Paint blistering repair or renovation ?

[StuWard]

Hi All,

 

I'm a new member that bought a boat second hand just before Christmas. 

We are loving her and all the fun she has given us thus far. 

As expected when you buy a pre-loved boat, they come with some bangs and scrapes.

I'm lookin for advise on how to get her looking a bit tidier over time. 

I'm in no rush because it is all just cosmetic. 

I have attached a couple of photos to show what has happened to her over the years.

Looks like blistering of paintwork as salt has gotten under it. 

Probably reels banging onto the gunwales when being placed in the rod holders etc. 

Also some paint peeling around when hooks have been fitted. This is probably corrosion due to different alloys in contact with one another. 

 

 

To tidy her up, are there any surface preps available and then repaint ? or are there surface coverings that just be placed over the paintwork ?

Edited March 27, 2021 by StuWard

[Welster]

The curse of a painted aluminium boat its frustrating.

Other than touch ups its a strip back and repaint I think.   Then fit all fittings with care.  Try to avoid self tapping screws that damage the paint edge.  Use nylon bolt and nuts where possible or nylon sleeves with stainless fixings.  If unavoidable use Tefgel when reinstalling the fitting.  On things like rod holders use sikka under them when reinstalling to seal it.  If repainting id use seam sealer to stop the salt getting into the seams.

 

After doing all that it will minimise it and slow it down but it will still recur over time.

 

[Fab1]

Hi mate,

   that's the reason I own a unpainted ally boat.Looking at that boats paint and bimini/canopy frame the previous owner/s didn't have a very good wash or maintenance schedule.

  To fix it properly that paintwork needs stripping right back down to bare/clean alloy then repainting.

If it was mine and funds were available I'd remove all fittings down to a bare hull.

I'd grind/Sand the corrosion until I got to bare alloy and clean paintwork.Then feather the edges of the clean paintwork.Seal the whole hull with sealer,etch prime the bare alloy areas,prime and paint with a good quality 2 Pac paint.

 Do what @Welster said sealing everything that is bolted/riveted on using his methods or a combination of those and duralac.

  You can buy thin rolls of sheet rubber from places like Clark rubber to make up gaskets for underneath fittings like rod holders,eyelets etc.

The weakest part of any paintwork is the edges of holes,body lines as paint is always thinner there due to the sharp edge and gravity when applying the paint.

As @Welsterpointed out paint is easily chiped on the edges of holes.

  Here's an easy way to prevent it using Teflon tape aka plumbers tape I've used for decades to avoid it.

Have you got any pics of whole boat?Good luck with it.

[hucho hucho]

I agree with everything what was said above, but I would do it slowly one step a time. Remove all the fittings then use the paint stripper, wire brush and sand paper. I would then clean it with the methylated spirits or mineral turpentine. After this I would reinstall the fittings and I would use the boat for 6-12 months to see what is happening with the aluminium and then decide about painting. Aluminium boat doesn’t need any paint protection.

cheers

[noelm]

Before painting it needs to be cleaned and primed with etch primer, then sprayed with quality paint (probably never match colour) then all fittings refitted using a proprietary insulation product (Duralac, Tefgel) and hope for the best.

[antonywardle]

I think if you are using a wire brush that it needs to be stainless wire brush

 

Unless I'm getting it mixed up with welding

[campr]

Under paint bubbling is caused by electrolysis.   I was told by a member of my fishing club who is a retired metalurgist that the heat caused by grinding, cutting and drilling aluminium is enough to change the composition of the metal so you can create a dissimilar metal enough to cause electrlysis.  Interesting but nothing you can do about it other than go slowly when using power tools to reduce heat buildup and reduce problem.  

I would also be wary of using rubber gaskets.  Plenty of people do but keep an eye on them if you do.  The original Quintrex boats were a subsiduary of Alcoa Aluminium and were discontinued due to the rubber strip between bottom strakes and the hull skin.  After many years the rubber supplier they used changed the formula of the rubber (including more carbon I think) and over the next few years hundreds of boats developed pin holes in the hull from electrolysis between the rubber and the hull and began to leak.  For about 3 years quintrex operated in the red as they recalled and repaired these boats.  I have heard rumours that it cost about $1 million to fix.   Ron