Yah, its a stinking mess huh?
I've tried a few methods, the orange stuff - the orange odor alone gets to me after a while and the stuff is probably not much more green or healthier than the methylene chloride, a heat gun, and the methylene chloride based gel. I use the gel now except for smaller parts like thwarts and seats, outwales, and keel, which I use a heat gun on. I do it outside usually with a respirator on for comfort.
Typically it takes about 3 passes with the gel to get it all off. I find if you can do smaller sections with 3 consecutive passes that seems to work well, the varnish stays soft and more comes off with each pass. I use a putty knife to gently scrape. I think if you search on "stripping" you may find other techniques. Time varies with the amount of varnish. I did one last year with a heavy, heavy coating of old black varnish and paint on the decks and rails and it took about 24 hours of stripping to clean it up. Ugh.