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  1. #1
    Join Date
    Mar 2015
    Location
    London
    Posts
    54

    Default Hull treatment: can you recommend someone in South?

    My past survey said that this winter I have to do big hull treatment if I want to future-proof my boat as moisture readings are creeping up. I have only started to learn what it involves, but looks like big spend. I wonder if someone can recommend 'cheapish' place to do it anywhere from Weymouth to Eastbourne.
    The boat is 8.5 m long, based in Hamble at the moment.

  2. #2
    Join Date
    Feb 2016
    Posts
    149

    Default Re: Hull treatment: can you recommend someone in South?

    How olds the boat? Having done such a treatment to my 40 year old Brit-built cruiser i can safely say if i had my time again i'd never have bothered. Go buy Hugo Du Plessis' book on fibreglass boats, then if you're still worried about the blisters pop them open, sand back & fill with something like International Watertite and dont worry. The cost & time taken to do the job properly, and thats the key word - properly - isn't worth it not given secondhand values, just my opinion of course..................................

  3. #3
    Join Date
    Mar 2015
    Posts
    1,007

    Default Re: Hull treatment: can you recommend someone in South?

    Sorry, canít help with south coast suggestions but I would agree with the previous post. The boatyard I worked at charged £300 per foot length of boat to deal with osmosis. The boat that was in there being done when I was there is currently up for sale at £15k. His osmosis treatment came to £10k. Yikes!
    Last edited by fredrussell; 11-09-19 at 12:14.

  4. #4
    Join Date
    May 2001
    Posts
    15,571

    Default Re: Hull treatment: can you recommend someone in South?

    Quote Originally Posted by guardian View Post
    How olds the boat? Having done such a treatment to my 40 year old Brit-built cruiser i can safely say if i had my time again i'd never have bothered. Go buy Hugo Du Plessis' book on fibreglass boats, then if you're still worried about the blisters pop them open, sand back & fill with something like International Watertite and dont worry. The cost & time taken to do the job properly, and thats the key word - properly - isn't worth it not given secondhand values, just my opinion of course..................................
    I’d do exactly the same. Watertite is easy to apply, just make sure that after you’ve opened any blisters, you give them several good washes with fresh water. Counter intuitive, but you need to flush out the liquid that caused the blisters in the first place.

  5. #5
    Join Date
    Mar 2017
    Location
    Me; Nth County Dublin, Boat;Malahide
    Posts
    844

    Default Re: Hull treatment: can you recommend someone in South?

    Quote Originally Posted by guardian View Post
    How olds the boat? Having done such a treatment to my 40 year old Brit-built cruiser i can safely say if i had my time again i'd never have bothered. Go buy Hugo Du Plessis' book on fibreglass boats, then if you're still worried about the blisters pop them open, sand back & fill with something like International Watertite and dont worry. The cost & time taken to do the job properly, and thats the key word - properly - isn't worth it not given secondhand values, just my opinion of course..................................
    +1, but, after popping the blisters, scrape out any loose material, flush well with plenty of fresh water then allow to dry out well. When you are sure the substrate is reasonably dry, grind out any de-laminated material before filling with marine filler. Please note, I write not from personal experience but from what I have read on this forum.

  6. #6
    Join Date
    Mar 2015
    Location
    London
    Posts
    54

    Default Re: Hull treatment: can you recommend someone in South?

    The boat itself cost me just about 5k (although some similar boats cost around 10k), 40 year old, but I plan to spend a fair bit time with it, improve and eventually sell, not scrap - this is why I thought about doing something.
    To be precise, I don't even have blisters. There are some old dents - a dozen of slightly bigger ones (3mm diameter or so) and myriads or tiny dots (1mm and smaller). But they are dents, not blisters. Last winter I have applied a thick layer of antifoul to cover it up until this winter's maintenance, so the suggestion is just to sand it all all back, fill with some decent filler and paint it back again?

  7. #7
    Join Date
    Feb 2016
    Posts
    149

    Default Re: Hull treatment: can you recommend someone in South?

