Balance wise, from memory I felt she was well balanced, although it has hydraulic wheel steering and a big rudder so that limited the feel of any discrepancy. 

And yes, so much information. I can't help feel I'll just end up with the scaled up SJR for Ms Murphy and just go with what has been shown to work. But it fun thinking and scheming other possible modifications.

Thomas, I guess you are now near being saturated with ‘information’ from all corners of the world.
I wonder; did you ever get in some sailing with the original rig? I have found it useful to sail my boats as they are, for at least one season, just to get to know the boats’ character. This makes it easier to choose a JR with the right size and CE position.
Just a thought.

Arne

Thanks for that Paul, looks like it should work well for a sloop conversion which is great . 

Am I right in thinking the high peaked yard is less ideal for the SJR as the force required to get the high peak slings the rig forward, adding stresses or requiring some means of holding the rig where you want it, parrels?

If there was a rigid parrel in one form or another on the top horizontal batten, it could allow the high peak (more sail per mast length) but allow the rest of the rig to hang happily from a fixed batten length. 

I feel a hybrid (word of the year?) between Arne high peak, Slieve SJR and elements of Paul's Aerorig would be interesting. High peaked top with camber, flat cut main with wishbone battens and SJR jibblets. I wonder it it would work? Thoughts? I think Paul Mckay had a similar idea but with origami jibblets.

Thomas, very fascinating project you have on your list. I wish you good luck!

I follow this threat with great enthusiasm, but unfortunately lack the capacity these days to participate.

Just one thing about Arne's last post about mast balance: it is true, I built Ilvy with 27-28% mast balance, and it works well. 

However, I put up the theory that even the "standard" cambered rig, like Arne draws them, can be built with ~33% mast balance (not more). I myself have no practical prove for that claim, but:

1. Aerodynamics tell that at about 33-35% is the position of the neutral point of an airfoil, and as such the maximum of mast balance. 

2. If I remember correctly, Paul Thompson did already built sails with a mast balance higher than 30%. Correct me if I'm wrong.

Slieve did a fine job using the almost maximum possible mast balance, close to the neutral point. I see no reason, from a fluiddynamic perspective, why the non-split rig shouldn't be capable of the same. (That discussion is maybe something for its own thread...)

I hope to soon be able to participate more in this forum and topic again. The CFD calculations are still on my list, but life came in between...

Cheers

Paul

Graeme wrote:

Arne – interesting that you give credit to Martin and his Custard for solving the “halyard angle issue”. While not wishing to take anything away from Martin, a couple of things crossed my mind immediately. Firstly, I might be wrong, but it looks as though the mast balance of Custard is a bit less than 33% (I might be wrong, we need to check) and also, in the Magazine No. 83 article it states that Martin used ultra short, very slippery mast parrels. Both of these things may be contributing to the solution of that issue.

At some stage I would like to see a discussion about rigid mast parrels, because that's where the answer may properly lie. I think Steve D (Serenity) and Jan Cz with his little boat may have cracked it. (Wingsails and double wishbone aerojunk sails ditto).

Rigid parrels: You’ll have seen in another topic that I’ve been working with Jeff M. to make a mast with 3D printed components, for his Konsort 29 Chisco. He had an SJR on Sesi (which was the same size as Poppy, IIRC), the boat that he lost off Anglesey (written about in JRA Magazine issue 97), and is making an Amiina-style sail again. But I can’t persuade him to come onto the forum and discuss the design with his peers, to check that he will be making a state of the art rig. If Poppy was “Genesis” and Amiina is “Old Testament”, we are, or we should be, now looking at the “New Testament - The gospel according to …”.

However, he did have a rigid hoop made from a large piece of PVC pipe, attaching his boom to the mast, is very firmly convinced of its benefit, and has been asking me to come up with a better version of it. I’ve tried to mould one, using some Kevlar braid left over from Weaverbird’s wing sail, but not very successfully. In essence, the principle is the same as those mentioned above. It was to be attached with Jubilee hose clips. I’m not sure that it could be used on battens above the point where the mast diameter begins to decrease; that would need to be tried. Anyway, I’ve passed the mould and spare Kevlar on to him, to see what he can do with it.