OK I'll buck the trend of my two buddies above, and love them both, but think the Miller you looked at will probably do over 95% of the 'steel' welding you will do. I've build trailers, all of what I have accomplished with the lakester and other projects with a Miller 175 or 180 can't remember and I'm not home.
The only thing I didn't do was the final weld on the front axles...
... I tacked them and then took them to a welding shop due to the thickness of the metal and wanting good penetration. Other than that everything was done with the Miller Mig.
When guys talk about what boats will handle at sea the usual response is that it isn't the boat but the captain. Here it isn't the welder but the operator. You need to know how to put down a safe weld under different circumstances and know the limitations of the welder and yours. If in doubt tack it together and have someone else weld it. That usually doesn't cost that much as you have done all the time consuming work.
So with that in mind and if you have no welding experience welding up a cart for the welder would be a good first project. When I bought my TIG I could of welded up the cart very quickly with the MIG but made myself do it with the TIG to gain some experience.
I wouldn't count on using the 190 for much of the aluminum work you would probably need to do like building tanks and such. You just don't have the same control over the weld with a spool gun as you would with the TIG especially if you hadn't welded much. You can get a spool gun for my 180 but a good Miller distributor told me that I wouldn't be using it for much as the 180 didn't have the power to weld thicker aluminum with it and it would probably blow thru thin stuff. I have about $2200 in my 225 amp TIG buy the time I bought it and tanks and supplies and such and now even more but it has been a great investment but for what you want to do I'd start with the MIG and learn how to use it right (college workshop night class maybe??),
Sumner
