Bubbling paint on alloy boat
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Category: General Forums
Forum Name: The Boat Shed
Forum Description: Discuss all things boating.
URL: https://www.fishing.net.nz/forum/forum_posts.asp?TID=58761
Printed Date: 02 Feb 2026 at 6:31pm
Topic: Bubbling paint on alloy boat
Posted By: Smelly Buoy
Subject: Bubbling paint on alloy boat
Date Posted: 20 Oct 2010 at 7:50am
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Hi, hope someone can help me here. I have an alloy boat that has been painted topsides. It is 11 years old, and in some places, I have noticed that the paint is bubbling, generally over a large area, but without any apparent cracking. Aesthetically, I can live with it. But my real concern is, is this a sign of some galvanic corrosion going on under the paint? And should I be removing the paint and treating the metal beneath asap? Cheers, Woody ------------- Tangled Up In Blue "Veni, Vidi, Velcro" I came; I saw; I stuck around. |
Replies:
Posted By: Ronblue
Date Posted: 20 Oct 2010 at 8:08am
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I've got very little experience but I've seen that before and it was corrosion. Moisture gets trap between paint and aluminium as aluminium is actually (to a certain extend) porous (believe it or not)... It's also frequent near bolts and fittings I would get rid of the paint where it's happening and deal with the issue asap. But then again, I may be wrong here.  good luck |
Posted By: Wide Load
Date Posted: 20 Oct 2010 at 8:29am
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Can you post pics? |
Posted By: Catchelot
Date Posted: 20 Oct 2010 at 8:44am
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Is the problem areas close to stainless steel fittings, nuts and bolts, etc?
If so a bit of electrolysis is happenning with dis-similiar metals, as ali does not like stainless and those fittings should be isolated from the hull with things like rubber washers, gaskets and heat shrink over bolt threads, etc... ------------- "The sea, once it casts its spell, holds one in its net of wonder forever." - Jacques Cousteau |
Posted By: tobez
Date Posted: 20 Oct 2010 at 9:23am
| thats whats happening - a product called duralac will help that |
Posted By: one leg
Date Posted: 20 Oct 2010 at 10:05am
------------- woman who say they are equal to men ,show lack of Ambition . |
Cachelot wrote:Posted By: Smelly Buoy
Date Posted: 20 Oct 2010 at 10:07am
Will do ------------- Tangled Up In Blue "Veni, Vidi, Velcro" I came; I saw; I stuck around. |
Posted By: johnybegood
Date Posted: 20 Oct 2010 at 10:51am
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Got the same problem on our boat. All the raised paint bubbles are around either dome clips or canopy clips. Must be SS screws, thanks Smelly Buoy for asking the Q as it's helped me too. got some pics of ours here too. thanks |
Posted By: johnybegood
Date Posted: 20 Oct 2010 at 10:57am
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Posted By: Smelly Buoy
Date Posted: 20 Oct 2010 at 10:58am
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Hmm, from my recollection, my bubbles were even present away from penetrations and fittings. Will check it out. Have emailed the manufacturer too. ------------- Tangled Up In Blue "Veni, Vidi, Velcro" I came; I saw; I stuck around. |
Posted By: Busted!
Date Posted: 20 Oct 2010 at 1:45pm
| Paint doesn't like sticking to ali. Moisture penetrates the paint and lifts the layer and causes surface corrosion. Different to electrolysis, but same effect at the end of the day. 11 years isn't a bad whack really, probably about due for a rub back and respray! |
Posted By: Wide Load
Date Posted: 20 Oct 2010 at 2:25pm
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I'd peel off a blistered section (take pics as you go) If it's corroding (powdery white substance if dry, jelly-like if wet) then you'll need to remove the paint (soda blast?) and decide if you want to paint again. |
Posted By: Smelly Buoy
Date Posted: 20 Oct 2010 at 2:32pm
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Thanks Red. Interestingly, the boat's top-sides are white,and the hull is dark green topped with Nylac. It is the white that is blistering, the Nylacked area seems ok - thus far. ------------- Tangled Up In Blue "Veni, Vidi, Velcro" I came; I saw; I stuck around. |
Posted By: Busted!
