Filler for Aluminium Hull (Below Waterline)

Colleagues
I am coming nearly to the end of quite a lot of hull repairs I have done on a aluminium hull rebuild. They were originally corrosion spots were I ended cutting them out and welding in new plates or drilling and filling with weld were allowed.
Due to my finishing techniques being many a flap sander on a 5" grinder I have ended up with a surface that is no were near perfect, or far from it, Also the heat from welding has produced a few depressions on the plates.
My question is there a body filler that is acceptable to be used on the underside or bellow waterline on the aluminium hull?
Thanks

 

If a few blows from a carefully placed hammer cant straighten it I think I would leave it.

 

Frosty
Biggest Problem is we don't have access to the bottom plates through the boat, the deck is fully welded in and I was not prepared to remove it, All repairs were done from the outside.
Thanks

 

If its under the water line in antifoul its your choice. Filling will do nothing but potentially come off.

 

International Interprotect epoxy primer... then epoxy fairing compound... then Interprotect primer, then antifoul is what I use.

Sandblasted aluminum is best...

 

The boat is trailerd, no real need for anti foul, your second point is the one I'm worried about, if it starts too lift its going to be corrosion city.

michael pierzga
Have you ever had it cracking or lifting, I was thinking with movement in the hull it may de-laminate? Just a point on sandblasting, I have also being told never sandblast an aluminum hull as it contaminates it.

Thanks Again

 

Ah --if its trailerd then its not a thick hull and will flex as it is supported by trailer rollers.

I would not waste 40 50 quid on filler that is likely to come off

 

Hi friends i watch out all your post and now i want to share my opinion with you my friends that.
You probably have a serious corrosion issue and these pinholes are the first sign of incipient failure you can use temporary repairs which may well work in the short term but will only leave a larger issue in the future.
Thanks.

 

All the above comments are true, do not just slap some filler without fixing underlying problem. As far as filler... an epoxy filler of course.

 

Gentlmen
Thanks for the replies, and yes you're 100% correct on what you have said. Except the question was asked not to fill holes but to be used patch dents and marks in the plates to achieve a flat surface, like car body filler. All the corrosion areas have being removed and replaced with new plate, but some grind marks and heat dents remain.
Cheers

 

fair up lowspots ,fill scratches,dints,holes above waterline. using epoxy resin or polyester resin. rough up surface for better adhesion , use150 grit sand disc or finer.sand epoxy filler down to smooth out or shape the filler. prime and paint or anti foul below waterline. resins expand and contract at same rate as aluminium

 

You can hammer dints out like a car. I would not use filler underwater and begs to ask Why you need to?

 

Dont forget, you can use a suction approach with glaziers pad. Fasten on and use levers to pull out what you can.

 

it is not a motor vehicle, i fail to see the comparison. is it possible to pressurize the hull and pop the dents out.

 

will never work, you can not use a glaziers pad. don't you understand glass is not aluminium.