On Vee Jay our most serious concern is headstay sag.
The heavy foil for the Harken RF foil in a 3+ ft wave can wipsaw back and forth ... and while the foil segment connections on the current foil appear to be way better than the old foil using pins ... I am shy as to just how much wipsaw effect i want to have ... you have to see floppy foil action to believe it.

to gain reasonable tension I have shortened the forestay length ~3.5 inches ... which of course makes the OD jenny length too long. We still get some wipsaw action ...

but this move on the Vee Jays part is to one get two boats as close in specs as possible and to try to get to maximum OD headstay length ...

other than that ... other people need to come into this conversation to talk the theory with the idea of course that a carbon foil probably weighs a tenth of the aluminium RF foil.