Applying antifoulant

[landonshaw]

I have pressure washed the hull and sanded with 80 grit paper. All barnacles are off. What remains is prior antifoulant and the white remained of barnacles, calcium. All is smooth although rough from the 80 grit paper.

Question: does the remaking calcium also need to be removed? I will be applying 2 coats of bottom paint. Thanks

[moctrams]

Use this product to clean up remaining. Good stuff.

https://www.jamestowndistributors.co...ct.do?pid=2339

[landonshaw]

Good stuff. I use it on the hull before compounding, polishing, and waxing. I skirt the bottom with a 2 ft wide piece of plastic to work as a guard keep it off of the bottom. It will take the antifoulant off. Does the calcium need to come off if it is sanded down? I am trying to preserve any old antifoulant that still covers the bottom.

Is this correct to do?

[tkeithlu]

What does the fine print on your paint say? Antifouling paint and bottom paint are very particular, and failure is expensive. Each manufacturer writes the rules, and calls the more diificult to apply stuff "professional only." Don't cut any corners....

[GordMay]

Barnacle remains need very thorough treatment, as their cement contains a hormone which encourages young barnacle ‘spat’ to settle nearby. So sand off all this cement until none is left. I’d use a coarse, 40- or 60-grit wet/dry sandpaper (to clean & “key” the surface), used wet to keep dust down.

[landonshaw]

GordMay, do you think that a wash down of on & off would help clean off the barnacles before sanding? Would it attack the prior coat? I might try a small area to see what the results are.

[GordMay]

I've never used "On-Off" Hull and Bottom Cleaner, so can't comment.

[moctrams]

Mixtures of On-Off

Water 80 - 90 %
Hydrochloric Acid 10 - 20%
Phosphoric Acid 3 - 5%
Oxalic Acid 1 - 3%%
Tallow alkyl amines, ethoxylated 1 - 3%

I have brushed on Muriatic acid to remove barnacles from props. Just spray down prop when you done and use eye protection.

[landonshaw]

Has anyone used muriatic acid on the hull to remove barnacles? I have used it on my dinghy and it worked pretty well.

[Cheechako]

I just left the white rings often. Removed the parts that sticks out.
Hey Gord, do you really think it attracts young barnacles when it's sanded smooth and coated with two coats of bottom paint?

[a64pilot]

Originally Posted by GordMay

I've never used "On-Off" Hull and Bottom Cleaner, so can't comment.

It’s a horrendously powerful acid, I think it will likely make short work of barnacle’s as I believe they are base.
However don’t get any of it on you, not even the mist on your arms, if you do it will feel like your arms are covered in fire ants.
I prefer the gel formula as it sticks and your less likely to mist it.

[AndyEss]

Originally Posted by landonshaw

Has anyone used muriatic acid on the hull to remove barnacles? I have used it on my dinghy and it worked pretty well.

AFAIK, muriatic acid is another name for hydrochloric acid.
Muriatic acid is commonly sold in many hardware stores to clean concrete.

[GordMay]

Originally Posted by Cheechako

I just left the white rings often. Removed the parts that sticks out.
Hey Gord, do you really think it attracts young barnacles when it's sanded smooth and coated with two coats of bottom paint?

Good question.
Barnacle settlement is a highly complex subject, way beyond my understanding.
Here's one (of many) papers, somewhat on the subject:
“Sensory receptor repertoire in cyprid antennules of the barnacle Balanus improvisus” ~ by Anna Abramova et al.
From the "Discussion"
“... A remarkable feature of barnacles is their complex settlement behavior allowing them to find a suitable attachment site for survival and reproduction. During settlement, barnacle larvae display a high degree of specificity towards surface chemistry and structure, as well as the ability to discriminate between conspecific and other barnacle species’ cues [42]. While some of the cues triggering settlement have been characterised, the exact molecular mechanisms of how cyprids receive these cues remain largely unknown. In the present study we identified three types of sensory receptors in the barnacle B. improvisus, olfactory ionotropic receptors, gustatory-like receptors and mechanosensory transient receptor potential channels, present in the cyprid antennules that most likely are involved in the sensing of settlement cues ...”
➥ https://journals.plos.org/plosone/ar...l.pone.0216294

[landonshaw]

Thanks, I will read tonight after some more scrapping.

[Cheechako]

Originally Posted by GordMay

Good question.
Barnacle settlement is a highly complex subject, way beyond my understanding.
Here's one (of many) papers, somewhat on the subject:
“Sensory receptor repertoire in cyprid antennules of the barnacle Balanus improvisus” ~ by Anna Abramova et al.
From the "Discussion"
“... A remarkable feature of barnacles is their complex settlement behavior allowing them to find a suitable attachment site for survival and reproduction. During settlement, barnacle larvae display a high degree of specificity towards surface chemistry and structure, as well as the ability to discriminate between conspecific and other barnacle species’ cues [42]. While some of the cues triggering settlement have been characterised, the exact molecular mechanisms of how cyprids receive these cues remain largely unknown. In the present study we identified three types of sensory receptors in the barnacle B. improvisus, olfactory ionotropic receptors, gustatory-like receptors and mechanosensory transient receptor potential channels, present in the cyprid antennules that most likely are involved in the sensing of settlement cues ...”
➥ https://journals.plos.org/plosone/ar...l.pone.0216294

Sounds a lot like Oysters.