Welding Tips and Tricks

hello
i am welding .125 alum.with 4043 .035 wire . I am adding a 4 foot section into 46 foot pontunes approx 3' high and 30" wide. I have them tacked together and in place but now i am out side at the boat. My question is what temp out side should it be before i weld the pontunes seams. Our outside temp is 10 -15 deg cell or 50 -60 above, should i pre heat before welding or waite till the temp gets higher. I am concerned about the weld cracking.

thank you in advance for youre help

kim

does it have baffles inside ?
the temp outside won't affect you as much as wind.
skip weld the seams.four to six inches between starts and stops.
weld a few bungs ....1/2" female pipe...so you can flood/purge the 'toon before you weld.
now you know what i know.