I've had in mast furling once before on a 43' Gulfstar. It got stuck immediately so I spoke to my sailmaker. He said if I bought a new sail it would be stronger and yet thinner material so it would easily go into the mast. It stuck immediately and got scuffed up trying to get it out. Went back to the sailmaker who suggested a behind the mast furler, identical to my headsail furler. So, another 2.5K into the sail. That worked perfectly for the seven years we owned that boat. Some folks say it doesn't sail as well but I never noticed any difference. I have a friend with a newer 42' Beneteau sloop with in mast furling. It's been a nightmare for him for the ten years he's owned the boat. Here's a little video clip of exactly what happens on these poor people's boat.