the hose flush which I wouldn't have used if power washed.) On the plus side, I benefited from the upper body exercise.
Click to expand
Thank goodness I am in a marina that is a former Navy base and is so toxic, about the only rule they have is no spray painting and no sand/shot blasting which I believe are against the law everywhere in the US to begin with. Unless you can move your entire boat into a painting shed that is.

The pressure washing does a fantastic job of getting rid of all sorts of stains/mildew and whatnot and it stays clean for a good 6 months.
 
thinwater

thinwater

.
Mar 26, 2011
3,823
Corsair F-24 MK I Deale, MD
Jkutyna said:
Thank goodness I am in a marina that is a former Navy base and is so toxic, about the only rule they have is no spray painting and no sand/shot blasting which I believe are against the law everywhere in the US to begin with. Unless you can move your entire boat into a painting shed that is....
Click to expand


No, not hardly. Federal law is not like that, and neither is state law. A local ordinance, certainly possible.

Each marina can set its own rules, of course. Requiring tenting is common and neighborly too. Typically the tent will have a fan with HEPA filters. But not by wide ranging law.
 
  • Like
Likes: Captain Larry-DH
B

brazenarticle

.
Jul 8, 2012
142
Catalina 36 MKII North East
GeneraiT001 said:
Hi,
Been looking at YouTube videos on this but haven't found much of use. I was told by someone to use "McGuires" on it?

I'm guessing the steps would be to:

A) power wash to remove loose dirt/grime then wipe dry;
B) tape waterline;
C) apply anti oxidizer with a buffer of some sort and wool cloth?;
D) more buffing; and
E) finally wax with a buffer?

If thats the process can you recommend appropriate products as well as a good buffer and wool buffer thingies :)

Thanks
Click to expand
Power washing can be aggressive for deck fittings and stuff you do not want to leak. A bucket of warm water with some dawn detergent and a brush will remove most dirt and grime. If not a second pass will be needed, maybe some On and Off Hull Cleaner too. No point wiping dry unless you are in a rush.
As suggested above ( and in many threads before) follow the Tips For A Great Buff & Wax .
Bayfield made nice boats, no skimping on gel coat or fiberglass. With some hours of work but not a lot of effort you can probably make it look like new. There is a zen component in the work, if you don't fight the job it is relaxing, not hard. Use some tape markers to see where you've done some magic, step back once in a while to see the improvement.
MaineSail wrote up his method and updated it with different products over the years. It is still the bible. Gel coat compound (Presta) and a rotary (not dual action) buffer are key to preparing for Fleetwax 885.
 
  • Like
Likes: GeneraiT001
MikeHoncho

MikeHoncho

.
Dec 28, 2015
1,923
Laser, Hunter H30 Cherubini Tacoma
you need to view this process as just like sanding wood to a fine finish. Start course and work your way to super fine. If you do not remove the oxidation then you will have a real mess when you try to wax as it will not come off. Skipping courses will only smooth off the peaks of the finish. Gelcoat is alot softer than automotive finishes so its easier to work. I'd recommend not going straight to wet sanding as this will potentially thin out your gelcoat unnecessarily if you can get the same results with compounds which are alot less aggressive. Try a aggressive compound and see if it cuts enough and if it does then follow it with a medium cut then fine then a final glaze. Use a high speed circular buffer or a multiple pad high speed orbital. I use Maguire's because I know the product. I usually start with a heavy cut, then fine cut then showroom glaze. If I have to really grind on it I will use a medium cut between the course and fine. The showroom glaze makes it pop.
 
  • Like
Likes: GeneraiT001
B

BAD ORCA

.
Nov 6, 2020
489
Mariner 36 California
3M makes a three step polishing kit for car finishes. They also sell the polish pads to use with each compound. I have used them on polyester resin in the past and they can produce a very fine finish.

3M™ Perfect-It™ System Buffing Kit

"The most popular in paint finishing!" Professional buffing system for use on today's paints ... expect the best possible finish. SAVE with this kit! Includes one of each 3M™ Perfect-It™ products: 4 buff pads, compound, and 2 polishes - for a complete buffing system. Made in USA. 3M™...
www.tptools.com www.tptools.com
 
Last edited:
B

BAD ORCA

.
Nov 6, 2020
489
Mariner 36 California
shemandr said:
Remember that you don't need a great buff and wax. You need an showable buff and wax. Depending on the oxidation level a succession of compounds, followed by a carnauba waxing will go a long way to make the boat present well. For topsides this would be maybe as little as two work days. The deck would take longer due to having to tape off non-skid and the irregular shapes. Still I did my Mark 25 cockpit with Maguire Fiberglass Restorer in about 8 hours to a notably improved state.
If you don't want to diy you can have a detailer do it for far less than painting. Look for an automotive guy - not the marine contractors. You'll lose control of the product used but the result will still show better.
I would go light on the power washer. An hour with a brush and detergent is enough to prep a surface for compounding. Maybe a wipe down with Acetone to remove previous wax.
Click to expand
I agree. I usually start with the finest compound first on a small area to see what the results look like. Its not always necessary to start with the most aggressive compounds.
 
  • Helpful
Likes: jssailem
You must log in or register to reply here.

Top Bottom