What I was told when attempting my repairs was a warm temp (20 deg ish) and low humidity were essential. I didn't have either, which was probably part of the problem. Unless you live in the Sahara, outside repairs could be a problem. Having said that I have done a couple of smaller patches in other places with no problem, always tried to do it with sun on the tubes to keep it warm.
A Boat is a hole in the water, surrounded by fibreglass, into which you throw money...
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