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  1. #21
    Join Date
    Jan 2003
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    Suffolk
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    3,062

    Default Re: Anti-fouling - Orwell Mooring

    You might want to consider an aluminium anode as well.

    Quote Originally Posted by Minn View Post
    I reckon you will be getting limescale on top of whatever you apply, as per the Deben, so I'd go for a soft one.

  2. #22
    Join Date
    May 2003
    Location
    Here or there
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    76,946

    Default Re: Anti-fouling - Orwell Mooring

    Quote Originally Posted by fredrussell View Post
    Well Im up at Debbages. I hadn't considered this before but It must be pretty brackish up there, at least half the day anyway during the ebbs, as the Gipping is flowing out straight past my beloved boat. Is this likely to be a good or bad thing re fouling?
    Did you know that Lord Haw Haw claimed the Germans had bombed Dagworth Dock
    Brexit: ‘taking back’ what we had never lost, in order to lose everything we had...

  3. #23
    Join Date
    Jun 2002
    Posts
    2,819

    Default Re: Anti-fouling - Orwell Mooring

    Various views here and interesting to hear Tradewinds comment on aluminium anodes - we have used them in salt and fresh and not just brackish and prefer them. That said I am wondering whether to g for zinc or Ali as we are moving from fresh to salt.

    Putting a different dimension on the anti-foul question, anyone gone for coppercoat and have any views on whether it is worth the expense?

  4. #24
    Join Date
    Sep 2014
    Posts
    273

    Default Re: Anti-fouling - Orwell Mooring

    Quote Originally Posted by Greg2 View Post
    Various views here and interesting to hear Tradewinds comment on aluminium anodes - we have used them in salt and fresh and not just brackish and prefer them. That said I am wondering whether to g for zinc or Ali as we are moving from fresh to salt.

    Putting a different dimension on the anti-foul question, anyone gone for coppercoat and have any views on whether it is worth the expense?
    Aluminium anode - yes in seawater and brackish water
    Antifoul - seajet shogun 33 - was on the Orwell half of last season, then Thames - hardy any growth
    Copper coat - if it's a new boat then yes as you can be sure it's dry. Old boat - only if you can be 100% sure it's dry as you don't want to lock moisture in. If any doubts then antifoul and regular keeping ashore over the winter to ensure it dries.

  5. #25
    Join Date
    Mar 2015
    Posts
    1,002

    Default Re: Anti-fouling - Orwell Mooring

    Quote Originally Posted by sailorman View Post
    Did you know that Lord Haw Haw claimed the Germans had bombed Dagworth Dock
    I'm afraid I haven't the foggiest what you mean!

  6. #26
    Join Date
    Jun 2002
    Posts
    2,819

    Default Re: Anti-fouling - Orwell Mooring

    Quote Originally Posted by STOL71 View Post
    Aluminium anode - yes in seawater and brackish water
    Antifoul - seajet shogun 33 - was on the Orwell half of last season, then Thames - hardy any growth
    Copper coat - if it's a new boat then yes as you can be sure it's dry. Old boat - only if you can be 100% sure it's dry as you don't want to lock moisture in. If any doubts then antifoul and regular keeping ashore over the winter to ensure it dries.
    Yes, I have some sympathy with the point about the epoxy locking moisture in but I have heard it said that whilst it may do just that it also prevents further moisture ingress whereas traditional anti-foul will not do anything to prevent further moisture ingress.

  7. #27
    Join Date
    Sep 2014
    Posts
    273

    Default Re: Anti-fouling - Orwell Mooring

    Quote Originally Posted by Greg2 View Post
    Yes, I have some sympathy with the point about the epoxy locking moisture in but I have heard it said that whilst it may do just that it also prevents further moisture ingress whereas traditional anti-foul will not do anything to prevent further moisture ingress.
    If the hull is wet as the majority of old boats are then you want to be able to see if blisters develop and take them out in situ. At the same time you want the anti antifouled hull to dry regularly when on the hard.
    Osmosis is a problem as much from the outside as it is with bad ventilation on the inside.
    If you were to seal a wet boat on the outside and osmosis does develop eventually then the osmosis will no longer be cosmetic below the gelcoat but deeper in the laminate.
    Therefore, I believe it not prudent to copper-coat an older boat or to buy a copper-coated boat that hasn’t firstly been copper-coated when it was still new.

  8. #28
    Join Date
    Aug 2005
    Location
    Brightlingsea, Essex
    Posts
    984

    Default Re: Anti-fouling - Orwell Mooring

    If moisture can get in to the GRP very slowly from the outside surface, can it not escape very slowly from the inside surface (assuming it's not a closed-cell foam sandwich)? Unless you lock it in with epoxy on both sides that is. Just a thought.

  9. #29
    Join Date
    Sep 2014
    Posts
    273

    Default Re: Anti-fouling - Orwell Mooring

    Quote Originally Posted by MikeBz View Post
    If moisture can get in to the GRP very slowly from the outside surface, can it not escape very slowly from the inside surface (assuming it's not a closed-cell foam sandwich)? Unless you lock it in with epoxy on both sides that is. Just a thought.
    Moisture doesn't simply travel through the hull and can be attracted from the inside and outside.
    The below is from Westsystem and explains the process in detail:
    Blisters occur when water that has penetrated the laminate dissolves water soluble materials within the laminate and accumulates in voids or cavities below the gelcoat layer. The solution of water and water soluble materials, through the process of osmosis, attracts more water to the cavities to try to dilute the solution. The pres- sure of the accumulating water enlarges the cavities to form gelcoat blisters.
    When water soluble materials in a polyester resin laminate mix with moisture that has pen- etrated the laminate, it creates an acidic fluid. This acidic mixture can attack the polyester resin throughout the laminate, severing the chemical bonds that hold the resin matrix to- gether, as well as the resin-to-fiber bonds. This process is known as hydrolysis. Once hydro- lysis has started in a polyester hull, the hull’s strength has been compromised and the potential for serious additional hydrolysis will never go away. If you own a fiberglass boat built with polyester resin, you should be aware that the potential for this problem exists. Gelcoat blisters can often be repaired before the laminate is damaged by hydrolysis. Keep in mind that gelcoat blisters can be an indicator of hydrolysis, and that hydrolysis can occur without the appearance of blisters. - hence my view of copper-coating.

  10. #30
    Join Date
    Aug 2005
    Location
    Brightlingsea, Essex
    Posts
    984

    Default Re: Anti-fouling - Orwell Mooring

    My thoughts were prompted by comments about the epoxy 'trapping' moisture in the laminate. For it to be permanently trapped you would have to permanent seal both sides. I'm not advocating epoxying a damp hull.

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