Hi all , we are having another go at building a livaboard Harry ,most wont know that we were getting one professionally built last year only to have the builder string us along and then fold up taking a lot of our and others money with him. Anyway weve tried to kick the idea but it just wont go away so we are planning a fulltime build ourselves around june july next year.
Anyway i would really like a wing sail so heres the deal, if the group can come up with something that fits my parameters i will put it on my boat. What i dont want however is long and convoluted discussions on foil shapes types center of effort etc. This is purely about "the system" the actual means by which we shape the soft wing sail ,the mechanical bit.
A few considerations 1 it must be simple
2 cheap to build
3 easily hoisted and lowered
4 single skin(can have doubled leading edge
5 able to reliably form and hold the desired shape
6 as easy or easier than a conventional rig for a cruising couple to use.
What id also like to lose is the complexity /expense of a rotating mast/masts
As a starting point at the moment my ideas are, multiple hinged battens attached to hoops(think tennis racquet or snow shoe) shaped like an aerodynamic leading edge which wraps around the mast . The battens and hoop would have bolt rope tracks incorporated into the top and bottom surfaces which would allow flat rectangular sailcloth panels with bolt ropes sew into the edges to be threaded/hanked on. This would allow spare panels to be kept and replaced when needed. The hoops would rotate around the mast and would be formed so that they projected some way in front of the mast to add a little more balance (think of the pivot point as at the throat of the tennis racquet) The hoops would either flex around the mast and be tied bolted ie the hoop is under tension or they have a small removable section to allow removal of the assembly from the mast.The battens could be nylon webbing(as for ratchet straps) with matching spacer blocks either side bolted through, the shape and gap of these blocks sets the precise camber of the batten.The spacer blocks would have a groove so that when bolted together they either clamp the bolt roped edge of the sail panel or form a track that the bolt rope edge can thread through. Sheetlets in dyneema would run froneither side of the trailing edge of the battens back to small pulleys mounted on either side of the mast hoop and down to the mast base. Pull one set the sail forms one way pull the other set it forms the other way. Havent put so much thought into the top and bottom most battens but they would be heavier and probably solidly hinged so as not to detr act fron sail shape. topmost batten hoop would have a simple bearing to allow rotation supported by two halyards to keep the bearing flat.If required hoopes coul be also connected by ropes front and back inside the leading edge to remove some stress from the panels maybe reduce twist and as a fail safe to stop the lot coming down if a panel rips.
Thoughts suggestions
Cheers Tim