Aluboat, grind and polish weldings

[Jasper_ghost]

I have some theories about minimizing the welding width, means carefully TIG weldings or alternatively MIG followed by grinding and polishing of weldings below the waterline. I think the result is better performance, but does any have experience here. It will take a lot of time so any experiences if it is the effort worth or should I just polish or leave it in raw aluminium.
By the way, it is for a fast planning hull.

[messabout]

Grind and polish only if you have a racing hull in mind. No doubt that weld beads will cause some drag but for a general purpose boat, grinding is questionable idea. If you have a lot of transverse seams there is obviously more influence. If the seams are mainly longitudinal, the effect on performance will be small and not worth the labor and the risk of bead failure. The location of transvese seams is perhaps worthy of some thought. A planing boat may not even have the beads wet when it is in full flight. Consider using some sort of filler putty for the longitudinal seams. Rather than removing the seams, build them up a bit so that they are smooth ridges. That may even help keep some of the spray down.

[mydauphin]

Most AL Boats for speed are faired with epoxy and sanded to slick finish. It adds a little weight but maintains strength. As messabout mentioned above be careful of sanding welds, too much work to do it right. And remember AL can crack along weld sometimes if weld is not perfect. I usually weld a T on inside and outside.