Thierry Msika wrote:Thanks a lot David,
I think that was a fantastic answer for a newbie like me. You took the time to detail with honesty the relative weaknesses of your rig and point to the relative advantages of the split rig. Those points are the ones it would be good to see included in a digest about rig choices. I am sure other newbies are or will be in my situation and are wondering how to decide, what are the criteria, the different choices, etc.
To sum up, a rig with a higher aspect ratio can create taller panels that are easier to camber. On the other hand the taller the rig the higher the centre of effort that needs to be counteracted.
That may be an oversimplification. Any aspect ratio sail may have more, narrower panels, or fewer, wider panels.
What you don't talk about is how the boat balances when the fanned rig is squared out, the centre of effort going far overboard. Can you swing the whole sail inboard to reduce the ardency when running?
Yes, I do, when I want to run fast in a strong breeze. In light breezes I don't bother, but in strong breezes the easing of the helm pressure is marked.
Oh I see "catchers", you mean the jiblets are loose when reefed and need to be restrained?
Yes, but note that this is conjecture on my part, based on being at sea in bad weather with various kinds of junk rig, observing how they behave. I wish someone would take a split rig on a serious offshore passage, then we'd know for sure.
And the fanned sail is best suited for strong winds. Isn't that already a quality shared by all forms of junk rigs?
I wasn't talking only about performance, but about the way that many stiff battens, with narrower panels, distribute the loads better than fewer battens with wider panels; and about the way that the shorter luff lengths of the panels means that there is less loose cloth to flap about when reefed.
I don't know, I also cruise on a 10 tons Wylo II. I consider the ability to move in very light airs to windward essential. I achieve that with light weight main and jib topsails raking up the faster breeze high up. I can think of many situations where I needed to move in a few knots of breeze, especially because I don't drag a propeller.
To me converting to junk hopefully shouldn't equate to converting to motoring.
It won't, if you put a very, very big powerful rig on (as Arne and Ketil do in Norway), or if you put on a slightly more sophisticated, and slightly more efficient, split-rig.
Finally what do you all think of Paul's wishbone split aerojunk rig? This is completely untested in the first stage of design and I haven't seen many comments about it from the experienced junkies. The idea has been around for quite a while. Or does no one dare give a comment?
Yes, I dare. This is a design concept only, that has got to the stage of a non-sailing model, and is now looking for someone to build at least a dinghy size rig. We won't know the value of the concept until someone does. I don't think that the extra work in building it will be matched by commensurate gains in performance, but I'm willing to be proved wrong. My guess is that there will be some practical difficulties to be worked through before a successful rig is achieved. I really don't like the thought of all those exposed external wishbones, with their parasitic drag and the wind noise they will generate. Much better, in my view, to put the wishbones inside the sail, as I did on the wingsail rig that I used up until last Spring. Then you get the added advantage of a sail cross section that is much closer to the rounded leading edge and gradually increasing radius of curvature on the lee side that characterises efficient airfoil sections. The sail is still cut flat, as in Paul's Aerojunk.
Cheers
Thierry