The objective is to just spot weld initially and then short runs to join it up so it is inevitably slow as you do not want too much heat in one spot causing distortion. I do not have the skill level yet to join less than 3mm thick reliably. If the joint is properly set up it ends up a nice result. These parts are not highly stressed so I doubt that fatigue will be a problem in my lifetime. For brackets and fittings using 3mm and thicker I am finding TIG welding gives a nice result. The chosen method depends on the material and the skill level. He won the bet but it took him more than an hour of tedious spot welding and cooling. I think hand welding with less than 3mm material is a real challenge unless the individual is highly practised - my nephew was challenged to cut the tops off two coke cans and join them. I have rivetted it, glued it, rivettered/caulked, screwed/caulked, 'brazed' and I am finally able to weld it properly. It has its difficulties and there are a few tricks. I find aluminium a very nice material to work with. In a production environment (though I do not like them much) they are still a viable and economical manufacturing process. Most people are surprised to learn that rivets are pretty fatigue resistant because the metal around the rivet hole is in compression (caused when the deforming rivet expands in the hold and compressing the metal around the hole). Yes corrosion starts at the rivet holes, but fatigue cracks can initiate in welds, as well as corrosion. When aluminum aircraft structures are riveted they use sealant between all of the surfaces, and in the rivet holes. However it so badly degraded it was just determined it was not worth fixing. And though it had be rebuilt and refitted several times, much of the original riveted steel hull was still present. It had served Puget sound daily for over seventy years up until just before the Thanksgiving day weekend in November. The oldest auto ferry in the USA was just retired from Washington state waters, it was built in 1927 and used riveted hulls.

Riveted vs welded jon boat