Slieve McGalliard wrote:I have seen a number of very experienced junk rig sailors sail my rig and not get good performance. They always seem to stall it by oversheeting, and some could not be persuaded to ease sheets.
I have come to the conclusion that flat sails and sails with flat entry to the camber seem to need to be oversheeted to produce any drive from the high pressure on the windward side, ignoring the loss of the low pressure on the leeward side. Some may be happy to sail like that, and it matters little with a flat sail as knife edge separation kills the low pressure, but it is death to a well cambered sail and robs it of its high lift/ drag potential.
Hi Slieve,
Thanks for your response... I've moved over to the other forum thread (PBO something'r'other), where I've asked about the role of twist control of camber draught (Reddish theory), both in general and for SJR in particular.
I can visualize what you're saying, here, and it makes intuitive sense to me. It seems that the attack angle of the jiblets is the key, and any over-sheeting anywhere along the sail would detract from optimal. This would rule out twist as a lift enhancing control.
Of course, one could always de-power the SJR by over-sheeting, as a maneuver. But I see that as a whole sail maneuver, in general, rather than merely inducing twist.
I'm guessing that Reddish twist theory (as I understand it) applies strongly to flat-cut and fanned sails, not sure about standard, cambered sails, but probably not at all to SJR.
I look forward to your comments on the other thread!
Dave Z