View Full Version : Gelcoat Cleaning?

09-19-2007, 08:22 PM
About 9 months ago (close to the time we purchased our boat) I waxed the bottom of the hull from the bow back to the first crossmember of the trailer. I have recently noticed that the part I waxed still looks like new, but the rest of the bottom of the hull has started to yellow very slightly. I believe this is a result of the boat sitting in oily water in the river (which it only does when we go up the river to eat either lunch or dinner). Ninety five percent of the time we are in saltwater and it does not seem to be an issue then. The problem is that the yellow color seems to be in the gelcoat. I have yet to find a product or method to remove the stains. If anyone knows of something that will bleach out these stains or has conquered a similar problem, please let me know how to do it. Thanks so much.

09-19-2007, 09:06 PM
If you don't get a definate responce of what works, I would just head over to West Marine and Ask one of those guys, they should know what works and what doesn't.

I have noticed on the fishing and sailing vessals around here, that only go no more than 10 mph most of the time. You can see a light yellow stain on the bow of these boats were the water comes up and curls over. Just food for thought


09-19-2007, 09:10 PM

09-19-2007, 09:10 PM
Found this by google....


09-19-2007, 09:15 PM
Found this by google....Soooo

http://bajamarine.com/pdf/Removing_Yellowing_From_Gel_Coat_Surfaces.pdfThank s..........

09-19-2007, 09:52 PM
Salt water/ brackish water turns our white hull yellow....The cheap way is to use muratic acid (same as you use in the pool) mix 25% acid to 75% water, use a garden sprayer or paint roller w/pan....Wear long sleeves and rubber gloves....Start on the bottom v of the hull and work your way back to the sides, this will minimize risk of the mix dripping on you.....Spray or roll on, wait a minute or so....then spray off....I use this process and its amazing and much cheaper than West Marine stuff.......As with any cleaners, wax after use.....it will remove all the wax....Good Luck

09-19-2007, 10:01 PM
Probably the same stuff as state above, but you can buy starbrite hull cleaner from walmart and it definatly is cheaper than west marine, but probably not as cheap as making your own.

09-19-2007, 10:11 PM
If you do it on a cement drive way make sure to apply the acid with care and then wash the drive down or you will bleach the cement with an outline of your boat. Yes, I know from experience. I now take mine down to a self wash at off hours then dry and drag back for waxing, etc.

09-19-2007, 10:17 PM

Is the yellowing you experience in the gel or something that gets on top of the gel? I have tried a 50/50 mixture with bleach and water and it did nothing.

09-19-2007, 10:18 PM
By the way, thanks for the help everyone.

09-19-2007, 10:37 PM
Although it appears to be a yellowing of the gel coat, the good news is its just stained.....Just about everyone I know who boats in salt water has the same yellowing look. I tried the bleach option originally, it did nothing to remove the yellow. I spent big money on the professional stuff. I picked this info up from the locals, so I thought what the heck. Went over to the pool chemicals and mixed up some and it literally turned it back to it snow white color. If you dont have some muratic around the house for the pool, go to the pool store or loews.....3.00 gallon will take care of your needs for a long time.......Again, make sure you wax the boat after cleaning with any harsh product, they will remove the wax and the future cleaning will become more difficult. I am assuming you have an galvanized MC trailer, be careful with the cleaners, may spot it..

If you have any mold or mildew on your driveway, it will remove it instantly......I also use this mixture with the pressure sprayer instead of the 20.00 per gallon driveway cleaner.

Theres an XStar on a lift over on the IC by St. Pete....my son spotted the boat don't remember the color is that you? We go over to Egmont frequently.......beautiful island.

09-19-2007, 10:49 PM

Thanks so much for the help! I will be sure to pick some up and get the boat nice and white again. No, that is not our X-Star. We are located in South Tampa. Shoot me a PM next time you go to Egmont or are in this area, maybe we can get together. What boat do y'all take out to Egmont?

09-19-2007, 10:53 PM
Just a MC lurker now....We have a Cobalt now:o

09-19-2007, 10:56 PM
Oh cool. Is the mixture okay to spray on to decals? Just in case any over spray gets onto the decals.

09-19-2007, 11:22 PM
?? not sure....I have only used it on the hull and about 1 foot up the sides....my guess would be it would not harm the decals...since the muratic acid comes in plastic jugs...not sure about the adhesives....

09-19-2007, 11:36 PM
50% snowball tolet cleaner (walmart) 50% hydrogen peroxide (walmart). One day in the lake and I have a yellow scum thats almost impossible to remove. Spray it on and the yellow will run off. You will need to recoat with wax or 303.

09-20-2007, 12:38 AM
Keep the acid off the decals, that is strictly a HULL CLEANER. Also, it will destroy your vinyl!

You could also try Bio-Kleen Hull Cleaner which has worked for us, and is safer to use.

09-20-2007, 01:01 AM

Thank you very much for the advice.

09-20-2007, 08:31 AM
did you try "ON/OFF" You can get it at West marine and it does a FANTASTIC job!!!!

09-21-2007, 11:37 PM
THE WORKS TOILET CLEANER............. works great,,,,,,,,
don't let the misses know you know how to use it