eerik mee wrote:  Can it be caused by fact that the widest point of camber on a panel is a bit shifted (due to 10% boom angle) across panel? That would make sense as on top panels the difference is insignificant on Johanna type sail.

Regards,

Eerik

I don't know, Eerik, but my hunch is that on the almost triangular two top panels the luffs are so short that the battens hardly can move backwards or forwards. No movement, no creases. Therefore I have never needed Hong Kong parrels on these two panels.

Funny that, Eerik,
my experience is that the two top panels are the easiest to make set well, both with sail fully up and when deeply reefed. The (very modest) camber in the top panels ensures that the leech will never flutter. The only downside with having cambered top panels is that the sail will be suspended at the yard from luff and leech, so the yard must be a bit stronger in the vertical plane (similar to an ordinary lugsail?). No big deal, really on such a small boat.

Arne

(click on photos to enlarge)

eerik mee wrote:

hi Arne,

Thank you very much for your input! You are right, of course with your concern... What do you think about this a bit towards Reddish design?

Here I have drawn 2 different halyard lines: at mid point and at angle 20 degrees, I believe you have said up to 30 could be used, so it should be somewhere in this range...

I didn't plan to have camber on 2 top panels, in this design the third panel would be transitional.

 

Regards,

Eerik

Hi Eerik,

yes, I think this will work better. You only need to make a longish extension on the yard to keep it from falling forward of the topping lift as you reef.

Just for fun I made a sketch myself, using chapter 3 and then I drew up a sail, based on the AR=2.0 master sail (chapter 4), but with one panel removed so the aspect ratio dropped to 1.77.

The sail area with battens at 3.24m came out at 14.05sqm. Still, I am sure your new sailplan is just as good.

Good luck,
Arne

PS: So you think that the traditional top panels are flat? That depends how traditional ;-) ...

Arne Kverneland wrote:

Erik,
I admit to be a bit sceptic to one specific detail of your rig; the position of the halyard’s slingpoint on the yard , and also the aft-pointing halyard with full sail up. This setup may be fine and even necessary if you use a western un-battened lugrig, but on a junk it could easily lead to a tail-heavy sail which will miss-behave during hoisting and lowering..

I suggest you redraw the sail with shorter luff and a taller raking yard, to bring the slingpoint (at the middle of, or a bit aft of the middle of the yard) closer to the mast. That will improve handling (hoisting, reefing, furling) the sail.

Cheers, Arne

PS: If you cut a bit camber even into the top panels, there will be no need for cutting hollow in the leech of these panels.

hi Arne,

Thank you very much for your input! You are right, of course with your concern... What do you think about this a bit towards Reddish design?

Here I have drawn 2 different halyard lines: at mid point and at angle 20 degrees, I believe you have said up to 30 could be used, so it should be somewhere in this range...

I didn't plan to have camber on 2 top panels, in this design the third panel would be transitional.

Regards,

Eerik

Looks good Eeric.    Are you going to have a jointed mast with a hinge immediately above the sail bundle, so that you can get under low bridges easily and make the boat ready for trailing? Being quick to rig and de-rig is one of the central advantages of the Paradox .

As the Paradox has only a 4 foot beam, it's a bit tender and it would pay to keep the weight of sail/battens and rigging to the minimum that you can.

Best

Jim