Tammy Norie has her original sail from 1982 in almost pristine condition. It’s been admired by many people, and more than one person has described it as a textbook example of a Haslar-McLeod rig. That’s all very well, but it’s quite out-of-date with modern junk rig thinking.
The main problem is that the sail is flat. There is no curve in the sail cloth. The battens may bend a tiny bit, and a little bit of curvature is developed by a small amount of slope in the battens, but it’s essentially a “barn door wing” and aerodynamically inefficient. It’s fine when used as drag downwind, when Tammy Norie leaps and surfs as well or better than any boat I’ve sailed, but it just doesn’t drive well to windward.
The Coromandel / Corribee underwater hull is very sweet but fairly full
forrd […] Corribees were built full in the bow to stop diving when running.
One consequence of that is that she gets slapped off the wind by waves, making it even harder to make progress to windward in a chop.
For these reasons, I want to completely replace the sail. I don’t want to modify the existing sail at all — it’s in beautiful condition and it’s a piece of history — so I’ll start from scratch. This gives me a lot of freedom in deciding what to do.
Another issue is Tammy’s mast position. Robin Blain (a very experienced rig developer) told me that the Coromandels’ masts are too far back, and that makes them difficult to tack. I’ve not had trouble with tacking except in a chop, but I think shifting the centre of effort of the sail forward might help. However, I really don’t want to move the mast. It’s in an otherwise well-designed position supported by a reinforced arched coach roof.
Comparing the Coromandel with Annie Hill’s Fantail, a much more recent boat, it doesn’t seem that the partners are far back, but there’s about a 4.5° difference in mast rake.
I believe I can adjust Tammy Norie’s rake and even make it adjustable while sailing but I’ll discuss that in another post.
I also think that Tammy could do with a larger sail area. She doesn’t really get going in anything less than a force 4, and I’ve found that a bit frustrating while cruising around the east coast in summer. I’d like to carry a larger sail area. Junk rigs are so easy to handle and reef that this really shouldn’t be a problem. The only question would be whether the sail efficiency is compromised if I’m reefed in typical conditions. The current sail area (according to the brochure) is 18.3m². (For comparison, Roger Taylor as 26m² on his Achilles 24, Mingming II, and Annie Hill has 29.5m² on her Raven 26, seen above.)
Building a junk rig sail is quite straightforward and I intend to do it myself and learn all about it.
What kind of sail? There are several competing sail plans. I think David Tyler’s “fan tail” looks right, and is supposedly a good cruising compromise. On the other hand, Slieve McGalliard’s split rig (a junk rig with a slot) is very intriguing and makes great claims for upwind and light wind performance. Roger Taylor, on the other hand, has stuck with a simple Haslar-McLeod layout for Mingming II, but with a clever system for introducing curves into the panels that I’ll come to.
Various methods of introducing curves into junk rigs have been tried since the 1980s. I’ll give a very brief summary of them.
- flexible battens seem obvious, but the sail curves more in strong winds and less in light winds, and that’s the opposite of what’s needed. Nobody uses these.
- pre-curved battens that flip inside wide pockets were tried, I believe, but there’s too much friction to allow them to flip over easily.
- jointed battens are a clever method using metal tubes with a clever joint that limits the maximum angle. These are still quite popular, but I don’t like the complexity and the need for special parts.
- barrel cuts are simply a way to cut belly into each panel in a similar way to normal sail making. These are probably the most common these days, but people seem to worry a lot about wrinkles.
- Roger Taylor devised a unique “HHH” system that (as far as I know) only exists on Mingming II. Separate panels hang off the battens by tapes so that the result resembles a piano hinge, and the sail has gaps.
I have to say that I’m very keen on Roger’s method. It has a very simple construction and could be tweaked quite easily while cruising. Tinkering with things is one of the reasons I like the junk rig, and I’m pretty sure it would be easy to adjust the hinges at sea to try out various sail trim ideas. And carry or make spare panels.
So, what I fancy at the moment is a large fan tail sail with curved panels hanging off hinges attached to a mast with adjustable rake.
Sailcoth? Dunno. Batten material? Not sure. Sheeting system? Erm…
Probably all wrong. We shall see.