Powerwashing a hull without lifting the boat (& Coppercoat)

[MapisM]

I only recently discovered that the professional diver who also deals with docks etc. in my marina has a special equipment that allows him to powerwash just about anything, also underwater.
This is the thing he's using, and according to him it's very effective.
Now, I was wondering if anyone experienced this or similar equipments, and can confirm how effective it is for cleaning both the hull and the u/w gear.

Besides, I was thinking that this could be particularly interesting if I would treat the hull with CC, to avoid lifting the boat altogether.
But this diver I spoke with never worked on any Coppercoated boat before, and he suggested me to check if it can withstand the treatment, because it's allegedly too strong for self-eroding antifouling, for instance.
Now, my understanding is that CC withstands pretty well a normal powerwash with the boat on the hard, and I don't think that these underwater microbubbles can be any stronger, from a mechanical standpoint.
But any views are welcome!
Unfortunately, CC ain't very popular around here, and it's difficult to find reliable views on it, in general...

 

[vas]

P.,

on my custom copper epoxy a/f, this year I didn't pull MiToS out on the hard for a clean. So diver came and spent a good two bottles cleaning everything.
Now, fouling is horrendous down here, water temps are v.high and there was A LOT of stuff under there.
He asked me and I gave permission to use a hard bristle 150mm dia brush that is hydraulicaly rotated from a simple two stroke engine and a pump mated to it that was on the pontoon with loooong pipes to let him do the whole craft.
Worked a treat, during the season I dived a few times and cleaned again some areas of fouling plus the sterngear.
No problems whatsoever, so I'm pretty confident the microbubbles would be fine.

However, unless a pro around your area has it, there's no way you're going to be using it, 2K for the nozzle and 4-5K for the motor/pump, not exactly cheap is it?

cheers

V.

 

[Portofino]

I suspect cavitation will remove everything unevenly or @ least thin down the CC rapidly faster than you think .
I have marked stainless steel with cavition equipment ,inadvertently.
Then you will still have to change the anodes , bow thruster a bit diff with a snorkel. You have not said how competent a diver you are ?
There’s usually other jobs that are better done with the boat out of the water in a yard too .
So what’s the point of risking it ?
I thInk if it strips the CC off in patches or holes the gel coat or has a go @ the epoxi coating hmm risky .
I would be inclined to be a late adopter on this and head towards the back of the que .

 

[MapisM]

Just to clarify, I wasn't thinking for a minute to buy the equipment and do the job myself.
With a professional round the corner, who already has the equipment and the experience, it would be silly - not to mention that he's also a friend of mine.
Btw, in IT only pro divers with a specific harbour knowledge (hence specifically authorized by the local CG) can dive inside a marina for any reason.

Thanks Vas for reporting your experience.
If the CC resisted a direct orbital brushing, I can't imagine how that cavitation equipment could be more aggressive.
PF, which reasons do you have to fear the opposite?
What happened exactly with that bit of s/steel which you marked, and with which sort of equipment?

 

[Nick_H]

3-4 years ago I didn't get round to having the boat lifted and antifouled, so at the start of our summer holidays I bought a plasterer's trowel and glued a large scrubbing pad to it, then put scuba gear on and scrubbed the entire hull with it. It had been antifouled the year before, so there were only small patches of barnacles which needed a metal scraper, but the rest of the hull cleaned up nicely, and surprisingly quickly, with the scrubbing pad. I did a 57' boat on a single tank of air, and used positive buoyancy (no weights) to hold me against the hull.

In my experience, having had two of them, coppercoated hulls are very good at resisting crustaceans, but not so good at resisting weed and algae, so extrapolating my cleaning results above i'd say you wouldn't need the underwater blast washer in the link to clean a coppercoated hull underwater, just a big scrubbing pad.

 

[MapisM]

Thanks N, that sounds even better, because even if I should ask the diver to do that with his equipment, it would probably be a quick and easy job for him.

Btw, I didn't know/remember that also your boat is CC-ed. What's your view overall, worth doing?

 

[Portofino]

PF, which reasons do you have to fear the opposite?
What happened exactly with that bit of s/steel which you marked, and with which sort of equipment?

Surgical equipment.
Touching a retractor- you can engrave your name .

True cavition effect uses the Bernoulli effect ,it’s the energy from the exploding/ imploding bubbles that’s released that Is less harmful with water bourne soft tissues , but quite aggressive with hard tissues , the harder ie S/ steel it can mark it .

