I hope the attached photo is good enough to see the dark & light spots on my hull. This is after wet sanding with 800 grit. I will move onto 1000 and then 1200. Since I have never wet sanded before, I was just curious if this is a normal thing.
Enlighten me--dark/light spots on hull
- Thread starter Windtherapy
- Start date
Did you first compound with something like 3M Super Duty? Were the marks there before you wet sanded or only after? General rule of thumb is to use the least aggressive agent first (polishing compound or rubbing compound), work up to more abrasive stuff in steps only if results not good, then stop once results achieved and then go back down the latter to the rubbing compound and finally a coat or two of non abrasive wax.
I also think that polishing with a product like 3M Heavy Duty would get a more uniform result. Follow with liquid marine wax.
I used it on the 30 year boat I bought a couple of years ago. I actually thought the hull was white when I bought it. But polishing removed the oxidation and brought out the true buff color and a nice shine (see photo)
I used it on the 30 year boat I bought a couple of years ago. I actually thought the hull was white when I bought it. But polishing removed the oxidation and brought out the true buff color and a nice shine (see photo)
Compounding alone won't get the job done (very well.)
Here's what else you'll need to do to get good results: http://forums.sailboatowners.com/index.php?threads/tips-for-a-great-buff-wax.117266/
Here's what else you'll need to do to get good results: http://forums.sailboatowners.com/index.php?threads/tips-for-a-great-buff-wax.117266/
I don't know if is normal or not, but to go thru the effort to eliminate random discoloration on an old boat seems way too exhausting to me. I always see the color imperfections in my old boat when I look closely. When looking from afar, she looks lovely.
I think that if you go thru the effort of wet sanding, compounding, polishing and waxing ... you've done enough. You might still have some discoloration, but your topsides will still be smooth and gleaming. That's more than good enough to put your tools away and go sailing!
I think that if you go thru the effort of wet sanding, compounding, polishing and waxing ... you've done enough. You might still have some discoloration, but your topsides will still be smooth and gleaming. That's more than good enough to put your tools away and go sailing!
I believe the marks were there last summer after I bought the boat but not 100% sure. I think I will clean it with FSR and see what happens. I am trying to get away from compounding etc. due to a torn rotator cuff. I need to get this baby in the water next spring for sure and have been doing all other things to it and I am done except for the hull, build a mast raising system and installing a composting head. I know several will go unglued on my nest statement but hear me out. I am planning on wet sanding it with 800 & 1000 and maybe even 1200 and then cleaning it and then using PoliGlow or FSR. I am not going to pay somebody 600-800 to compound and buff it for me. I purchased a pneumatic orbital sander with adjustable speed and wet sanded the first side yesterday with 800. I was hoping to go to 1000 next and then either FSR or Poliprep and then Poliglow. It may not be perfect but I really need to go sailing next summer. I have owned many powerboats but now I am itching to go sailing on the Great Lakes. Hell, I even bought a slip on Lake Huron and look forward to just playing around kayaking, fishing and sailing for a complete summer (our summers are short). UGH!
Orbital sander with 800 grit? Looks like you sanded through your gelcoat. That should have been a hand sanding job up to 1200 finished with compounding via an electric buffer. Just enough sanding to get through scuffs, scratches and heavy oxidation. And yeah, it is worth $800, probably more, because it is a lot of work.
I dunno. It looks inconsistent like gelcoat will look after sanding, but before compounding and polishing. Except for a few spots which might look a bit tan-ish, yellow-ish, which to me looks like tannin stains. I think some oxalic acid/On and Off/favorite acid based cleaner would help with that. 'Course, I would have hit with the acid bleach before sanding...
We had the same issue and found an easy solution. It worked so well, half of our club used it as well. We got our hull consistently and uniformly white.
What did it was the powdered Barkeepers Friend. A bit of it on a damp rag and the dark patches vanish. I'm sure it's the oxalic acid that mostly does it but when I tried pure oxalic acid it didn't do much.
You need to constantly add powder to the damp rag. Once the powder dissolved it stops removing the stain. Supposedly this stuff is mildly abrasive but I could not detect any visible abrasion.
Everyone who saw the boat borrowed the stuff and used it.
BTW I tried every other product including "on and off" and none did the same job.
Bonus - the stuff is cheap! It has to be the powder - the liquid does not do the same job.
Give it a try before you reject it...
Chris
What did it was the powdered Barkeepers Friend. A bit of it on a damp rag and the dark patches vanish. I'm sure it's the oxalic acid that mostly does it but when I tried pure oxalic acid it didn't do much.
