Hull cleaning with a water blaster.

[Gina McLauchlan]

This is one carried over from the old forum

I need to remove some barnacles from the ships hull for an CP inspection. Does anyone know what a good pressure is to clean the hull with. We want to do as little damage to the hull coating as possible. My initial attempts are going to be at 5000 psi.

[Gina McLauchlan]

This is one carried over from the old forum

I did some mooring chains 12mths ago with a Nupro pump which was running at app 4500 psi and the results were not great, ended up using a stanley grinder with a chain flail which hammered the manip joints but provided great results.

Suggest you look at using 7500 psi as a starting point.

Cheers,

[Gina McLauchlan]

This is one carried over from the old forum

Thanks PMcK,

…you were right, 5k didn’t work. Had the nozzle 2″ from the barnacles. Didn’t even knock off the fuzzy stuff.

[Gina McLauchlan]

This is one carried over from the old forum

Are you wanting to use an ROV mounted jetting pump or is it for use by hand?

Have used various jetting pumps specifically designed for ROV use, none very effective for hard marine growth removal. Flow rate seems as important as the psi, I think one we used last year was only 12ltr/min, even though 7 or 8000 psi, could have pissed the marine growth off quicker. May be other better ones available, but have not used yet.

Most effective method I’ve used is by using a proper surface driven jetting skid located on deck, with the hose taped to ROV umbilical, the sort of jetter used by divers, don’t know manufacturers name, someone else on this site will probably know specs better.

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[Gina McLauchlan]

This is one carried over from the old forum

Skinny,

I’ve done some cleaning using a Neron HPP unit. Depending on the unit you choose, you can get up to 19400 psi out of them. Unit size is only 200x100x100 mm, so is small enough to vehicle mounted. You can also mount units in series. I’ve used a “fan jet” nozzle with good results.

If you end up using a surface fed pressure line, there’s a nozzle that creates a “swirling cone” effect by using a ball bearing inside the nozzle. Can’t remember any details like makers name etc, but it’s out there. I used one of these to clean away marine growth on the Magnus Platform a while back and it worked well.

Drop me a PM with your email address and I’ll email the specs of the Neron unit if they’re of use to you.

Cheers.

[Gina McLauchlan]

This is one carried over from the old forum

I have used pressure washers on ships with good results. We used 3000 psi wash with the “turbo tip” which amps up the pressure to 4500 psi (this nozzel makes a spiral spray pattern. Im assuming the ship is still a float so you are probably working in the 15 to 30 foot depth range. You have to put the nozzle right on what you are blasting. the problem with using a 40,000 psi water blaster is you will remove the antifouling paint. your other options are to remove it by hand (wire brush and scaper) or using a hydraulic scrubber (for large areas) Obvously the deeper you go the more you will have to compensate for ambient pressure.

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