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Discussion Starter · #1 · (Edited)
I recently acquired an 1989 Catalina. Since buying it, I had the deck and hull waxed, and have washed it down several times. Earlier this week after a rain shower the blotches and stains appeared. Some were pinkish others were gray/black. I hosed them down but they persisted. Next day they were gone. Can anyone help me with this mystery?
 

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I have the same thing on my boat. Im currently in SE Florida awaiting the Xmas trade winds to die down a bit before proceeding further south.

My speculation/guess is that this is airborne bacteria, probably coming from Africa, and is using the wax on boats as its nutrient source, as unwaxed boats dont seem to have the problem. Also interesting was that this 'blush' when off central and northern Florida (NE trade winds) was 'reddish', in SE Florida (easterlies and southeasterlies) its more greyish. If it was dust from the Sahara it would be more 'yellowish', so my guess its probably bacteria as its quickly removed (bleached) by a wash with diluted oxalic acid solution. The recent sunrises and sunsets here have also been 'brilliantly yellow' which is unusual.
 

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Kynntana (Freedom 38)
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Are the blotches in areas where people with bare legs have sat? Might be the chemicals from sunscreen.
 

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You had the boat waxed? Deck and wax doesn't go well together:
1) difficult to clean as the anti-slip on the deck works against cleaning. Not to speak about removing old oxide and even the surface with rubbing etc, this is just not possible if one wants the anti-slip to remain.
=> deck surface will not be really cleaned.
2) wax makes the surface more slippery (there are special anti-slip waxes, but in my experience they are not good in any respect).
3) decks are usually horisontal. Moisture and dirt doesn't just drip away, but stays longer, some of it forever it seems.

The blotches you see can be any kind of dirt that was not really removed before waxing, combined with water / moisture. Can also mainly be just increased moisture in the wax. Disappears when the surface has dried. Comes back when new water is applied.

If you can't live with it (I would) then you have to completely remove the wax. Then you have to decide if you want new wax or not.

An alterntive solution is to paint the deck. Up-side is that there is no wax, no such issues - and you get a fresh deck in the color you prefer. Downside is that the deck need to be repainted now and then.

/J
 

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Discussion Starter · #6 ·
I misspoke. The waxing was of the hull and cabin top, the horizontal parts.

Jaramaz - while your explanation of it being dirt exposed by moisture makes sense, the mystery remains. It was not exposed during washing of the boat, only after it rained. Then they disappeared.
 

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Are you by any chance downwind of a boatyard? Sanding dust from copper bottom paint turns decks funny colors after exposure to moisture from rain or dew.

BTW, the best (and cheapest) product for removing stains from gelcoat that I have ever tried is Lysol toilet bowl cleaner in the squeeze bottle. Be very careful around aluminum though.
 

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looks like you polished thru the gelcoat to almost fiberglass...stop polishing. prep f or paint or gelcoating, which is prohibitively priced. is why folks paint their old fg boats.
I think we may have a winner here. Especially if you "had it waxed" as they normally use very high speed equipment and if they had a new kid they may have burned or took off to much gel coat. Welcome to the world of it is better to break it yourself rather than to pay someone else to break it for you, I mean do it your self, your not supposed to break things are you? :rolleyes:
 

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Discussion Starter · #11 ·
Thanks for all of your contributions. Any additional opinions will be welcomed. I will be compiling them in a brief email to the boatyard that did the work and see what they think.
 

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snake charmer, cat herder
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most 1960s cal and other hand laid fg ¡boats of of 1960s with overzealous owners and former owners become splotchy as the hand laying of glass after the hand painting into the mold of the gelcoat..which was, btw, quite thickly painted into the hull mold, will yield a dark grey to black coloration when gelcoat has been removed or nearly so.
a good surveyor MIGHT know what it is..i do know one who does.... but the yard may not say they know what it is or that it is their fault for over zealous sanding or polishing, which is same as a fine sanding especially when done by machine.
 

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Discussion Starter · #13 ·
Here is the answer from the boatyard. Opinions welcomed!

I have seen this staining issue before, it is caused by dirt/contaminates getting in the pores of the gelcoat. As boats age the gelcoat becomes porous which is why they lose there shine. The smooth shiny areas can be waxed to help seal the pores, but not much can be done for the non-skid as waxed non-skid kind of defeats the purpose. What looks like happened on yours is the rain had just enough acid in it to start lifting the contaminates out of the pores and then the boat dried before it was all of the surface, then the sun comes out and bleaches it out after a few days. Depending on if its an organic or mineral stain it can usually be removed with a little bleach and water or a mild phosphoric acid and water. (Just don’t mix the two). Also here are some commercially available products and a description.
The West Advisor: Gelcoat Maintenance

From your pictures it appears its all on the decks not the hull sides. Which is usually the case as the contaminates sit on flat areas.
 

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Are you located anywhere near the Florida Keys or the Biscayne Bay/Miami area?

In my previous post I stated that your (and my) boat rash looked like a bacteria. Well, it seems that the state of Florida has been very actively spraying for mosquitos that carry Dengue Fever and they use two different types of broadcast spray agents: one is a standard but non-toxic insecticide to kill the adult mosquitos, and the other is a BACTERIA to help kill off the mosquito larvae.
This aerosolized bacteria spray could quite possibly be what is on your boat.

This sprayed on bacteria is Bacillus Thuringiensis Israelensis ... the very same bacteria that is used at ski areas to enhance the output of their 'snow guns' - and we ski patrollers and skiers have had the same damn 'bloom' on our automobiles that are routinely parked at ski areas when they they are 'making' snow. The 'blooms' happen especially on those warm (above 32°) days after a long night of 'snowmaking'.

Info: Combating Dengue Fever | Florida Keys Mosquito Control District


Comments from your boat yard reply - If they waxed, then the open 'pores' of the FRG would be filled with wax - and side surfaces of your boat not surfaced with non-skid should not be affected, the pic with the 'windows' showing wouldnt have this 'bloom' showing. If what they stated was logical, they just admitted that either that they didnt do a good job of waxing or that the wax they applied does not 'shed water'. Nice 'dodge' by your boat yard but doesnt pass the 'logic' test.

My suspicion still stands - bacteria as a strong possibility. ;-)
 

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I've had rubbing compounds and wax leave behind residue that goes pinkish when they are not properly and fully buffed off or leave oxidation behind.

The grey is probably aluminum oxide - a residue left from rain, air planes dumping fuel and wash down from the mast.
 
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