I remember standing on the deck of Johanna with Nils Myklebust viewing along a panel from luff to leech while I tried to measure the depth of camber from his direct view and the sail material. This way we were measuring the max depth of camber from luff to leech. If you measure from batten to batten as it Arne's photo you have to make allowances for the thickness of the batten  and possibly measure both sides of the sail if the battens are fastened to one side of the sail, which is often the case.

Maximum camber is not necessarily going to give the best information. A lot depends on the shape of the camber from batten to batten, whether it is a 'V' shape or a broad flat 'U' shape. The cross sectional area of the camber might be as important or even more so. 

Think of a tinplate horizontal shelf foot panel where the camber would be at maximum depth over the full height of the panel, and compare that to a simple soft material with an arc of a circle cross section. There would be quite a difference in the area of the camber shape and therefore it would seem a difference in resultant performance.

This suggests that the different methods of camber construction could have perhaps as much effect on the performance as the maximum depth of camber. The flat shelf foot would probably have the biggest cross sectional area for a given maximum camber depth, the 45° angled shelf foot might come next, but that might depend on how the broadseam was designed and how many seams were used in a 'round and broadseam' panel. The simpler to construct round only panels might have the lowest cross sectional area for the same maximum camber, but with a simple increase in maximum camber could have equal camber area.

What I'm suggesting is that simple camber numbers might give misleading impressions, and that maximum camber and camber construction would probably be needed to form a realistic comparison. I dreamt up the angled shelf foot as a means of getting as flat a cross section camber right from the luff of the jib panels, and of course the leech ends become  more like the arc of a circle, and this is why I am still struggling to find the ideal shape for the jib panel camber. What we are now using is not my ideal, but it seems to work well and until someone finds better it is well worth using.

Cheers, Slieve.

Hey Thanks Arne, 

and thanks for the album tip- yes my IT skills are non existent,I’ll try and sort them in due course.

The camber is calculated camber, and arrived at by magic- using Slieve’s fabulous Round and Broadseam calculator.

I just entered the parameters supplied by Slieve and it spewed out all the relevant measurements..

Slieve felt that a slightly flatter main panel at 7% was worth trying (I think many of the previous incarnations used 8%), as he believes most of the drive comes from the Jiblets. Knowing nothing of these matters I simply followed all of his suggestions to the letter- it was a good feeling, Slieve was actually building my sail via remote control, all I had to do was put the hours in!

If it would be of interest to you or others, I’d be happy to measure the actual camber next time I’m out.

BTW - my Arne Yard looks great on top of my rig.

So thinking about it my conversion is quite a melange..

I’ve got a -

David Tyler Masthead Unit (and I think the sheeting arrangement sent me by Edward Hooper may be David’s as well)

Arne Kverneland Yard and Mast Step

Slieve McGalliard Split Junk sail

.....talk about standing on the shoulders of giants.

Cheers

Paul

Ps there’s even a bit of me in it too- I did the Mast Partners..

Thanks guys,

congrats to you too Jami on your beautiful yellow sail..

Ed, I’ve gone initially with the sheeting as per the diagram you sent me, will also try your split sheet system in due course.

Bloody marvelous Paul.

I agree the picture of your feet and the mast and sail says it all.

Thanks Guys,

courage? That’s why I bought cheap cloth haha

knowhow? Me neither, but I know a man that does..