Just for the record,

In a posting below here, Spence Mooney indicated that he was about to make a cambered panel junk sail for his Corribee MkII.

Last June he sent me a report with the photos shown below. He cut the panels with round plus broadseams and then assembled the sail along the battens, using the sailmaker’s method. This gave him quite a struggle, which ended with some wrinkles along the luff. Nevertheless, the finished sail (around 19m²) looks good on the boat, in my eyes.

Cheers, Arne

    

 

I find that Siskin has strong luffing tendencies on the port tack and is more or less stable on the rudder on the starboard tack. She requires 35 – 40 degrees of rudder input on the port tack and 5 – 10 degrees on the starboard tack. Similar results hard on the wind, on a beam reach or running. Conditions where about force 5 – 6.

I now believe that the engine being in the water starboard aft has something do with it. So I think that the breaking effect of the engine in the water more or less functions as force to reduce the luffing on the starboard tack. On the port tack the engine gets more less lifted out of the water (something I can hear when I tried motorsailing her on the port tack) The mast on a Coromandel is too far aft to start with but I don't see how this could easily be fixed.

What are my options here:
(1) Life with it – these are not major issues compared to other problems;
(2) Get engine out of the water while under way – make the engine hood fit with the starboard aft hatch closed is the challenge here even though I switched to the far smaller Yamaha Malta engine;
(3) Increase rudder size – making for a more powerful rudder input at smaller rudder angles;
(4) Move the mast forward – major reconstruction required;
(5) Increase mast rake forward – major reconstruction required – i would think(?);
(6) Get sail with a significantly larger portion of cloth further forward – maybe jiblets?

I now think that a combination of options 2 and 6 would be the best way to go. I’d be interested to learn how one would rake a mast forward on a Coromandel. That would be a useful addition too.

Siskin will probably get windvane steering – I think this wil only work properly when this imbalance between port and starboard tack gets resolved and the balance in the rig is restored one way or the other.

Please correct my thinking where required.

Richard, I've been looking very hard at Paul McKay's Aerojunk rig as a replacement on my Coromandel. The more I learn, the more impressed I am. Paul is presently reaching hull speed on his Etap 23 (about 5.9 knots measured by GPS) in Force 3 on a close reach, and can sail efficiently closer to the wind than conventional JR, despite having 35 square feet less sail area than the original main + genoa. What is particularly attractive about this rig is that the sail is made flat, camber is induced by the curvature of the wishbone 'cage' and that home construction of the whole thing looks relatively straightforward for anyone with basic skills, with no expensive components requiring specialist manufacture. The 'slot effect' produced by the separation of 'jib' and 'main' components is clearly contributing greatly to the efficiency of this rig, while the simplicity of the self-tacking design augurs well for longevity and easy handling. Perhaps you should add Paul's rig to your list of possible options? Paul has been extremely helpful and communicative and has already drafted a design for my Coromandel which will allow a significant amount of adjust-ability to move the CoE and compensate for any issues with mast positioning and lee/weather helm, since I'm still in doubt as to the actual characteristics of the Coromandel in this regard. Inpassing, thank you for the link to the Hebridean self steering kit; looks really well-thought-out and finally within reach of those of us on limited budgets.

Hello Chris.

The answers to most of your questions are here http://tammynorie.wordpress.com/2014/10/01/autumn-plans/

Do let me know if you have any further questions, though. I expect I'll be writing a lost more about my preparations on the blog.

Richard Brooksby wrote:

A few questions:

• Do I have my facts straight?
• Does anyone have links or references for information about the various batten schemes?
• What mistakes am I making?
• What factors have I forgotten?
• Any opinions on open issues: sailcloth, batten material, sheeting scheme, or anything else?
  
• What would you do?

Yes, you have your facts straight. I'd add the regular sailmaker's way of cambering panels - a separate shelf at top and bottom of each panel; and broad-seaming of vertical cloths.

For performance and control, I'd use an upper and a lower sheet, as Edward now has on Amiina, and as I had on my large Fantail sail -two vastly different sail shapes, but both better controlled.

Sailcloth - see if you can get some Sunwing cloth from Kayospruce. It is no longer in production, but is the best cruising cloth for JR, IMHO, unless you want to leave the sail uncovered, in which case you could go for Odyssey III.

Battens - aluminium alloy tube would be the easiest option, with pultruded GRP also a contender.

What would I do? A smaller version of Fantail's sail. But then, I'm biassed.