N30 Full Hoist

Questions & Answers
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1

The P dimension for a N30 is 45ft. On my mast that’s also the distance from the tack to the upper black band. My sail has a luff lenghth of 43’ 6” and, when hoisted, its obvious that there is room for it to go higher. Pics that I’ve found of N30’s sailing with the full sail visible also show a hoist short of the black band as common. I’m condsidering a new sail and the initial proposal is for a luff of 43’ 11”. My question is, is there a reason not to have sail that can be hosited to the black band? E.g. with the max allowable roach, would the leech get stuck on the topping lift when tacking?

Thanks

Martin N30 #33 ZENO Toronto

2

I’m hoping someone who knows this topic can chip in, because I’ve got things I’m wondering about, too.

I’ve noticed that no matter how hard I crank the halyard on my brand-new sail with my brand-new low-stretch halyard and my brand-new electric winch handle, I can still see scallops develop after a while. My sailmaker has told me that if I really want those to go away, I need to install a cunningham.

My sailmaker is better at making pronouncements than explaining them. He’s especially prone to pronouncements that mean more money for himself. So, he hasn’t told me why, and I wouldn’t trust his answer if he had. I’m left to guess on my own.

My current guess is that it’s because the curvature of the mast means that getting the rest of the way to tightness after the mast starts bending is not just trying to pull the halyard uphill but also along a backwards curve.

This would make the top sail slides want to dig into the track rather than slide up them. Since a cunningham would be pulling down and the mast isn’t bending where it’d be located, it wouldn’t have the same fight. Don’t know if I’m making sense, this is just my guess.

Martin’s question about the difference between sail luff and distance between black bands made me wonder. Could the issue of flattening the sail in the face of mast-bend be related to both questions?

If the sail extended the full length of the distance between the bands when our slightly curved masts are in resting position, wouldn’t that lead to bagginess when the mast bends under pressure of wind and rigging settings? If so, you’d need the luff to be less so there’s room to still operate effectively under heavy conditions.

So maybe mast bend affects both the benefits of cunninghams and Martin’s question.

Again, don’t know enough to do more than questions.

Anyone out there who knows about this stuff and can provide definitive answers?

Thanks,

– Bob

P.S. And, I’m not advocating cunninghams. I decided for the sailing I do, I’d rather have scallops than spaghetti.

3

I don’t have an answer to Bobs question, but have a question about luff curves, which may be related to Bob’s question. This pic shows my current sail with the luff tightened using a rachet strap and a tape measure running from the tack to the head. Note there is additional material fwd of the straight line taken by the tape measure. This material looks like it allows the sail to follow the curve of the mast. I understand the distance bewteen the actual luff and the theorectical luff of the tape measure is referred to as forming the “luff curve”. The max depth of the curve on the current sail is 9.5”. The specs for the new sail are for a max value 6”. It seems to me that if the luff curve built into the sail matches the bend in the mast due to the weight of the wishbone and sail, but no wind load, then it should be possible (and maybe easy) to hoist the sail so the luff is tight. However if the luff curve of the sail is greater than the mast curve, then it wont be possible tighten the luff and remove all scallops/wrinkles. Similarly if the curve on the sail is less than the curve on the mast, then as the sail is hoisted it will be trying (unsuccessfully) to straighten the mast and will show stress points along the luff.

Does anyone have info on the importance of getting the luff curve right and how much the curves can be mismatched before it makes a noticeable difference to the appearance of the sail.

WRT to Bob’s sailmaker’s recommendation for a cunningham. Perhaps the question for the sailmaker is how do many other boats without a cunningham avoid a scalloped luff.

Current sail pic
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Martin N30C ZENO Toronto

4

My new sail (fareastsails.com) is 45’6” on the luff and comes to about 6” below the black line when tight. I had a Cunningham cringle installed but have never seen the need. Under full press, (see picture) I don’t get any scallops in the luff if I have raised it tight with my Milwaukee drill.

Maybe your tack fitting is lower than mine.

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5

I am not that expert! But neither are most sailmakers or riggers around here. I (like Bob) am in an area where Nonsuches are very little known among the professional community. But you can’t swing a dead cat without hitting an expert on sloops. While there are similarities, I am almost always disappointed when I deal with the pros around here. From the smallest things to the largest. And that’s only the things that I know about. I’m still on my learning curve, too. Just farther up it than the sloop experts. Do we need Cunninghams? I don’t know. But if it was me I’d only take it from the actual Nonsuch experts, some of which seem not to have made the transition to Discourse.

Edit… See: there’s Paul who has a Cunningham and doesn’t need it. I’d trust him a lot more than a sloop specialist. And my manual says nothing about Cunninghams, either.

6

About the leach / topping lift issue….

My sail is 612 sq’. The Nonsuch literature says 30s are 540 sq’. I think that is the straight line triangle and the extra is my leach. It overlaps my topping lift a lot but as the TL is always slack it is a non issue.

7

I’m expert enough to confirm that the “official” Nonsuch sail area measurements are right triangles that don’t capture all of the sail area.

The official P measurement is the vertical distance from head to tack, as shown in Martin’s photo. The official E measurement is the horizontal distance from the clew to the mast.

