Sandblast antifoul removal or similar

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All_at_Sea

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In Southsea marina l want to take off the antifoul down to the gelshield layer on 42 ft hull. Has anyone any good experience of this with a local blaster/stripper? Any idea of cost. I see symblast mentioned a few times in the forum, any others out there?
 
The previous owner of mine did it last year.

Blast Master, Plymouth, 01752 863200

£475 for a 24' boat (Did a good job)

Then £492 to apply 2 coats of Gelsheild by the boatyard :eek: This does include preparing the surface properly prior to applying the Gelsheild.

You can apply the Gelsheild yourself a lot cheaper of course, roughly £100 with rollers etc, Easy job. :)
 
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Zagato said:
The previous owner of mine did it last year.

Blast Master, Plymouth, 01752 863200

£475 for a 24' boat (Did a good job)

Then £492 to apply 2 coats of Gelsheild by the boatyard :eek: This does include preparing the surface properly prior to applying the Gelsheild.

You can apply the Gelsheild yourself a lot cheaper of course, roughly £100 with rollers etc, Easy job. :)
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OK, so being a complete novice at this sort of thing, would this process (if done properly/professionally) produce a super-smooth hull - above and below the waterline?
Any drawbacks as to future DIY antifouling/hull polishing and/or repairing?
My boat was "painted" with an automotive pearlised paint and as well as scratches and chips, it is looking very tired.
Also the below-waterline is far from smooth and must be losing me speed.
 
All_at_Sea said:
In Southsea marina l want to take off the antifoul down to the gelshield layer on 42 ft hull. Has anyone any good experience of this with a local blaster/stripper? Any idea of cost. I see symblast mentioned a few times in the forum, any others out there?
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Symblast will do it for you. Price is based per ft length but will vary according to whether you want the keel done as well. Give Paul at Symblast a call and he will give you a fixed quote.
 
Robert Wilson said:
OK, so being a complete novice at this sort of thing, would this process (if done properly/professionally) produce a super-smooth hull - above and below the waterline?
Any drawbacks as to future DIY antifouling/hull polishing and/or repairing?
My boat was "painted" with an automotive pearlised paint and as well as scratches and chips, it is looking very tired.
Also the below-waterline is far from smooth and must be losing me speed.
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The broad answer is yes, it will give you a smooth surface ready for coating with either epoxy or conventional finishes. Not cheap if you do the whole lot including keel and topsides may need a lot of remedial work if you plan to get it back to supersmooth shiny finish. Minor imperfections below the waterline are less critical. Above will probably need a lot of fairing and a spray finish which is way more than a boat like yours is worth (No disrespect, just economics). Bottom definitely worth considering though.
 
Tranona said:
The broad answer is yes, it will give you a smooth surface ready for coating with either epoxy or conventional finishes. Not cheap if you do the whole lot including keel and topsides may need a lot of remedial work if you plan to get it back to supersmooth shiny finish. Minor imperfections below the waterline are less critical. Above will probably need a lot of fairing and a spray finish which is way more than a boat like yours is worth (No disrespect, just economics). Bottom definitely worth considering though.
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No offence taken. Thanks for the advice.
I intend to win The Lottery, and then I'll have her all Shipshape & Bristol Fashion, perfectly "tiddly" and gleaming like a new pin etc etc.
Any advice on which numbers to pick tonight?................:D:D:D
 
> take off the antifoul down to the gelshield layer on 42 ft hull

Sandblasting is normally done on metal boats to get to bare metal, I don't see how blasting could stop at the gelshield. If you have ever seen the power of a sandblaster it could easily go right through the hull. I wouldn't take the risk, sand it off.

We had a steel boat that we had blasted twice, watching it is awesome.
 
Hi
I had mine blasted last month 42ft long keel ketch cost £350 with falcon blast cleaning in essex,took all the old antifouling off down to the gelcoat nice job,
only does to within 3in of top sides so as not to damage the finish,cleaned up that part with sander with 80 grit paper,i needed to do it as i was copper coating
 
"Blasting" can mean several things, depending on the media used and the equipment. Sandblasting shoots dry sand in a compressed air jet and can be very abrasive. Slurry blasting uses sharp sand in a water jet and is thus more controllable (on GRP it leaves a fine eggshell finish, perfect for adhesion of new coatings). Soda blasting is supposed to be a little gentler still and I believe there are also dry ice systems which leave no extra residue to pick up beside the removed antifouling.

My own experience was DIY slurry blasting using a Karcher attachment. Being smaller and less powerful than a commercial rig it was slow and prone to hiccups when the sand got wet, but the plus side was that it was easy to control the cut so no extra damage risk. The finish was excellent for keying in the Coppercoat.

A competent commercial operator should be able to get the hull squeaky clean and ready for coating in a surprisingly short time, but the topsides will take a lot of work to get a really good result.

Rob.
 
Rob2 is correct re the varying aggressiveness of different blasting processes. I had my hull wet sand blasted a couple of months ago. It leaves a finish something like 80-grade sandpaper, ideal for adhesion of whatever you chose to put on next.

Bear in mind, though, that the Gelshield will not be very thick, so might need re-doing, at least partially. (Assuming it was applied in alternating coloured layers, this should be easy to identify: worth abrading a small area to check thickness/colours.) Any pinholes revealed by the blasting are best filled with epoxy.

If the keel is steel it might be better dry sand-blasted on a dry day and then epoxy primed immediately.
 
Have you spoken with the marina about what is acceptable to them and their position on run off ,removal of the blast residue and protection of adjoining boats.
 
macd said:
Rob2 is correct re the varying aggressiveness of different blasting processes. I had my hull wet sand blasted a couple of months ago. It leaves a finish something like 80-grade sandpaper, ideal for adhesion of whatever you chose to put on next.

Bear in mind, though, that the Gelshield will not be very thick, so might need re-doing, at least partially. (Assuming it was applied in alternating coloured layers, this should be easy to identify: worth abrading a small area to check thickness/colours.) Any pinholes revealed by the blasting are best filled with epoxy.

If the keel is steel it might be better dry sand-blasted on a dry day and then epoxy primed immediately.
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You're right it's thin - the dry film thickness of gelshield is approx 45 microns. If done properly though, as you say it should have 6 layers, alternating green/grey.

If blasted with our farrow system we will leave a mottled green/grey showing we will have partially breached the first of the 6 layers.

You could add 1 coat for good measure if you wish, but you would still have over 200 microns of epoxy left which is enough.

Yes epoxy filler is the way to go. Unusual to get pin holing on an epoxied boat though.

Also agree with you about the keel. Our machine has both dry and Farrow pots and we swap to do the keel. Want a job :)
 
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