flaming
Well-known member
The issues that the IMOCAs have been having is that stability derived from foils is dynamic. So whilst the RM of the keel at max cant, and the form stability can be pretty accurately calculated and will not increase, the faster the boat goes the more RM is generated. And then, in theory the more sail can be set, and the faster the boat goes...
Several years ago, pre foiling, the class went to an OD mast to try and reduce the amount of dismastings and save costs. It is now acknowledged that the limits of the OD mast are now preventing the boats from going faster. And that a lot of money is being spend on very sophisticated force monitors to detect when the loads are getting too much for the mast.
I've also read things from the figaro fleet that sailing with a foil is quite a different experience. As a decent proportion of your RM is derived from your speed, you can have some interesting moments if you suddenly slow, say by plowing into a wave. And the pilots are having real trouble helming them efficiently in breeze. This seems to be because in effect you can hold more sail for the point of sail once you are moving than you could if you just sheeted in from a dead stop. So if you're on a reach and your speed dips you must bear away to an angle that you can hold that amount of sail without the foil RM and hunt speed before trying to get back on course.
