One thing to point out here, is for TIG welding aluminum, AC welding capabilities are an absolute must. Only under certain high amperage conditions, using real thick metal, will aluminum cooperate with DC weld current.
TIG is excellent for the thinner stuff. These days, the world is changing over to inverter technology. The machine is lighter, more power efficient, and most importantly for aluminum, much more adjustable. AC frequency is adjustable, alternating between wave types is adjustable etc. I personally feel that if you want to weld aluminum, and be real serious about it, the extra adjustment capabilities of the inverter machine is essential. I am personally looking into getting a Thermal Arc 185 the very day my boat sells. The 300 amp machine is awesome, but it is very costly.
For thicker stuff, say 1/8 inch and larger, especially doing the quantity of welds on a boat, a MIG is likely the better choice. However, spoolgun, or push/pull is essential. While aluminum
can be welded with a smaller machine, I personally wouldn't go under a 210 class machine (that is the point at which Miller and Lincoln switch from consumer grade to a much better industrial grade machine). I am personally getting a Millermatic 252 with Spoolmatic 30A spoolgun fairly soon after the TIG.
You can stick weld aluminum, but it isn't exactly ideal. If you are proficient at Oxy-A welding, TIG shouldn't be hard to pick up. The concept and hand movement is very similar.
I envisioned a Single guy or with a willing escort, a big Truck, with the Welding stuff in the Back, a Boat on behind that, just traveling with the warm weather looking for adventure and the Welder paying the way.
That is somewhat where I want to be in a few years. I don't want to be limited to the boats, however. I'm seeing myself in one to two man fab shop, MIG, TIG, stick, plasma etc capable, with benders, bandsaws, etc, to cover the whole fabrication end, not merely welding jobs. Also, I see myself with a truck with engine driven setup (think Lincoln Ranger 250 GXT, or Miller Trailblazer, both of which are stick capable, and can have a "backpack" wire feed setup attachment. Also, the 11,000 watt AC power output would allow TIG and plasma capabilities on the truck. Be set up with portabands, compressor etc, to be fully fab and repair capable on the road. Sure, to achieve this at the age I want to achieve this by, I am likely going to have to scrap the idea of the 20 ft. plate boat, at least until a later date, but it is likely the wiser choice for me.
I currently do a number of small steel fab jobs on the side, and once I get the Thermal Arc, and have a few more capabilities because of it, I plan on setting up a little website, and doing a little advertising. At this point, all of my jobs have walked right up to me, without me advertising in any way, other than people seeing my own work in various places.