One of the things I put on my "correct after purchase" list for my new boat was that the top stripe was oxidized (pretty common for boats that spend all summer on a buoy in high-UV Tahoe), and that the blue gel coat below the rub rail had quite a few water spots and felt rough and dry to the touch. The oxidation came off pretty readily and wasn't a big deal to correct. The waterspots on the other hand....




I started with a good washing with a brush and hot soapy water. No improvement so I broke out the trusty Porter Cable orbital buffer with marine Meguiar's cleaner wax. No improvement. Next try was some Meguiar's #49 which is designed to remove oxidation and had worked well on the upper stripe. It seemed to help a little, but it would have probably taken three years of work to get rid of all the spotting so I gave up in search of a better method.

While looking through Meguiar's website, I saw they had a product specifically for water spots. Nobody in town had it, but I picked up two similar products (both smelled very acidic), one of which the boat shop said would take anything off. Neither one did anything.

At this point, I checked with a guy on my dock who details boats for a suggestion. He said I'd need to use a rotary buffer with a wool pad and recommended 3M Super Duty compound. A trip to Harbor Freight and the local automotive paint supply store later, I had a rotary buffer, wool pad and a big bottle of 3M compound.

After learning how to use the rotary buffer and figuring out how much compound to use, the spots finally started coming off. I probably spent 5 or 6 hours on the first side of the boat before I was done compounding. Working a rotary buffer back and forth with sustained pressure for that long is hard on arms, the back and shoulders - I was more sore last night than I have been in a long time. After compounding, I put a coat of wax on it and called it a day.

When I looked at it today in better light, there are still a couple of spots that needed more work, but that will have to wait for another time. The after:




and:




I got about a third of the other half done in 45 minutes today, so there is definitely a learning curve to using the buffer and compound.

Much, much more work than I thought going in. I never knew waterspots could be that difficult to remove.

Wow. That's a beautiful boat. Looks brand new at the end! Congrats!

The pontoon logs on our party cruiser were caked with calcium deposits. Actually, the insides under the boat still are--but I found an easy way to get it all off. I found that either "the Works" toilet bowl cleaner (from Walmart for about $2 a quart), which is 20% hyrdrogen chloride, or 20% muriatic acid (in gallons from Lowes for around $6.50, the stuff at Home Depot is only 14%) work about the same. I used around a 4 to 1 mix of acid to water, in a 1 gallon pump garden sprayer. At first I used a brush, but found that just repeatedly spraying did just as well. I sprayed about a 6' length of log, as if I was painting it. The acid only works for about 5 seconds before the calcium neutralizes it. Just keep spraying. You know it's working because it foams up when it comes in contact with any calcium. If it's not foaming, there's no calcium. A gallon of the mix was good for totally cleaning about 10' of log. Took about 2 or 3 minutes per square foot. But there's no work other than pushing the spray trigger and pumping the tank every once in awhile.

I found that the acid mix has absolutely no effect on the aluminum itself, only the calcium. And all the guck dripped constantly on the trailer. I just rinsed it off, it had no effect on the paint either. (which isn't waxed btw)

If it'll get 1/16" thick calcium off, I'll bet it'll get your waterspots off.

A less drastic approach that might work is good old white vinegar...

Glad you got them off. But yet another reason not to get a boat with such a wide dark hullside color!

Hate to ruin your day but a 50/50 mix of distilled white vinegar and distilled water, sprayed on and wiped off with a towel, would have taken them off the whole boat in about 15 mins

But your boat looks beautiful now! That's my favorite color on those, Classic Navy

Billy,
I've had 3 boats with full Navy Blue hulls and I have a black one now, don't regret any of them one bit.

One thing I learned in the plumbin' biz is that hard water "spots" will actually etch the gel coat on fiberglass tub/shower modules, if not wiped down regularly. Once they are etched in, they won't wipe off with vinegar or anything else. I don't know if this also applies to boats, but it might.

Wow, your boat does look great.

This stuff works great. Wipe it on with a rag, let it sit for a few minutes, then hose it off. Wash to remove all of it from the surface and hose off the trailer. It's available at any grocery store and probably Lowe's/Home Depot, etc.

I sure wish I could have found something to spray on and wipe the spots off. I forgot to mention it, but vinegar and water was one of the first things I tried. I also tried a hull cleaner with muriatic acid that I've used with great success in the past to remove hull staining from boats that have been in the water for extended periods, but it didn't have any effect either much to my surprise. It is very aggressive stuff and will take the paint off a trailer if you don't hose it off. I've heard good things about CLR, and I'll give it try. If it doesn't work, at least I can use it around the house.

From doing some research on the web, what happens if the spots stay on long enough is that as 2suns describes, they get etched into the gel coat and can't be removed by wiping the surface. At this point, I'm pretty sure that's what happened here. The boat sat on a buoy at Lake Tahoe for two years, and I'm guessing was never wiped down or waxed during that period. At least I don't have to feel so bad about not going to the gym last week.

Billy - my first choice would have been a boat with just the Navy stripes rather than the Navy sides, but this one was priced well and too nice to pass up. I've always vowed to never own another black car, and ended up getting a boat that is just about as bad. The upside is that is does look really nice when it is cleaned up. Unfortunately, like a black car, "clean" won't last long. I'll add a 5 minute wipedown with an Absorber towel to my list of things to do when I get back to the marina so the spots never reappear.

With all the chemicals you've tried, sounds like etching is the culprit. Before we sold our house I took apart a double-pane glass window that had moisture inside from a bad seal (for a couple of years), figuring that I'd just clean it up and save the cost of a new window. After wiping the glass dry, it still looked wet and calcified...I poured straight muriatic acid on to remove the calcium deposits, all that came off was a little white residue, the 'wet' was severely etched into the glass.

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