Date Posted: 20 Oct 2010 at 5:56pm
| There will probably be small areas of crap under the green. What is the inside nooks and crannies of the hull and bilges like? Out of sight out of mind!!! |
Posted By: Smelly Buoy
Date Posted: 20 Oct 2010 at 6:08pm
Pretty good on the bare surfaces ------------- Tangled Up In Blue "Veni, Vidi, Velcro" I came; I saw; I stuck around. |
Posted By: blackboat
Date Posted: 20 Oct 2010 at 6:37pm
| insulate all screws, bolts etc as the two different metals react ,,,bought a brand spanking new stabi couple yrs back and the paint reacted where the anchor fairlead was bolted on ,add to the fact that water then gets in there and you got a disprin |
Posted By: Kings Marine
Date Posted: 21 Oct 2010 at 3:21pm
Ah yes - bubbling paint on alloy boats. The short answer is not to paint a alloy boat...... dissimilar metals (i.e. sst / brass & steel on alloy) will make short work of any paint. even as the photo shows an alloy rivet in a plastic canopy lug will also start the paint bubbling, and areas where there appears to be no fittings or anything will also bubble and corrode eventually. One way to get good results is obviously the paint prep, including the type of filler/fairing product used, also try to drill all the holes required in boat (dash holes-light fittings-sw panels-rod holders- etc etc) and then paint boat, then fit accs. The reason for this is, if you get any area where salt water can get in underneath the paint it will start to bubble ------------- The Mighty Waikato http://www.facebook.com/pages/Kings-Marine/100476476662857?%3Fref=ts |
Posted By: Hurf
Date Posted: 21 Oct 2010 at 8:14pm
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I heard that the ali sucks up water and this can lead to that same problem. Some boat makers bake the boat befor painting to dry it out. ------------- THE FLOGGINGS WILL CONTINUE UNTIL MORAL IMPROVES. |
Posted By: Hamish_S
Date Posted: 29 Oct 2010 at 3:31pm
| So what to do? I have the same problem but I cannto find what to do... How much does it cost to repaint an 18ft boat? |
Posted By: back2black
Date Posted: 29 Oct 2010 at 3:36pm
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Soda Blast, prep and repaint! Google up NZ Sodablast as this is the best way to remove the bubbles without any damage to the surface or rubber/plastic bits ------------- Auckland Blasting Services Ltd Multi Media Blasting - Automotive/Marine/industrial/Residential Ph: 0225278968 ( 02BLASTYOU ) |
Posted By: Smelly Buoy
Date Posted: 29 Oct 2010 at 5:54pm
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Hmm, found this. http://www.garagenight.tv/diy-soda-blasting-build-your-own-rig-cheap/ Feel a project coming on. ------------- Tangled Up In Blue "Veni, Vidi, Velcro" I came; I saw; I stuck around. |
Posted By: Brooook
Date Posted: 29 Oct 2010 at 8:46pm
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Paint starting to go on our 80s alloy boat. Can't be bothered painting the old girl - just happy that it is a solid reliable boat in the water and who cares what it looks like on the boat ramp.
 ------------- Give a man a fish and he will eat for a day.............Teach a man to fish and he will sit in a boat all day drinking beer, |
Posted By: Hamish_S
Date Posted: 30 Oct 2010 at 10:10am
| So is whats happening to our boats, purely cosmetic or is it harming the hull it self? If its just cosmetic ill leave it unitl it gets really bad and redo the whole boat, or maybe just bring it back to a natuaral alloy finish.. if its harming the boat then Ill do somthing about it, i have bubbling paint in quite a few places on my boat... |