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Old 20-12-2010, 00:07   #1
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Restoring an Aluminum Dinghy

i have just purchased a 10ft aluminum dinghy,it is unpainted and in pretty good condition.it has no corrosion holes but the outside of the hull has gone very dull and has white spots all over which i guess is the start of some type of corrosion.what i want to do is clean the hull and apply a clear finish to seal and protect it.i do not want to colour paint it.
i was thinking of the following :
1.manual wire brush the whole hull
2.sand the whole hull with fine sand paper
3.hose down with fresh water
3.seal with a suitable clear product

any advice would be greatly appreciated
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Old 20-12-2010, 02:16   #2
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I think you would be better to clean and leave it in a unfinished state. A sealer is going to be difficult to maintain on a dingy. There should not be any corrosion problems, although sometimes dinghies are not made from aluminium grades suitable for the marine environment. Sealing it will not help any corrosion problems.
If you want to antifoul thats a different matter you need an epoxy barrier coat and a suitable anifouling for aluminium
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Old 20-12-2010, 03:09   #3
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thks for that noelex,it is a very solid oz made dinghy so there should not be a corrosion prob.i certainly am not going to apply something that is a maintanence prob.i have heard of people rubbing in car wax/polish after cleaning,is there an issue with that ? will it effect the aluminum ?
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Old 20-12-2010, 05:56   #4
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Be prepared to jump through hoops to legally register it, check it thoroughly for an ID plate or any numbers on it and have the local marine police run it past the data base on their computer. If you don't register it, you will cause even more trouble for yourself.
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Old 20-12-2010, 06:06   #5
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Originally Posted by lorenzo b View Post
Be prepared to jump through hoops to legally register it, check it thoroughly for an ID plate or any numbers on it and have the local marine police run it past the data base on their computer. If you don't register it, you will cause even more trouble for yourself.
Why so emphatic?--jus' curious.
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Old 20-12-2010, 06:23   #6
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phospheric acid or ospho works well for cleaning up alloy,wash off with water after.
the white spots are aluminium oxide,perfectly normal,wouldnt coat topsides with anything as marine grade alloy is resistant to corrosion, paint only makes surfaces anodic when scratched.

if you must paint etch coat,then epoxy,then tin based antifouling.

you can wire brush it but use a stainless brush as steel or brass bristles can cause problems,wouldnt use sand paper as you wont get a uniform finish,have fun,my dingy is 63 ft of aluminium............
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Old 20-12-2010, 06:30   #7
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what are you on about lorenzo b ???? register what ??? have you replied to the wrong thread ?? i asked for restoration advice !!
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Old 20-12-2010, 08:07   #8
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The general assumption by marine police is that a dinghy that lacks registration may have been stolen and the way to deter theft of boats is to make sure all boats are properly registered. I restored a lovely aluminum boat in Louisiana a year ago and had a nightmare of a time registering it. I'm only trying to be helpful.
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Old 20-12-2010, 08:34   #9
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yes thanks for your advice lorenzo b but why assume i live in the u.s. !!! this is exactly the reason why i live in asia, minimal to non existant regulation !!!!!
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Old 20-12-2010, 11:24   #10
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thks for that noelex,it is a very solid oz made dinghy so there should not be a corrosion prob.i certainly am not going to apply something that is a maintanence prob.i have heard of people rubbing in car wax/polish after cleaning,is there an issue with that ? will it effect the aluminum ?
Aluminium maintains is corrosion free state only in the presence of oxygen. If exclude oxygen you need to seal out moisture.
The danger with any treatment like wax or polish is that you can seal out oxygen but have moisture trapped on enter.
The other potential problem if that if you seal the hull everywhere, but one tiny spot, say a scratch in the wax, in certain circumstances that spot can corrode (It becomes a bit like an anode would be). Finally aluminium needs to be in a reasonably PH neutral environment not to corrode, if the polish or wax does not maintain this you will have problems.

You need to be particularly careful with dingys as they are often pressed out of aluminium that is too thin to weld so repairing is often impossible.

Having said all of that you are very unlikely to get any problems with car wax, but it sounds like you want to preserve the dingy and the best treatment is no treatment.

People are used to materials like steel and wood where it is important to seal out seawater. Aluminium is not like that you can suspend some marine grade aluminium completely untreated in seawater and it will not have any corrosion.
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Old 20-12-2010, 12:13   #11
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thanks for that noelex 77, i am glad i asked. i think i will just give it a soft rub with a wire brush to remove the aluminium oxide on it and leave it at that
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Old 20-12-2010, 13:33   #12
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Lucky you, it truly is beautiful in Asia. Enjoy.
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Old 23-12-2010, 21:30   #13
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hi sorry dint see the msg.
basically give a light brush down,then paint on acid solution,leave untill metal becomes bright,then wash down with lots of fresh water,repeat with brushing and acid on areas where there is a lot of discolouration.
may also be a good idea to use an engine cleaner detergent first to remove any grease.
through brushing afterwards this process will give a bright shiny finish,can also use plastic kitchen scourers,for difficult to reach areas.
have fun
seasons greetings and enjoy koh lipi,last time we ware there was during the tsunami in kho lanta,that we missed by 30 mins after upping anchor.
remington and jojo and rthymstick are friends of ours in phuket if you know them,
alex
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