Well, given that most conventional masts are supported by stays that exert a large downward force in an effort to extract the small sideways support vector available from the angle of the stay to the mast, I would say that a telescoping mast would be a nightmare to engineer
. The compression
force on the mast would be pretty great just sitting at anchor
, and once the sail is drawing nicely, the increase in compression
force as the stays on the upwind side are loaded up would be huge.
Stayless masts would not have this problem, but then the weight of the mast would problematic (because of the neccesary double-up of the layers of mast to support the joins) and again, sail luff tension would excert significant compression forces in some situations.
Lowering a mast to get under bridges is not that hard if you design for it beforehand, I actually watched a Beneteau
do it recently, and they didn't even stop the boat. They had a crew of about six on board a 40ish footer, and they were re-rigged and hoisting sails within a mile of the bridge. Clearly they had some kind of specialised setup, but the point was the rig looked pretty normal to me.
As for storms, well, reefing a sail seems a lot easier than reefing a mast. Even if you lower the mast, you still have to gather up the excess sail somehow and keep it under control.
No doubt someone has done it, but I bet they found it was not worth the effort. So I guess my take is, sure it should be possible, but the engineering challenges, the weight, the consequences of failure, all outweigh the possible benefits.