Mild HCL solution to clean barnacles from outdrive?

Murv

Murv

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Our first ever boat is out of the water, and for the benefit of anyone who's been following my threads the faulty outdrive is now repaired by replacing the transom pin :)
However, it's not easy to fully check operation as there are a lot of barnacles around the reverse lock mechanism.
The chandlery does a spray to remove them (or rather they usually do, it's out of stock) but I assume it's a mild acid solution anyway?
Any reason I can't knock up a mild hydrochloric acid solution to shift them?
 
Hmmm, OK, maybe a mild citric then! thanks for that, could've saved me some serious expense!
 
HCl is hydrogen chloride ... a gas which is very soluble in water.

Hydrochloric acid is a solution of hydrogen chloride in water and is available in a wide range of concentrations. Concentrated hydrochloric acid, as found on the laboratory shelf, is usually around 36% w/v

Muriatic acid is an old name for hydrochloric acid. It does not imply any particular concentration.

Anything capable of dissolving shell could very well cause damage to the aluminium parts of a drive leg so use with great care.


.
 
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Hydrochloric acid will attack Aluminium alloy even if anodised (as will sodium hydroxide solution). Having said that, hydrochloric acid is the best acid to use because it will dissolve barnacle shell calcium carbonate more rapidly than other acids such as sulphuric or phosphoric. It is also safer than sulphuric or nitric (this is relatively safer, not safe).

So not a good idea to soak your drive leg in hydrochloric acid (even if only using a 3.5% solution). If you do decide to use it then try to keep it mostly on the barnacles as already indicated by Vics. I can't think of a better chemical treatment off hand (well nothing easy to get and quick acting).

I just pressure wash barnacles and scrape off when still wet. They aren't that difficult to get off as long as you don't just leave them to dry and bond themselves tightly to the surface. I made the mistake of leaving them for a couple of days once many years ago. Never repeated the experiment and now scrape them off asap.
 
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Thanks for that, annoyingly it's been out for a week now.
The main body is clean, it's just the niggly little areas specifically around the reverse latch mechanism that are coated and that's the area that I really want to get to.
The plan is to use a weak solution in a spray bottle, leave it on just long enough to attack the shells then scrape them off.
I'll have plenty of fresh water on hand to rinse off afterwards.
 
Murv said:
Thanks for that, annoyingly it's been out for a week now.
The main body is clean, it's just the niggly little areas specifically around the reverse latch mechanism that are coated and that's the area that I really want to get to.
The plan is to use a weak solution in a spray bottle, leave it on just long enough to attack the shells then scrape them off.
I'll have plenty of fresh water on hand to rinse off afterwards.
Click to expand...

That's what I would do. The main thing is not to leave it "to soak", watch it like a hawk and any sign of it attacking the aluminium rinse it off. If there are loads of bubbles from the calcium deposits dissolving rinse it off too and then you can see what's happening, you can easily add more acid solution, you can't add more metal to your outdrive.
 
Do not use any dissolving agent.

Get used to it.There is no other way than to lay on your back and prise all those barnyules out from their little crevices,starting with the jet wash,then with a wire brush and finally screwdrivers and anything else that will reach up under into all those awkward tiddy little secret places.Be very very grateful you do not have two of the things........and remember ...your going to do it all again NEXT YEAR.Enjoy... :):):)
Ps.Bits of barnycule shell in the the eye are very annoying.
 
Where's your sense of adventure!
Quick squirt, quick scrape and it'll be clean as a whistle.
They won't come back next year, I'm going to stick a small "Strictly no Barnacles" sign on it when I'm done.
That'll show 'em :D
 
Razorfish said:
Machine Mart do an Aluminium Cleaner - bet its cheaper than acme Barnacle spray:

http://www.machinemart.co.uk/download/Clarkealuminiumcleaner.doc

Although I expect that the builders merchant brick cleaner will do the job just as well.

Andy
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Machinemart stuff is basically phosphoric acid, kinder on the aluminium alloy but also kinder on the barnacles as well. i.e. You'll need to leave it on longer than hydrochloric.

Brick cleaner is usually hydrochloric acid and attacks both aluminium and barnacles quicker than phosphoric acid.

Pay your money and make your choice I guess.
 
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