You need to constantly add powder to the damp rag. Once the powder dissolved it stops removing the stain. Supposedly this stuff is mildly abrasive but I could not detect any visible abrasion.
Everyone who saw the boat borrowed the stuff and used it.
BTW I tried every other product including "on and off" and none did the same job.
Bonus - the stuff is cheap! It has to be the powder - the liquid does not do the same job.
Give it a try before you reject it...
Chris
Chris, hell that's worth a try. It's only $1.50 at Home Depot. Thanks for all the replies from everybody. I will pick some up today and report back.
It just looks uneven to me. I don't know if I would try wet sanding with a pneumatic orbital. I do it by hand. Put the sandpaper on a flat sponge for a backer. Usually side to side strokes. Sand each finer grit more than you did with the previous grit and it should come out nice and even.
What is the original color of your gel coat? Some boats in the 80's used an off white color. The darker parts might be the original and the white is the oxidized part. I am with Scott T-bird, I have some slight imperfections but from a distance it looks fine. Also, if you read Mainesails directions he specifically says to do the wet sanding by hand.
My gelcoat looked like that too after wet sanding. I figured it was normal for a 36 year old gelcoat having it's thin and thick areas. I know when I pulled the original cove strip off, the gelcoat under it stood proud of the exposed gelcoat by quite a bit. My gelcoat is thin and old, that's why I am not going the wet sanding/waxing route this time and just use Poli-glo. I heard it's great if you do your yearly maintenance.
Ya the boat looks awesome from about 50 feet if the light is hitting it right. I just picked up the Barkeepers stuff and will give that a try tonight or tomorrow.
I can't hand sand it unless I want physical therapy for my rotator cuff again and that was 8 weeks last year. It'll be Barkeepers to see if those dark spots will go away, then orbital sand (I do it very lightly and keep it wet all the time) an then Poliprep and then Poliglow. It'll have to be good enough. I have other stuff I have to do before snow comes and that can be in October some years.
I can't hand sand it unless I want physical therapy for my rotator cuff again and that was 8 weeks last year. It'll be Barkeepers to see if those dark spots will go away, then orbital sand (I do it very lightly and keep it wet all the time) an then Poliprep and then Poliglow. It'll have to be good enough. I have other stuff I have to do before snow comes and that can be in October some years.
The issue I have is how does a newbie like me to wet sanding know when his job of wet sanding is good and one can move to the next step? So lets say I go ahead with the 1000 and 1200 grit and then start the compounding steps and then whoops, wet sanding wasn't good enough so now start all over again.
Gonna go hit the side with the Barkeepers and see what happens to those dark spots. It's only 93 degrees out so what the heck--I'll grab a Sam Adams and scrub away.
Gonna go hit the side with the Barkeepers and see what happens to those dark spots. It's only 93 degrees out so what the heck--I'll grab a Sam Adams and scrub away.
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Just my opinion ... wet sanding with 800, 1000, 1200 is way too tedious and why such small increments? The only time I ever did much wet sanding, I started with 600 and jumped to 1200 and finally 1600. I only did that once and I wasn't very aggressive with the 600. I never knew when I was really done. I basically just sanded until the "feel" was consistent, which didn't take long. I just moved along and let my tolerance for tedium dictate how long to sand. Sanding for 30 to 45 minutes per side per grit was about all I could take. That would be about 3 to 4 hours of sanding (by hand), not counting breaks. That was about all I could tolerate, considering that at some point I was moving on to compounding, finishing and waxing.
I don't have much tolerance for tedious work like that.
I'm not sure what you intend to do if you are not compounding. If you are skipping that step, I would use 1600 grit at the end of sanding. I'd also be very wary of using a power sander. I'd go really light and quick in that case (and not use 600). You're past that step (with the 800). I would probably skip the next increment and spend more time with the 1600 grit if I was using an orbital sander. I don't have any reason, except that I would be afraid of being too aggressive with a power sander.
I think you would have to be excessively finicky if you looked at your compounding results and decided to go back to sanding when you are working on an old boat. Besides, you are applying a coating that fills in all of those micro grooves (that you can't see anyway). It seems to me that the preparation for poliglow is all about evening out the color and the incremental steps of sanding and compounding are far less important. The importance of the compounding and finishing really only applies to preparation for wax, where those micro grooves will more readily attract grime.
I don't have much tolerance for tedious work like that.
