Removing barnacles

[ruvane]

OK, so I've been horribly negligent in the maintenance department, but I'm looking for the best method for removing barnacles from the GRP hull.

I'm not going to repaint yet, so this is just a temporary measure.

Is it better to do this while they're still wet and alive, or wait until they've dried out for long enough so that they're dead? How long do they survive being out of the water?

 

[Ecosse120]

used a plastic car ice scraper on mine and they all came of easily, I reckon it is easier when they are wet.

 

[William_H]

Barnacles will live for quite some time out of water if the shell is not damaged. If they are mussels big enough they can make excellent sea food.
However what you call barnacles may be mostly weed coral and any variety of shells. All need to be treated with a strong arm.
I have done some in water cleaning of much neglected boats. The best device I foiund was called a bricklayers bolster. ie a 10 cm wide cold chisel. It has a fairly blunt edge. The bolster has enough strength and inertia to smash the barnacles where a paint scraper or similar will just buckle. (and subsequently your fingers get cut something cruel) be carefull, wear haevy gloves.
For a boat out of water I have used a dutch hoe, long handle gets you out from under the deluge of fouling.
The requirements are that you remove the barnacles while not damaging the hull. You will need to do a lot of rubbing with wet and dry sandpaper to get rid of the last of the shell. An acid cleaner will help because most of the shells are lime based. Oxalic is popular while any other acid down to vinegar or lemon juice will work with varying speed. Leave it on a s long as possible ie 15 minutes before reapplying.

Good luck and shame on you. Boats need a steady flow of water under them. ie to be used. olewill

 

[H4B]

Hello Technolaser
A plastic bladed paddle from a cheap sea side inflatable works well. Knock em off pretty much as soon as the boats lifted.
Watching Ray Mears the other night it seems that its the sudden unexpected blow that removes them - if they sense impending attack they tighten their grip.

Cheers Howard

 

[ruvane]

Thanks guys, some really good ideas.

I'm concerned about any acid on the GRP. Are there any that are safe for short spells like 15 minutes?

I did try using a flat piece of olive wood which worked quite well, although aim was critical! I lost a number of bits of flesh which I only noticed when my hand dried. Also, in spite of only doing it for a very short time, I discovered some muscles in my arm that were not there originally.

Believe me, I would like to sail far more often but I have to work to pay for the thing or it'll get repossessed!

 

[VicS]

Grp is resistant to acids. The weak organic acids like oxalic, citric, or acetic are no problem but will disslove the bits of shell left fairly slowly and how you keep a sufficent quantity in contact with the hull for long enough to be really effective may be another matter.

Even a strong acid such as hyrodochloric acid (aka muriatic acid) and available in the Uk as brick cleaner will do no harm to the GRP. You would want to dilute it 5 fold, or even 10 fold if concentrated HCl.

Remember that oxalic acid is toxic and hyrdochloric acid corrosive so you would need some personal protection, for the eyes at least.

Personally I prefer to scrape them off asap as I have found that if left they cement their shells down firmly with the result that they they pull off rings of the A/F as they are scraped off. A scraper can be made of wood or plastic, A Dutch hoe with the corners rounded off is very handy or even a wallpaper scraper with the corners similarly rounded off and attached to a batten to form an extended handle.

 

[bobgosling]

[ QUOTE ]
You would want to dilute it 5 fold, or even 10 fold if concentrated HCl.


[/ QUOTE ]

Isn't there some very important rule about adding acid to water rather than water to acid when diluting ? ( Hope I got that the right way around ! ). Seem to remember from school chemistry lab days rather a long time ago that is would fizz and spit quite spectacularly if you got it wrong. I suppose kids wouldn't be allowed anywhere near such dangerous stuff nowadays.

 

[VicS]

[ QUOTE ]
Isn't there some very important rule about adding acid to water rather than water to acid when diluting ?

[/ QUOTE ] Yes if it is conc sulphuric acid, and very important to observe. With hyrochloric acid, which is only about a 36% solution of hydrogen chloride gas in water at most, it does not really apply although it is a good rule to follow in genaral to avoid mistakes. It will help to reduce the fumes a bit if using the real concentrated stuff but brick cleaner somewhat less concentrated. (I forget exactly what concentration it is.)

[ QUOTE ]
I suppose kids wouldn't be allowed anywhere near such dangerous stuff nowadays.

[/ QUOTE ] No such blanket restrictions but ordinary risk assessments would mean that it would not be used unnecessarily, especially with younger children.

They are very few materials or experiments that are totaly banned in schools but all are subject these days to risk assessments and the appropriate precautions taken.

See this page on the Royal Society of Chemistry's website if you are interested in reading further

 

[pelicanpete]

The Muriatic acid mentioned earlier in this thread is available in large quantities from swimming pool supply shops. I suspect it may be a stronger solution than the brick cleaning stuff, but could be wrong. It's used to balance the Ph in swimming pools. Here, in the Florida it's as cheap as chips. I feel sure it's readily available in the UK, even though the pools are ice rinks at times!

I've used this stuff on the bottom of my boat and the stainless steel props and it all came up like new. Take the necessary respiratory and eye protection precautions.

 

[VicS]

[ QUOTE ]
I suspect it may be a stronger solution than the brick cleaning stuff, but could be wrong.

[/ QUOTE ] If it fumes when you take the lid of the bottle it almost certainly is. If I remember all my facts correctly the stuff on the lab shelf labelled conc HCl is around 36% That definitely produces loads of fumes with moist air. Anything below about 20% doesn't fume.

 

[Colvic Watson]

The last two years the yard have used an ordinary water pressure washer and it took everything off - I mean everything, wouldn't have believed it if I hadn't seen it. It's probably a bit more powerful than my £35 B&Q jobby but not much. Try that first?

 

[Searush]

I carry an old garden hoe for the odd years I don't anti-foul. We pick a nice sheltered beach and have a day aground. It really sweeps 'em off a treat. The long handle gives you good leverage and keeps knuckles well away from sharp shells.

 

[fishermantwo]

[ QUOTE ]
IThe long handle gives you good leverage and keeps knuckles well away from sharp shells.

[/ QUOTE ]
I use a flat scraper blade made from a piece of gal sheet, 3 inches across and about 6 inches long. This is welded to about 6 feet of 1 inch water pipe. The handle has enough weight and momentum to knock off the shell and your far enough away not to cut yourself. The scraper is long ways on the end of the pipe and the side of the blade is handy for scraping prop shafts, leading edges of rudders etc. Also handy when scraping under the boat when snorkeling. The weight is important.

 

[PaulR]

cheapest quick way is to use a credit card (preferably swmbo's)

mind you could prove more expensive in the mid to longer term

 

[ruvane]

I have some HCl that I used to clean up the exhaust elbow and some other bits, but as VicS said, how do you get it in close contact with the hull for any length of time.

I really like the idea of high pressure water as pasta simon suggested, I just never thought it would have enough guts to get rid of these little blighters. As H4B said, as soon as they know you're coming, they hunker down and dig in!

As usual, thanks to all for a wealth of knowledge and solutions to the problem.