Info required on grit blasting gear

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bluevelvet

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Looking for advice on equipment suitable for blasting my steel hull.I intend to remove 20 years of topside paint and a couple of spots where the original epoxy has failed.I dont mind buying or renting but do not know where to start looking and what to look for.Any advice greatly appreciated.Regards John
 
Things to bear in mind:
1) It's a physically hard and dirty job
2) You must wear protective equipment including a helmet fed with clean filtered air.
3) Dry open circuit blasting is bad for the environment, other boats and the health of anyone around and possibly illegal.
4) To do it legally it's necessary to screen off the boat for safety to protect bystanders.
5)The grit is heavy expensive to deliver and can cost a bit.
4) Buying the gear is going to cost two grand up, you probably won't be able to rent without training, but if you can it's going to cost a minimum of 150 pounds.
5) The equipment, especially the compressor is extremely heavy and will require a substantial vehicle to transport.
6) If you leave the equipment anywhere unattended it will be stolen.

It's only going to be worth it if you do a few. Possibly think about a small setup which will take longer but will be far cheaper, transportable it will do a far better job albeit slowly.
 
Thye most sensible thing you could possibly hear on this forum is "give it up!"

Get a company who do this all the time to quote you for the job, it may well be that you have to take the boat to them to do it. To give you an idea, you need a compressor feeding a positive pressure head/face mask, as no one wantws to breathe the oil polluted air from the main compressor this will be a separate one. Next you need a compressor to deliver the air, this will be a towed or lorry mounted machine, identical to those you see on the road gangs sites when they dig up the road. The blasting kit comprises hoses and a pot for the grit, the pot can weigh 1/2 tonne upwards, that's a Hiab crane job just to get it off the lorry. For a Boat around 30ft you'll need probably a tonne of grit if not more, bear in mind that will wind up all over the floor and you'll need a mini skip to put it all in. Next, screens and dust supression, I won't let you sand-blast if I'm anywhere near you on a calm day, let alone a breezy one. It is a Health and Safety no-no. So even with a professional company you are unlikely to be able to arrange to get the job done in your average marina - you need a proper commercial yard with facilities to do the work.
 
(1) Many steel boat owners do it.

(2) Grit can be:

(a) toxic silica (sand)

(b) less toxic black grit that is recycled slag from smelting copper, it's black, sharp and very abrasive

(3) less abrasive soda

(4) Professional grit blasters may suffer from inhaling the dust and/or isolation within the equipment.

(5) We had the steel bpoat grit blasted by a professional, and I learned that a hole in the hull is helpful to drain the grit.

(6) A froiend just had his 32 footer a Brent Swain. origami steel sailboat for the equivalent of a thousand pounds, inisde and out, I believe it was silica.

(7) See Yahoo group origamiboats and look for grit or sand blasting in the most active metal boat building group.

(8) We grit blasted much of the inside of ours after the profgessional left for the girders were impossible to reach with the large nozzle. We used a smal compressior 100 pounds per sq ich pressure, 4 cu feet per minute flow. for small spots. Cleaned girders to while metal slowly. Used carbon filter mask, double carbon filters plus felt filters on the outside. Inside of felt filters remained clean, contaminated on the outside. Carbon double filers frequently replaced with new.

(9) Could have sold hull and started fresh as a friend built a 42 footer in 10 1/2 weeks from first weld, using origami technique.
 
There is a professional firm established in sctoland whose name i forget - do a google search.

The kit costs lots, about 20k in all. Don't use sand, it's illegal and as deadly as asbestos when it breaks up on impact. Silicosis will make you just as dead as asbestosis.

Use a pro they charge about £12 ft of boat length but steel is easier to blast than GRP as you can use a courser grit, so aim for a deal.
 
John
Don't even think of trying to do it yourself ~ get a professional team in?

There are loads of reasons for getting them to do rather than you. You say "grit blasting" but popular opinion these days says "slurry" blasting is best!!!

These guys are doing it on a regular basis, are expert and have al the necessary insurances to cover any problems.

Down here in the "sarf" I can get slurry blasting done for £17-20 per metre. I know that your boat is steel but my guy can blast all the antifoul off a GRP hull without touching the gel coat?

My advice is ~ don't buy the kit or try to do it yourself ~ get a pro in on a fixed quotation and forget about it.

Peter.
 
There are companies that advertise in the local magazine. There is one in Kilmarnock that has done boats in Edinburgh but forget its name. There is no problem with this depending on what is used and a few boats have been done over the years in port edgar using sharp sand. SOme years ago when he was here I got him to do my keels which took about 20 minutes and he also cleaned of the old antifouling and where there were signs of blisters removed the gel coat under complete control. He could almsot take the antifoul off layer by layer.