I'm not sure what you intend to do if you are not compounding. If you are skipping that step, I would use 1600 grit at the end of sanding. I'd also be very wary of using a power sander. I'd go really light and quick in that case (and not use 600). You're past that step (with the 800). I would probably skip the next increment and spend more time with the 1600 grit if I was using an orbital sander. I don't have any reason, except that I would be afraid of being too aggressive with a power sander.
I think you would have to be excessively finicky if you looked at your compounding results and decided to go back to sanding when you are working on an old boat. Besides, you are applying a coating that fills in all of those micro grooves (that you can't see anyway). It seems to me that the preparation for poliglow is all about evening out the color and the incremental steps of sanding and compounding are far less important. The importance of the compounding and finishing really only applies to preparation for wax, where those micro grooves will more readily attract grime.
Well, the short answer is you should have started with a buffer and a quality buffing compound like Presta Gelcoat Compound. It is about a 1200 grit, or so, and chances are better than even that you would not have had to wet sand the hull. You would have gotten enough clean and shine to get you out on the lake this season looking...OK. This can be a multi-year process, each year seeing your boat look better and better. In fact, that is a good way to approach everything in sailing - take it in steps and work on the important stuff first. For most of us it is a journey, not a destination.
RE: That rotator cuff, set yourself up with some kind of scaffolding and work all of this from no higher than your chest. You will be rewarded with newly reshaped Pectorals, Deltoids, and signature sailor-arm radialis. Your hand grip and calluses will let everyone know you are a guy who gets stuff done! You can cancel that gym membership. And your shoulder ligaments will thank you for caring.
RE: That rotator cuff, set yourself up with some kind of scaffolding and work all of this from no higher than your chest. You will be rewarded with newly reshaped Pectorals, Deltoids, and signature sailor-arm radialis. Your hand grip and calluses will let everyone know you are a guy who gets stuff done! You can cancel that gym membership. And your shoulder ligaments will thank you for caring.
What year is the boat? It looks like the gel coat is thin. Maybe it's had enough abrasives on it. I'd wax it up and move on to another project. Someday maybe paint it. If you don't like the $800 for waxing you are really not going to like the bill for a professional paint job.
Sorry about the rotator cuff. Been there, couldn't put the Tee Shirt on.
Sorry about the rotator cuff. Been there, couldn't put the Tee Shirt on.
Good points and some laughs everybody. Ya my rotator cuff was a high school hockey injury and never bothered me much until last summer when I started compounding the boat on a ladder. My God the pain came back after one side and then more physical therapy. Pain is gone no thank God. I pride myself on never paying anybody to do what I can do or learn to do. I am only 55 for Christ sake--that's young. So anyway, I did clean the one side tonight with the Bar Keepers Friend and it looks much, much better.
I do need to say this, I have seen some peoples photos on here showing their hull after just the compounding but before the wax and the reason I decided to wet sand this year and start over was due to my hull wasn't a 100'th as shiny as the pictures posted by others. I bought all the latest and greatest stuff most on here suggest (3M compound, 3M Finesse and Collinite wax) and also bought the nice Makita variable speed buffer but maybe I was doing something wrong--probably was but it sure felt right. All I know is I am done allowing the hull to eat up yet another summer. I am moving onto the other 20 things I need to do before winter hits and I have to cover the thing. I think I will say screw it and wet sand at 1200 and then PoliPrep and then PoliGlow and see what happens.
For those who sail Saginaw Bay or up near Oscoda, if you see a O'Day 26' with the hull not looking that nice, wave!
I do need to say this, I have seen some peoples photos on here showing their hull after just the compounding but before the wax and the reason I decided to wet sand this year and start over was due to my hull wasn't a 100'th as shiny as the pictures posted by others. I bought all the latest and greatest stuff most on here suggest (3M compound, 3M Finesse and Collinite wax) and also bought the nice Makita variable speed buffer but maybe I was doing something wrong--probably was but it sure felt right. All I know is I am done allowing the hull to eat up yet another summer. I am moving onto the other 20 things I need to do before winter hits and I have to cover the thing. I think I will say screw it and wet sand at 1200 and then PoliPrep and then PoliGlow and see what happens.
For those who sail Saginaw Bay or up near Oscoda, if you see a O'Day 26' with the hull not looking that nice, wave!
Did you try the "liquid" version of Barkeepers Friend? The powder does seem pretty abrasive. I use both on my top sides when trying to remove stains. Have not used it on my gray hull yet though. Some BarKeepers on a steel wool pad does wonders for my lifelines too.
Greg