Great! Thanks for the positive replys and advise!
nds1968- Exactly, the cold start at the beginning and overheat at the end was my difficulties.
Hottrucks- damn, I didn't think of the copper! I've been using copper backers when welding thin auto-body panels for years.
Number 98 and others- I use a stainless brush and have been trying to keep things clean. Also, great tip on the wire, I'll heed that advise.
I burned up a bunch of wire practicing and with your tips have had favorable results. I invited an acquaintenance with some experience over to the shop and he gave me an ok on my welds. I guess I was expecting steel-MIG results or TIG looks and that's just not as probable with my set-up on alum.
Now here is a couple of "explainer" pics.
This project entails a tunnel in the hull and the purpose of the added transom height is to align the outboard jet foot at the top of the tunnel. I run shallow water and props are a no-go.
There will be two additional 2"x2" box-tube braces that run from the transom to gussets added to the floor ribs. Plus all will get re-bolted at the factory locations. The inner part (under the cap) is sandwiched marine plywood glued and screwed.
Thanks again.