Try your yellow pages or ask around at Kip or Largs.
 
Don't do it your self

This is how it was done on my boat.

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The firm used a big diesel engine driven compressor as used to dig up the roads
 
This is who you need to talk to:
http://www.marineblast.co.uk/
Clyde based and apparently very good/experienced.
There was another guy operating near Oban and his rig was sitting in the yard at Dunstaffnage in April/May. £36k was the price of the kit so I don't think it is something to be rented out. Mike at he Marina shop might be able to put you in touch with him, but from what I've heard, Marine blast are very good.
Care is needed as the wrong blast grit/pressure can easily do damage, so someone who is used to cast iron railings or stonework might not have the right knowledge about the sensitivities of cleaning down a boat hull.
I presume that you are aware of the need to immediately coat the exposed metal with a suitable primer/protection coat and not to leave that for another day........
 
I have my own kit for doing minor jobs which works very well. Its a 230 bar water pump with a karcher wet sand blasting kit which works using a vortex effect which cost about an extra 70 pounds. The sand is special and costs about pounds for a big tub. It works fine, but you still have to wear the protective gear and sheet off as described above.. (I use some temporary scaholding and a pile of tarpauline's which are pretty cheap to buy these days. ) I don't use the air compressor for breathing as I find it cumbersome. I use a very good breathing filter instead..

However if I could get my work done for £25 per meter, l wouldn't bother to use it as it is a dirty stinking job. I just blasted 15 yrs of antifoul of my boat last week.. A guy came up to me the last day and told me he charges £1000 to soda soda blast a similar boat of the same area... I would gladly have paid him that to do it. I guess whats nice about my setup is that I can use it for other things as well.. (works great for cleaning brickwork etc)
 
Where do they blast for £12 per foot???

Hello Elessar,

Can you tell me where did you find a pro blasting metal hulls for £12 per ft?

I want to grit or sand blast a 36ft steel Bruce Roberts (located in Kent) and the quotes I am getting ate around £2000 - £2500 for external hull only and more for hull plus deck. I think that this price is ridiculous, but that's what it is.

Please advise,

Thanks


Elessar said:
There is a professional firm established in sctoland whose name i forget - do a google search.

The kit costs lots, about 20k in all. Don't use sand, it's illegal and as deadly as asbestos when it breaks up on impact. Silicosis will make you just as dead as asbestosis.

Use a pro they charge about £12 ft of boat length but steel is easier to blast than GRP as you can use a courser grit, so aim for a deal.
Click to expand...
 
You can wet blast a steel hull, the water has a rust inhibitor in it. I bought a dry blasting pot from Ebay for £50. No hose or hogger and the pop up valve was rotted out. It cost £48 for the new hogger. and £10 a length for hose, I use four hoses. The helmet was a further £150 and the filter to filter breathing air was £100 and consumable filters £60 a pop. The new pop up valve cost me £60 to have cast in polyurethane (and half an hour in the lathe) as the manufacturer had gone out of business. This compressor cost £550 and is a two tool 130cfm ex Able plant. (They wanted £1000 deposit and £200 a day to hire) Hire of all the equipment is about £150 per day and the compressor extra. Hodge Clemco at Sheffield hire out pots and Copper slag is about £6.00 /sq.metre

Copper slag grit costs £120 a tonne. Dry"Sand blasting" is illegal. Other blast media includes Garnet, Chilled iron, Coconut shell, Walnut shells, ground corn cob and various synthetic foams. Bicarbonate of Soda is slightly different as the application rate is much less and it can be done wet using a good pressure washer and attachment. It will not profile the steel.
Oh did I mention that the compressor costs £200 to service and eats £40 a day in diesel.
Hire a company who will do in one day, what will take you three days to do.

Robin
 
If there are only a couple of spots where the epoxy has failed , perhaps it would be better to blast only those spots, and fair the rest.
If it aint broke, don't fix it!
Reminds me of a merchant seaman, who told me of a steel bulkhead on a ship, which was covered in an extremely rough, decades accumulation of paint . It was giving absolutely no corrosion problems of any kind. The skipper decided to keep the boys busy, so they chipped it down to bare steel and repainted it. After removing the thick coating, it suddenly began giving them all kinds of constant corrosion problems.
Simply fairing the roughness would have been a far better idea.

bluevelvet said:
Looking for advice on equipment suitable for blasting my steel hull.I intend to remove 20 years of topside paint and a couple of spots where the original epoxy has failed.I dont mind buying or renting but do not know where to start looking and what to look for.Any advice greatly appreciated.Regards John
Click to expand...
 
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