Just to be clear if it’s true cavition ( no reason to doubt Looking @ the blurb ) it’s not physically blasting stuff off like a super jet wash with extra high pressure , it’s the energy from the bubbles collapsing that’s doing the work .
That can be difficult to control I would have thought hence my reservations.

 

[Nick_H]

Thanks N, that sounds even better, because even if I should ask the diver to do that with his equipment, it would probably be a quick and easy job for him.

Btw, I didn't know/remember that also your boat is CC-ed. What's your view overall, worth doing?

I've only had small boats in UK with CC. As I said above, it stops any barnacles, tube worm etc attaching, but gets more weed and algae than conventional antifoul, which is easily removed with a scrubbing pad. I've no experience of using it in the med, Hurricane is your man on that score.

I didn't get it done on the Princess because it would have needed blasting, epoxy, then 5 coats of CC, and the quote in SoF for this was quite expensive (who'd have guessed? ) and I didn't know how long i'd keep the boat. If i'd known then that I would keep it 10 years or more i'd have done it anyway, to avoid some of the annual cost and hassle of lift and antifoul. Much easier to scrub the boat with scuba gear, or arrange a quick lift and powerwash at the start of a holiday. There are obviously other reasons you may need to lift a boat, so i'd only reckon on saving every other lift.

BTW, I'm very sceptical of the extra speed claims of CC, so I wouldn't use this as part of a justification to do it, but I think it can still be a good idea if you plan to keep your boat a good few years.

BTW2, how does the operator of the blasting tool you linked to stay close to the hull, you'd think it would be like releasing a balloon without tying a knot in the end?

 

[Bandit]

Personally I can’t see how the hull would be cleaned with cavitation , I smell snake oil.

cavitation is is a vacuum bubble caused by a prop, foil or high speed hull shape.

CC won’t be damaged by it.

If in the UK it’s good to lift again mid season to pressure wash and inspect the boat in the med I assume several times.

I still don’t rate cc

 

[MapisM]

BTW2, how does the operator of the blasting tool you linked to stay close to the hull, you'd think it would be like releasing a balloon without tying a knot in the end?

That's a good question, which I can't answer.
Will ask that chap the next time I'll meet him, but aside from boats, he does that job also on all sort of other u/w stuff (decks, chains, fish farms, whatever), so he surely knows how to deal with that.

Btw, this is also in reply to Bandit:
I couldn't be more far from trying to sell to anyone the equipment that I linked (just for reference) in my OP.
All I know is that the professional diver who told me about it bought it for his own job, and if it wouldn't work as it should, he surely would be the very first to stop wasting his time with it...

 

[MapisM]

Surgical equipment.
Touching a retractor- you can engrave your name .

True cavition effect uses the Bernoulli effect ,it’s the energy from the exploding/ imploding bubbles that’s released that Is less harmful with water bourne soft tissues , but quite aggressive with hard tissues , the harder ie S/ steel it can mark it .

Just to be clear if it’s true cavition ( no reason to doubt Looking @ the blurb ) it’s not physically blasting stuff off like a super jet wash with extra high pressure , it’s the energy from the bubbles collapsing that’s doing the work .
That can be difficult to control I would have thought hence my reservations.

Understood PF, thanks. I'll check also your concerns with that chap. :encouragement:

 

[Deleted User YDKXO]

.
Now, I was wondering if anyone experienced this or similar equipments, and can confirm how effective it is for cleaning both the hull and the u/w gear.
.

No experience of this equipment and no idea whether it can be used with Coppercoat but IMHO, hull fouling is not an issue in the Med providing you use an antifoul paint that is recommended by the locals but sterngear fouling is a major issue and responsible for most of the speed loss that every Med based boat experiences over a season. I can understand that the Cavitcleaner treatment would be too aggressive if used on normal antifoul paint but the big question for me is whether it can be used on sterngear without damaging it and whether it will actually remove the barnacles which adhere very strongly to sterngear in the Med because it looks to be a lot more efficient than a diver with a scraper

 

[Assassin]

Totally against it, this type of equipment was designed for cleaning subsea structures of heavy construction and it works well on them; it was never designed to be used on soft and relatively thin materials such as GRP and can do untold damage to it along with soft metals such as copper and brasses.