RichardN Posted November 24, 2014 Report Share Posted November 24, 2014 (edited) That Debdale page rang a very distant alarm bell with me. See http://www.vmzinc-us.com/zinc-basics/compatibilities.html I understood that bitumen can have a damaging reaction with Zinc. I suspect a paint on product like Zinga or Galvafroid will have most of the zinc sufficiently barrierd by the dried carrier "paint" but there is no barrier if the hull has been hot galvanised. I don't know enough about the subject to do more than give this pointer but if it were my boat I would not risk a bitumen product and go for epoxy. That site is strange, I know it looks like it is written looking at zinc sheeting but still strange when it states that * "zinc in contact with mild steel is not desirable". Well yes the zinc will sacrificially corrode, that's why we use zinc galvanising. Pretty desirable to me to have a longer life to first maintenance by galvanizing things. Charts available for corrosion rates on the galvanizers association website. * Cement etc is an unacceptable corrosion product. Well mortar or concrete will etch galvanizing a bit when wet but that reaction stops as soon as the concrete or mortar has set. * The bit about bitumen contact is strange. One of the standard construction specifications is to coat with bitumen columns in cavities or where they may get some bimetallic corrosion, that specification has been used to my knowledge for decades without a problem. There are plenty of good references to corrosion control, The Galvanizers Association is very good, the National Physics Laboratory does some good stuff, excellent on bimetallic corrosion and fasteners in timber, there is an encyclopaedia style site on steel set up by the some of the key UK players here http://www.steelconstruction.info/ I should add that the Galvanisers Association don't like zinga, they used to recommend Zinga or Metaflux or any of the really high zinc content coatings but I think they got a bit upset by some marketing from Zinga suggesting that Zinga is better than galvanising. Galvafroid has a lower zinc content. Our boat is zinga-ed, it is a great product. The blue bits on the boat are single pack paint, the blacking is 2 pack sprayed on so yes you can put 2 pack on Zinga. Next time we will make sure it has time to harden before we go up the Chesterfield Canal. I have seen molten zinc spray on things too awkward to galvanize, mainly things with asymmetric geometry. Seems to work well, well at least something done in the mid 90s had not rusted last time I saw it. Not sure you could do it on a boat? In response to the query about painting the baseplate here is a photo of ours after 5 years. A bit of surface rust, nothing of any note. Edited November 24, 2014 by RichardN Link to comment Share on other sites More sharing options...
cuthound Posted November 25, 2014 Report Share Posted November 25, 2014 Our boat is zinga-ed, it is a great product. The blue bits on the boat are single pack paint, the blacking is 2 pack sprayed on so yes you can put 2 pack on Zinga. Next time we will make sure it has time to harden before we go up the Chesterfield. Thanks Richard, next time my boat needs blacking I will get it done in 2 pack, over the Zinga. Link to comment Share on other sites More sharing options...
cuthound Posted November 25, 2014 Report Share Posted November 25, 2014 I too have read that bitumen is not compatible with zinc but I suspect this is based on the common misconception that oil based products generally react with galvanised surfaces. As far as I am aware, and I'll happily give way to someone who has better knowledge of chemistry, zinc does not react in any way with oil/petroleum. This is not to say that something else in an oil based product will not cause a reaction though. I have had direct experience of someone specifying galvanised steel pipes in the fuel system of a standby generator system. The galvaising on the inside of the pipe came away from the mild steel and blocked the fuel filters. Presumably because the diesel fuel interacted with it. Link to comment Share on other sites More sharing options...
Neil2 Posted November 25, 2014 Report Share Posted November 25, 2014 I have had direct experience of someone specifying galvanised steel pipes in the fuel system of a standby generator system. The galvaising on the inside of the pipe came away from the mild steel and blocked the fuel filters. Presumably because the diesel fuel interacted with it. I believe there's a school of thought that it's the sulphur in diesel that causes this. Link to comment Share on other sites More sharing options...
cuthound Posted November 25, 2014 Report Share Posted November 25, 2014 Could be, it was in the mid 1980's, when I worked for BT and some of their red diesel was very old (large tanks & little running of generators), so oldcdiesel with very high sulphur content (up to 5% IIRC). Anyway resulted in specification change to prohibit any galvanising of fuel system components. Link to comment Share on other sites More sharing options...