The stated sail areas of our boats treat those two measurements as a right triangle, and use the standard formula for a right triangle of (P * E) / 2.

All the sails have additional area: their roach, plus the little section Martin’s picture showed, plus whatever’s below the horizontal line from clew to mast.

– Bob

8

Thanks for that Bob. It was hard to believe it was all roach even though my new sail has a lot more than my old one had.

9

It’s impressive how the actuals differ.

The difference between official sail area and actual on yours is 13.3% according to my calculator.

On my N26, the official sail area is 420 sq. ft., while my new sail comes in at 481 sq. ft., which works out to 14.5% larger.

– Bob

P.S. I’m not a cunningham advocate either, as it turns out. I’m not totally happy with how my sail was cut. I wish the clew had been designed a bit higher, for example. I don’t have the kind of space that would permit laying out the sail like Martin did, but I wouldn’t be surprised if the luff curvature didn’t perfectly match the boom curvature.

10

I’m not an expert, but I think what’s happening here is mostly a geometry thing rather than a sign that the luff was actually cut with a curve.

When you lay a mainsail flat on the floor, you’re forcing a three-dimensional shape to lie in two dimensions. Because the sail has draft built in from the broadseams, there’s a bit of extra cloth in the middle. When that shape can’t bulge upward — because it’s pressed flat against the floor — the edges, especially the luff, tend to shift slightly forward. That makes the luff look curved even though it probably isn’t.

When the sail is hoisted and properly tensioned, the luff will straighten up again. I play with that tension all the time with the halyard to flatten the sail. Increasing halyard tension stretches the luff and pulls some of the draft out of the sail; that’s exactly why there’s a little extra “headroom” in the luff area. At least that’s how I understand it.

On bigger boats, the cunningham is a neat solution to the same problem. Instead of cranking on massive halyard tension, you pull the draft downwards from the lower part of the luff. I believe the position of the cunningham is usually about the same distance above the tack as the “free space” above the black band near the top — the same concept, just applied lower down.

As a conclusion, I’d say the sail’s own draft probably has far more influence on the apparent “curvature” of the luff when the sail is lying flat. If there were any built-in shape meant to match mast bend, that would actually have serious consequences for the draft: a convex luff would add depth to the sail just when the mast bends aft — exactly the opposite of what you want. Our un-stayed masts bending, are meant to flatten the sail, not make it fuller. The hollow aft side of the mast effectively “absorbs” some sailcloth and pulls the draft out — which is precisely what you want as the loads go up.

11

I would not ask a sailmaker to make changes ( to what they propose ) unless I was absolutely sure I understood the impact.

If you doubt your current sail is optimal, identify a boat that has a sail that performs the way you hope your new sail will perform and use it’s measurements as a basis for your new sail.

Personally, I’m finding the unstayed mast negates much of what I learned from other boats that have stays. The image that keeps coming to mind is “wet noodle”. Just the weight of Soave’s wishbone creates deflection resulting in 8” concave measured at the mast track. This is easy to see by tensioning the flag halyard to lie straight down the mast, then ease the topping lift so your wishbone sit on your bimini or other support. The difference is surprising.

A cunningham is a useful tool for controlling the bottom third of the sail if the halyard tension isn’t sufficient. I’d lube my slugs first and possibly ease the choker between adjustments to see if I really need the cunningham.

I know boats that have customized sails, they are usually top flight racers that partner with a sailmaker looking to become a preferred sailmaker for a one-design racing fleet. It takes multiple iterations to beat the “off-the-rack” versions of the sail…. then the new pattern becomes the off-the-rack” sail.

Good luck with whatever you decide and please publish results to help the next sailor.

12

Sounds like sloop sails to me. They are stuck onto straight (or almost straight) masts. Our masts curve aft - quite a lot. I don’t get how a sail with a straight luff would ever hang right.

13

The excerpt supports the view that our sails have or should have a curve built into the luff.

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{47EA50E3-39C0-42E0-A73F-B7FE390D0D20}857×738 156 KB

15

I initially posed this question as means to increase my confidence that the sailmaker’s proposed specs for my new sail would produce a good result. Through the reach of the INA membership and input from several members I was able to access CAD level data for sails they built and to compare that to the same CAD level specs the sailmaker gave me. This is a fantastic outcome and one that I’m extremely appreciative of. There is nothing that compares to the collective experience of INA members.

While I got what I needed, unfortunately I don’t think my question(s) have added to a concensus on how Nonsuch sails should be designed. Perhaps what might be helpful is to skip the theory and to have available on the INA website a table showing the detailed design specs for sails that members have built, the conditions they were designed for and their “happiness” with the sail.

16

2 posts were merged into an existing topic: Planning for new sail

18

I don’t want to derail this thread, so I created a new one to discuss my potential new sail. It is here. Is it possible to move the previous two posts to that thread?

19

Brian,

Yes, it is possible to move posts into a more appropriate thread, and makes a lot of sense.

I just did it.

I think clicking on the “here” in your message or my quote of it above, will take folks to that new thread.

(Gosh I love Discourse!)

You’ll find them in front of your post for the new thread, because I selected them to move over in chronological order.

– Bob