    Quote Originally Posted by Gedimin View Post
    The boat itself cost me just about 5k (although some similar boats cost around 10k), 40 year old, but I plan to spend a fair bit time with it, improve and eventually sell, not scrap - this is why I thought about doing something.
    To be precise, I don't even have blisters. There are some old dents - a dozen of slightly bigger ones (3mm diameter or so) and myriads or tiny dots (1mm and smaller). But they are dents, not blisters. Last winter I have applied a thick layer of antifoul to cover it up until this winter's maintenance, so the suggestion is just to sand it all all back, fill with some decent filler and paint it back again?
    Yeah i wouldn't worry fella, seriously get this book

    To give you some idea of cost, i spent around £2500 on materials including epoxy, bi-axial cloth & filler additives plus things like hand tools, power tools, building a shroud around the boat, a tramex hygrometer, power hot washer, 10 x IR heaters! and tons of ancillary stuff like disposable gloves, suits, paint rollers, brushes, trays plus a guy to come and peel the gel - seriously the list is endless. Then (another breath) theres the two years washing and heating the hull - my boat took just over a year to get it to budge off the maximum on the tramex scale.

    And from the advice i sort and paid for via several surveyors and the chemistry involved in the osmotic process; unless you get the boats hull down to a reasonable 'dryness' say the green to yellow scale on a tramex (40-50%) and most importantly you get the figures to stabilise which is what took the time on my boat plus 1000's of gallons of water daily hot-washing the hull to draw the solutes out you'd be wasting alot of time and money.

    Put it this way in one month running the IR heaters i ran up an electricity bill of £600 to put that in perspective my yearly electric bill for my property is around £1000 so be wary of any yard offering a cheap quick job for the work involved when done correctly is anything but. If i price up my time (2 years worth of evenings and weekends) and the above material costs i get a figure of around £12K for a boat that you can now buy for as little as £3K...................................
    Last edited by guardian; 11-09-19 at 15:32.

  8. #8
    Join Date
    Jul 2006
    Posts
    4,816

    Default Re: Hull treatment: can you recommend someone in South?

    Cautionary tale:

    Buyers of 33 ft 40 year old boat told moisture levels a bit high, though not a trace of blisters. As they wanted to keep it long-term they had it "osmosis treated" as a precautionary measure - full Monty, gelplane, epoxy filler, etc. all done by a well known boatyard. 10 years later they decided it was getting a bit too big for them in their 80s, and put it up for sale with us ( https://www.yachtsnet.co.uk/ ).

    Survey for new buyers reported something odd - when he scraped back antifoul he found his scraper was gouging the epoxy, which was the consistency of rather elderly Parmesan cheese rind, not a rock solid surface. Another surveyor reported the same thing. Boatyard that did the "osmosis treatment" not interested in even giving a discount on another gelplane, epoxy etc. even though it was clear that there was something horribly wrong with their work.

    Other yards then said the fix wold be even more expensive than the usual cost as the "cheesy epoxy" would clog a gelplane. We did sell the boat in the end, but at a huge discount to the asking price. The stupid thing was that if the hull had not developed blisters in 40 years it would have been unlikely to do so in the next ten years. The owners had paid £6000+ for a precautionary treatment that ended up costing them a lot more than £6,000 more on price reduction on sale.

    Others have recommended du Plessis' book - I agree completely. He says total gelcoat replacement should be an absolute last recourse, and that it should not be done based solely on moisture meter readings.

  9. #9
    Join Date
    Jun 2005
    Location
    Solent, UK
    Posts
    4,629

    Default Re: Hull treatment: can you recommend someone in South?

    I had a similar problem some 15 years ago. The problem was water ingress into voids in the hull. For example, Snark had an encapsulated keel. Either end of the encapsulated lead, the hull has filled with foam. Over 40 years the foam had got water in it and gradually turned to wet mush. Drilling into the hull enable gallons of water to flood out, We just plugged the holes after a sensible drying out period, The chainplates were inside GRP Boxes moulded into the hull. These were full of water too. You'd have thought a surveyor worth his salt (and the £280 he'd charged for the survey) would have known better. Mine wasn't even embarrassed enough by the discovery to offer a refund.
    Grow old disgracefully, it's more fun

  10. #10
    Join Date
    Jan 2012
    Location
    South Coast
    Posts
    5,196

    Default Re: Hull treatment: can you recommend someone in South?

    So you have no blisters on a 40 year old hull. That it has absorbed a small amount of moisture is hardly a surprise, so why consider either a plane of the gel which is 100% attached to the glass substrate, or worse smother the hull in epoxy trapping in a minor amounts of moisture.

    Professional treatment would likely wipe out the amount you have paid, and any serious future buyer would understand that osmosis in 40 year old hull is something of a myth as far as causing any real problem.

    If it were me (oh yes it is me !) I would be (I am !) finding something else to spend the money on.
    Interested in Corvettes PM me for details of the Corvette Motorboat Association

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