247 Posted July 9, 2020 Report Share Posted July 9, 2020 On 24/11/2014 at 10:38, b0atman said: I have had my boat done at Debdale In April also had the epoxy finish plus anodes fitted . looks an excellent job .Time will tell . Only thing is have still not had any Guarantee paperwork when I contacted them in September answer was Mike is still working on it ? there was no mention of any free checks at 5 years . Hi B0atman, Im considering having my boat zinc sprayed at Debdale. Just wondering how your hull went on after this process and what it is like 6yrs down the line? I'd welcome an update from you. Thanks. Link to comment Share on other sites More sharing options...
wandering snail Posted August 29, 2020 Report Share Posted August 29, 2020 On 09/07/2020 at 22:52, 247 said: Hi B0atman, Im considering having my boat zinc sprayed at Debdale. Just wondering how your hull went on after this process and what it is like 6yrs down the line? I'd welcome an update from you. Thanks. We too. Would it survive the Shroppie shelf or lock scraping? Link to comment Share on other sites More sharing options...
Alan de Enfield Posted August 29, 2020 Report Share Posted August 29, 2020 On 09/07/2020 at 22:52, 247 said: Hi B0atman, Im considering having my boat zinc sprayed at Debdale. Just wondering how your hull went on after this process and what it is like 6yrs down the line? I'd welcome an update from you. Thanks. 1 hour ago, wandering snail said: We too. Would it survive the Shroppie shelf or lock scraping? I'm not sure you'll get an answer, this is a 6 year old thread, and Boatman has not been on the forum for the last 12 months, Link to comment Share on other sites More sharing options...
TheBiscuits Posted August 31, 2020 Report Share Posted August 31, 2020 @peterboat has got Zings on his boat, and is pleased with it. Hopefully he will be able to answer your questions. I'm not sure if Debdale did his, but I've only heard good reports about their Zinga services. Usually followed by a grimace about the cost ... Link to comment Share on other sites More sharing options...
Phil Ambrose Posted August 31, 2020 Report Share Posted August 31, 2020 A lot has happened in my life since I posted on this thread in 2014 (post 20) and I was forced to sell my boat (health of my wife) The boat was a Colecraft built in 1981 and was cold galvanised, the buyer had a survey and the surveyor said it had the best hull he had ever seen. Says something about the process. Phil Link to comment Share on other sites More sharing options...
247 Posted Tuesday at 19:33 Report Share Posted Tuesday at 19:33 Had my boat grit blasted, pit welded, zinc sprayed and 2-packed in 2021 at Debdale. Took it out of the water 3 years later after many locks and miles, but v little time in a marina. All looking good underneath still, so can recommend Debdale for this procedure. It’s been great not to have to do the blacking, as it’s v physical and I’m not sure I’m up to doing it any more. 1 Link to comment Share on other sites More sharing options...
sigsegv Posted Tuesday at 19:53 Report Share Posted Tuesday at 19:53 (edited) 20 minutes ago, 247 said: Had my boat grit blasted, pit welded, zinc sprayed and 2-packed in 2021 at Debdale. Took it out of the water 3 years later after many locks and miles, but v little time in a marina. All looking good underneath still, so can recommend Debdale for this procedure. It’s been great not to have to do the blacking, as it’s v physical and I’m not sure I’m up to doing it any more. Excellent, having this done later (also at Debdale) this year so it's good to hear a success story! Edited Tuesday at 19:54 by sigsegv Link to comment Share on other sites More sharing options...
DandV Posted Tuesday at 21:20 Report Share Posted Tuesday at 21:20 Over coating the zinc with a high integrity coating system reduces the exposed sacrificial zinc surface, thus prolonging it's life. For inland waterway use magnesium is the preferred anode material because of its even greater reactivity. So adding easily replaceable magnesium anodes, even further reduces the work that the zinc surface has to do in suppressing corrosion of the, all important steel. The corrosion preference becomes: Magnesium first Zinz second. Steel last. The offshore oil industry added a huge amount of knowledge marine protective coatings practice, as the coating life very largely determined the safe life of these very considerable structures with massive contingent liabilities. Link to comment Share on other sites More sharing options...
john.k Posted Tuesday at 23:27 Report Share Posted Tuesday at 23:27 Five different kinds of zinc coating..........hot dip ,arcspray ,inorganic zinc ,epoxy zinc ,zinc paint ...............effective in that order. Link to comment Share on other sites More sharing options...
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