alnuminium boat

duckman!!

What's the best way to fix cracks in an alnuminium boat?
When I've googled it they all use the alnuminium brazing rod and melt
It with a torch, is this the best way or have ye any other ways of doing it?

Also will marine paint stick to the alnuminium or do I need a special kind of paint?
Thanks!!

fergal.b

You have a few options Brazing,tig welding,epoxy "jb weld" or replete over it. As for painting you do need an clean finish "vapour blasting works well" then an etch primer and then paint.





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duckman!!

fergal.b wrote: »

You have a few options Brazing,tig welding,epoxy "jb weld" or replete over it. As for painting you do need an clean finish "vapour blasting works well" then an etch primer and then paint..

vapour blasting.... Sounds expensive! This is a cheap boat, I don't want
to spend to much on it!!

fergal.b

duckman!! wrote: »

vapour blasting.... Sounds expensive! This is a cheap boat, I don't want
to spend to much on it!!

Just leave it as it is then the etching primer can also cost a few quid, or you could try something like Hammerite it might work for a while.




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Bio Mech

fergal.b wrote: »

Just leave it as it is then the etching primer can also cost a few quid, or you could try something like Hammerite it might work for a while.




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I agree. How good a job you can do will depend on how much you want to spend on it. Are the cracks leaking? Are they close to rivets? if its just surface cracking an aluminium primer and some toplac will suffice for a while

pedroeibar1

fergal.b wrote: »

Just leave it as it is then the etching primer can also cost a few quid, or you could try something like Hammerite it might work for a while..

I doubt that Hammerite would last, despite its claims of no need for an undercoat. H will flake off galvinized iron (gates/railings) within a year or so if the surface is not correctly primed.

duckman!!

Bio Mech wrote: »

I agree. How good a job you can do will depend on how much you want to spend on it. Are the cracks leaking? Are they close to rivets? if its just surface cracking an aluminium primer and some toplac will suffice for a while

The crack is about 3 inchs long and it's in the aluminium you can see through it (slightly).This boat was never painted it was just bare metal, I need it painted a dark green for hunting!!
I have a marine paint I used on my fishing boat, I painted it straight onto the fibreglass and it held up very good, so I might try that!

fergal.b

If you scratch or sand the surface of the aluminium it will start to rust "oxide" within half an hour and the paint will flake off so if you are not going to use the etching primer don't prep the boat just paint in on, it still may not last but at least your aluminium will be ok.



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duckman!!

fergal.b wrote: »

If you scratch or sand the surface of the aluminium it will start to rust "oxide" within half an hour and the paint will flake off so if you are not going to use the etching primer don't prep the boat just paint in on, it still may not last but at least your aluminium will be ok.



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Then how come other aluminium boats I know of have bad dents and scratches and haven't rusted?? How's that different from a light sanding

Bio Mech

duckman!! wrote: »

Then how come other aluminium boats I know of have bad dents and scratches and haven't rusted?? How's that different from a light sanding

Its not like iron rust. Its surface oxidation similar to what you see with freshly cut lead. It doesn't propagate within the metal.

Try it and you will see the difference. Primer is the way to do a decent job. If you smooth it down only it will flake off much more quickly.

pedroeibar1

duckman!! wrote: »

Then how come other aluminium boats I know of have bad dents and scratches and haven't rusted?? How's that different from a light sanding

What you are calling 'rust' is more correctly 'oxidization', a process whereby the outer layer of a metal reacts with its surroundings to produce a 'salt'. Gun barrels are deliberately 'rusted' in a particular fashion (a process called 'blueing') to prevent rust damage, aluminium (boats, windows, aeroplane bits) undergo a similar process called anodization (scroll down a bit for aluminium) to prevent the formation of aluminium oxides.

Those boats that have deep scratches will have damaged the anodized layer and actually are oxidizing, which can lead to a scratch becoming what loos like a crack. If you are going to paint, use a primer.

duckman!!

So say if I sand it, primer it and paint it and then I go hit the boat of rocks(will happen) and the paint and
primer scratch off what can I do about that?
Would I have to touch it up straight away to stop it oxidising?

I'm just asking this as where the boat will be used is very rocky and every time it go out I nearly always hit some rock!
I use the boat only in fresh water if that makes a difference!!!