I wouldn't have said 160A would be man enough for a job like that,If there's allot to do, you would be far better off with a machine thats 200A+ and accepts a reel gun
Do you have the welder already? If so which one is it?
Miller MIG calculator suggests you'll want to be in spray transfer at 23-24V and maybe running around 150 amps. The voltage will be important to get into spray transfer, and getting them will depend a lot on the welder. I assume they mean open circuit volts (OCV). Boats are quite big, so duty cycle will come into it's own. A hobby MIG would be frustrating as it would keep cutting out, and it might not run at those volts. You can use quite a thick wire so I don't think you'd need a spool gun.
Not a lot of help. A lot of people who would know for sure will be on their holidays for a few days.