Dry ice blasting of antifouling

[Concerto]

Today I saw someone photographing the Sunseeker alongside Concerto in the Chatham Marina boatyard. Thinking it was the owner, I asked if it was his boat.

"No, I dry ice blasted the antifouling off".

As I had not heard of this process before, he explained how he had removed the antifoul from this 40 footer and took 16 hours working on his own. As he has a second rig, he can do a boat this size in a day. The regular valeting guy, Julian, will remove antifouling and he estimated it would take him and his assistant 5 days. He did apply the antifouling and completely compound the dark blue hull and white decks. Julian also commented that if he had removed the antifouling, he would have caught the gel coat in places. Whereas the dry ice did not mark the gel coat at all.

One of the big advantages of this method seems to be the speed and only paint residue that can be collected, nothing else. I asked about the cost. They charge £1200 per day plus travelling expenses and they will travel anywhere in the UK.

This is a new venture for Gransden Construction Ltd and are based in Sittingbourne, Kent, and the manager I was talking with is Andrew Phillips. The phone number is 01795 478487. They are primarily a construction and restoration building company. They purchased the equipment about 4 years ago to clean old timber beams in timber framed properties. Unfortunately planning delays and limited demand, means they have spare capacity. They have started removing antifouling. They have booked stand J272 at the Southampton Boat Show.

I have no connection with this company. Just trying to help them get some business.

 

[chrishscorp]

Yeah basically the dry ices is fired at the hull it expands as it thaws out and everything flakes off leaving the gel coat unmarked. Sometimes you can get a deal if there are several boats that need it done in the same yard. Timber beams and facing stonework needing cleaning use this process as it doesnt damage the surface pretty nifty really.

 

[Mistroma]

I was lucky when I did my 42' sailing boat in slightly less time than that. I used my Bosch power chisel and brushed the flakes into some buckets for disposal. Doesn't work with soft A/F, just stuff like Cruiser Uno etc. My previous boat had about 15 years build up, mostly International products and also came off easily with the power chisel. I tried it on a friend's boat but he'd used soft chewy A/F and it simply moved it around a bit. Dry ice might have been a good option for him if the A/F became brittle on cooling.

 

[Tranona]

It is more gentle than using a solid material, but very slow. With an experienced operator conventional blasting is just as effective on a GRP hull, quicker (less than half the time) and therefore cheaper.

Dry ice blasting has been around for a long time, but has never really caught on for boats because of the cost.

 

[cpedw]

How many trees does it take to offset the carbon footprint?

 

[chrishscorp]

How many trees does it take to offset the carbon footprint?

The only extra carbon being created is the carbon release from powering the blaster pump

 

[zoidberg]

I explored the use of 'abrasive air blasting' for antifoul stripping a few years ago. Then, I couldn't find a firm willing to come to me.
Instead, I hired a compressor and kit, and used 'soda' as the ablative material. This sodium bicarbonate stuff comes in 25kg bags, for swimming pool treatment, and is readily available.

The crystals are weak and shatter on contact - unlike sand and other industrial ablatives - so the action on antifoul and gelcoat is gentle. I learned as I went along, and was able to strip a 27' hull over 2 days of intermittent work. The cost? Well under £500.....

Beware of cheap Far Eastern control nozzles, which you grip to direct and control the flow. The 'gentle' soda blast through the ball-valve nozzle abraded through the cheap metal, directing the blast at my gloved hand at >4bars. I found a professional vendor of hydraulic equipment, who sold me some robust replacement nozzles. I was thankful for my leather gauntlets and eye-goggles. The used material is non-toxic, brushes/hoovers up, and the residue dissolves away in the rain.

I'd use that procedure again.

 

[DJE]

The only extra carbon being created is the carbon release from powering the blaster pump

Not if the CO2 is produced from natural gas.

 

[Frogmogman]

The only extra carbon being created is the carbon release from powering the blaster pump

…and of course from the energy used to refrigerate it in the first place (assuming that came from burning hydrocarbons.

if anything, dry ice blasting can be seen as a relatively benign technique from an eco point of view, as it may often be replacing the use of damaging chemicals.

 

[afterpegassus]

I explored the use of 'abrasive air blasting' for antifoul stripping a few years ago. Then, I couldn't find a firm willing to come to me.
Instead, I hired a compressor and kit, and used 'soda' as the ablative material. This sodium bicarbonate stuff comes in 25kg bags, for swimming pool treatment, and is readily available.

The crystals are weak and shatter on contact - unlike sand and other industrial ablatives - so the action on antifoul and gelcoat is gentle. I learned as I went along, and was able to strip a 27' hull over 2 days of intermittent work. The cost? Well under £500.....

Beware of cheap Far Eastern control nozzles, which you grip to direct and control the flow. The 'gentle' soda blast through the ball-valve nozzle abraded through the cheap metal, directing the blast at my gloved hand at >4bars. I found a professional vendor of hydraulic equipment, who sold me some robust replacement nozzles. I was thankful for my leather gauntlets and eye-goggles. The used material is non-toxic, brushes/hoovers up, and the residue dissolves away in the rain.

I'd use that procedure again.

What approximate quantities of soda was required for your hull blast?

 

[zoidberg]

What approximate quantities of soda was required for your hull blast?

I recall I used about 9-10 bags. Do ensure whatever is bought is fresh and very dry - as otherwise it swiftly clogs up the jet hose intake, needing cleaning out and reassembly. That slows the work flow.