Re: Going up the mast when the boat is in a lift
I don't think I would go up while it's in the slings, but I have gone up the mast while on the hard, and it's much more productive than going up while in the water. Everything is rock solid; much easier to get work done.
If the boat is blocked up the way I would want it to be anyway, I don't think there's any danger of tipping it. Although you're introducing weight aloft, I can't see how you would generate any lateral force of any significance... you're suspended from the mast, the weight will all bear straight down. Even if you were swinging around like a monkey (which I wouldn't), I doubt you would generate a lot more force than a nasty storm, which is something I would hope the blocking could withstand anyway.
The yard didn't have any problem with me doing it, at any rate, nor was I the only one there who had done so.