Strip paint inside hull for outside weld?

[hopalot]

I have 6 hairline cracks on the hull of a 92 quintrex fishmaster ranging from 1 inch to 3 inches long, half of these are new cracks and the others have become visible from the previous owners welding attempts at fixing them. The underneath hull is not painted but the inside hull is painted and harder to find the cracks. So my question is do i have to strip the paint inside the hull before i get a welder to fix the cracks or can he just weld them from the outer hull?

[madmackrel]

Mate when it comes to welding ally the cleaner you can get it the better the weld. Also ally will retain the heat more so than steel..... so if it was me id remove the paint.
Cheers MM

[astro66]

no need to remove the paint on the inside...it will just burn were the weld is...just make sure they cleanup the ally on the outside were they weld...
trouble is once you weld it weakens the metal and it usually cracks again unless you fix the reason you have so many crack to start with...

[hopalot]

Fairly new to the boating scene and only had this one for 6 months so not to sure what the reason could be. The cracks arent on any weld joins just out in open. The aluminium is a dull grey and the only way i can describe it as looks and feels like fur, a mate said the same thing. The previous owner said it was from a acid wash maybe?

[hopalot]

Just wanted to add that i only want to prep the areas to be welded to save some cash, any ideas on the proper way to prep before a welder can be called?

[Owen]

Remove the paint if you can get at it.
Any contaminants on the inside will migrate through when its welded, making it harder to weld as the contaminants have to come to the surface before the weld can fuse properly.
Don't stress if you can't get at it but the cleaner the joint the better.

[cormorant]

Let the welder do the prep if he is welding from the outside? Get him to tell you what he wants done.
Is it because it is where rollers from the trailer are in the wrong spots and it has been strapped down hard? Some happen with the way people drive on trailers. Different texture of a lot can be electrolosis if there has been swivels etc in th hull or battery / electricals earthing via teh hull. .