What are the pros and cons of an aluminum hull sailing yacht?

They work exactly as the design of the boat dictates. You would not interpret a design for another material, such as wood, GRP etc. and try to use Alloy instead, you will use a plan designed for the use of Alloy only. It will do very well, and has been used extensively in all oceans. You must be very serious about controlling stray currents and any dissimilar metal contact - electrolysis can destroy a new hull within 24 hrs if current is allowed to flow through any part of it. Painting alloy looks nice, but actually promotes hidden corrosion in the long term without frequent close and careful inspection and repair - impossible in practice internally once fitted out. Overall it is an expensive, but very good boatbuilding method. Repairs in remote places can be problematic, but modern two part compounds, or even flat sheet, stickyflex and a heap of rivets can get you out of trouble and back to a MIG. All hull materials have pros and cons, mostly they even out. Go with what you are comfortable with and choose a proven design.

For around-the-world or other exotic cruising - you can get steel welded anywhere within reason. Carry some steel and rods with you and you're in even better shape. Welding aluminum out in the back of beyond is a lot less likely. It requires MIG or TIG both of which need shielding gas and (comparatively) expensive gear and have other finickyish consumables. For me that would be a strong point against aluminum.

well, first you have to be fanatical about keeping stray current away from your boat......a ring beam bond for grounding, as an example where everything is in a closed loop and NOT to the sea........and be super paranoid about who you tie up next to........I've seen stray current at docks eat sacrificial zincs the size of the New York phone book in two weeks... likewise painting with anti fouling is way more complex as you have to properly paint many many many barrier coats on before the copper, or use a less efficient a/f........ Noise and heat: like living in a drum? Sailing to windward in a metal boat is like that......so you have to insulate the heck out of them.......and my good friends have a nearly indestructible steel yawl across the dock from me here in St Thomas....from around 10 to 5 o'clock you cant touch the deck and down below is 15 degrees above air temp.....so insulation again comes up then there's the strength weight issue........a 1/4 " of steel between me and the sea or a 3/8th alloy? aluminum is great if weight is an issue......like in an airplane or a Formula One......when sailing offshore, strength is what you want...( 1 and 1/4 " mahogany hull works for me!) If you are desperately in love with an alloy boat, then learn to weld and go for it......other wise and older fiberglass boat or steel or wood ( no ferro, please!)

Shark Weak: The definition of yacht is "A medium-sized sailboat equipped for cruising or racing" which is exactly what he needs. Get your facts right next time before you embarrass yourself. Jeez everyone has to start somewhere give the kid a break.

Aluminum is a great choice for offshore blue water sailing. It's near the top of the list of my hull material choices for my next boat. I've lived aboard a fiberglass sailboat for 10 years and circumnavigated as well as deliver yachts professionally. I'm actually writing a series of articles on the pros and cons of all the available hull materials at: http://lifeasahuman.com/author/decaptain/

Right on Walloon! Shark Weak is a whiny *****

Just an add on to previous answers. Aluminum can be stick and oxy welded but it is tricky. There are some relatively new products on the market that claim that they can be used with a propane torch.

If you want to sail around the whole world, one, should probably already know the answer.