I used a 110 Millermatic mig machine to patch several cracks in my boat. Worked perfectly. Best advice I was given was to make sure the feed tube is as straight as possible. I put boxes under the tube so there were no dips or loops. I had no feeding problems at all even with an old liner. Main issues I ran into were heat control, I had to bump up the heat and make small passes to prevent the weld from puddeling up. I also had to hold the arc further away from the aluminum.
The boat held up perfect all year even with some big waves.
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