Yellow bio growth around waterline

[Utahsailor]

Less than 3 weeks after launch and hull cleaning and waxing, that old yellowish growth has migrated up about 4 inches above the water, mostly forward (white Beneteau). Is there any preparation that can be applied to the hull to prevent or slow down? The yard cleaned it off with Naval Jelly.

I wonder if one of those 3M films that are applied to cars could be loaded with a biocide that would release its toxins?

[St. Elsewhere]

Where is your boat located? Glacial till runoff in the PNW causes a yellowish stain on the bows of boats.

[Utahsailor]

No glaciers here- we are in Penobscot Bay, Downeast Maine

[robert sailor]

Try some "on off" usually does a perfect very quick,easy peasy job.

[Utahsailor]

But doesn't it require re-waxing the area On-Off used?

[belizesailor]

Originally Posted by Utahsailor

But doesn't it require re-waxing the area On-Off used?

Absolutely and quickly. Otherwise the gelcoat will absorb waterline stain worse than before.

[tinkrman69]

Hi Utahsailor.

I've only it happen to me once and I've noticed it on other boats, but not all boats. for me it happened when I was cruising up the Tombigby. on the other boats or some of them as I didn't spend time with all, were from areas that had rivers near by or marinas up rivers. Some rivers are high in heavy minerals, which would cause yellow staining on the hull. With Wax's you can protect the Gelcoat. but I've never heard of anything to stop it. 3M fiberglass restorer will clean and maintain it with not too much effort. use the light version and only by hand, so you'll only remove the previous wax and not the gelcoat. Wax is a sacrificial, just like the sunbrella sewed to the edges of a roller furling head sail.

[St. Elsewhere]

Originally Posted by Utahsailor

No glaciers here- we are in Penobscot Bay, Downeast Maine

Glacial till came from retreating glaciers that covered much of north america 12 to 15,000 years ago. Today it shows up as greenish water flowing from rivers into the blue water oceans. Often you will see turbid greenish water several miles into blue salt water bays. It does cause stains on fiberglass hulls, particularly on dull porous gel-coats. Buffing and waxing oxidized gel-coats will reduce such staining.

[leftbrainstuff]

Its common in the bay area. Apparently its a bio critter according to some of the locals.

I havent done any research but it polishes off.

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[BrianGJS]

It may not be the same yellow, 'mustache' the we experienced in the ICW or even locally in the Great Lakes, but we have had great success at removal with toilet bowel cleaner. Try a mild solution and if that doesn't do the trick, up the concentration. Follow with a good rinse.

[hellosailor]

Those 3M films are mainly a polyurethane. Manufacturing polyurethanes apparently is a rather expensive business due to associated pollution and toxic chemical issues, I'm told that is why Vredstein stopped making some damned fine sea boots 20 years ago.


But in any event, in the US, once you start building in "biocides" the EPA gets involved, and you have to deal with pesticide regulations, and life gets doubly complicated. For a product that is NOT designed for constant immersion in water.


Better to put the poison in a clear "varnish" and just paint it on, since there won't be much gravel damage to worry about on most boats.(G)


Kinda boring the way that stain is always yellowish, isn't it? I'd rather see someone figure out a way to make it glow blue at night. Then at least, it would be ornamental.


Or glow red on the one side, green on the other, and supplement the nav lights.(G)

[Cliff Meima]

Yellow stain on my boats' dull white fiberglass hull, are a common problem for me, regardless of the waters I cruise in. At my next opportunity I am going to clean it off again and then I will try Appling a small test patch of high quality paint. I suspect the paint will not stain like the hull does.

[Stu Jackson]

Originally Posted by BrianGJS

It may not be the same yellow, 'mustache' the we experienced in the ICW or even locally in the Great Lakes, but we have had great success at removal with toilet bowel cleaner. Try a mild solution and if that doesn't do the trick, up the concentration. Follow with a good rinse.

That's what we call it, too. On & Off GEL or FSR gel, followed by wax.

No wax, it will reappear right away 'cuz the removal process creates tiny holes in the gel coat.

Boats that don't have it? They never get used!!!

[Boatyarddog]

Sail it more often.


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