KAL
Well-Known Member
I'd appreciate feedback from any members who've had their antifoul removed by blasting. Is one method any better than another? Can you remember what the charge was?
Many thanks!
Many thanks!
Antifoul removal by blasting
- Thread starter KAL
- Start date
savageseadog
Well-Known Member
I've actually done a few myself. A wet system is better than dry and that's about it.
philip_stevens
Well-Known Member
Had my last two boats wet slurry blasted. It leaves a good key for epoxying or anti-fouling.
rivonia
Well-Known Member
We had ours SLURRY blasted as it was the cheapest at the time. Then we had copper coat applied. Cant remember the cost though.
Peter
Peter
KAL
Well-Known Member
Can you recall the approx. cost Philip?
Elessar
Well-Known Member
in the solent we charge £12/ft for dry blast and £14/ft for a farrow blast. Would have to charge mileage so no point me coming to devon, but I hope the price point is helpful.
The guys at CopperCoat will give you a list of removal contractors in Devon if you call them
VicMallows
Well-Known Member
Elessar,
How 'selective' is blasting, in the sense of 'how well can it remove quite a thick A/F build-up without damaging the existing underlying epoxy coating' ? Which method is best in this context? Is it ALL down to the skill of the operative?
(If it is relevant, my hull was epoxied before first launch with Hempel solvent-based epoxy 26years ago and the epoxy coating is still in perfect condition so would not want to jeopardize that).
Elessar
Well-Known Member
It is a skilled job, and the higher the cfm of the compressor the more skilled it is. And dry requires more skill than wet (on GRP)
In a nutshell the faster it removes it the more skill is needed. It is done by eye, so you need to react quickly.
You can tell if someone has the "feel" for blasting quite quickly, we start them on keels that they can't damage. Often skilled sprayers can be good. They need at least twice as many hours to be able to dry blast GRP.
With solvented epoxy you are typically looking at approximately 50 microns dry film thickness. They will be applied in 6 layers in alternate colours if done correctly. 26 year old hempel will be beigy yellow and red I think, gelshield 200 is green and grey.
Once finished with a farrow blast (a hot wet blast) you will be left with a mottle of the 2 colours as we will have partially breached the 1st layer. ie we will have sanded off about 50 microns of your 300.
The nightmare is when the epoxy is not well keyed to the substrate. Then it will chip off. The remaining epoxy can't be blasted off as it is harder than the GRP. Don't believe a blaster that says they can. Sanding, or filling if the chips are isolated, are the only solutions.
VicMallows
Well-Known Member
Many thanks for the very comprehensive and informative reply. Plenty of food for though.
Vic
Elessar
Well-Known Member
You're welcome - are you in emsworth marina?
johnjfrake
Well-Known Member
For what its worth I had many years of anti-fouling and primer wet blasted off Calanda's bottom (she didn't complain) and it was worth every penny. Found that she had been epoxied, also couple of repairs that could stand improvement and perfect preperation for re-priming and antifouling. Would have taken me 3-4 days at least to prepare the hull to that standard.
wotayottie
Well-Known Member
Had it done by the Farrow system and the cost was, from memory, about £400 for a 34 foot bilge keeler. The result was first class including shifting some vinyl primer underneath the antifoul.
VicMallows
Well-Known Member
No, usually on a mooring nearby but presently ashore at Thornham. Not a project for this year (too much other boat trauma
)....but something I'm thinking about for next haul-out, probably in 2 years.johnjfrake
Well-Known Member
Having Calanda wet shot blasted cost about £600.00 from memory! very tidy worker, Carted all mess away and no damage to nearby boats.
