Reef points

[William Evans]

Jim  Cosgrove of Fate started a discussion of reef block

positioning on his boom on his 30.

My reef block positions are not the same as his. That got me to thinking about my sail made by North in 03. Here is a pic of my 2nd reef tied in as a example.

Does it look correct or should the reef cringle be down to the block?

Thanks,  Bill Evans companionship, #465 30U Galesville MD.

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William Evans
“Companionship “ 30U #465
West River MD.

[Ernie Abugov N22 - #56 "Moustaches" Toronto]

William -

My boat is much smaller than yours (an NS22) but I think that the basic philosophy is the same. If we are being fussy, I think that our sails arecut such that the actual cringle will sit as close to the cheek block (port) or tied-off position (starboard) as possible and closer than yours is shown. But, by using a block for the reefing line to go through instead of the cringle, you are only increasing the distance around, say, 8", maybe ?? What's really going on is that the actual cringle, as shown in the photo, is several feet away from the cheek block. This simply suggests that you hauled on the reefing line as best you could, while out sailing, and that's as tight as you could pull it.

IF you had tied in this 2nd reef, on a calm day, at the dock, it would be interesting to see if you could have got the line tighter and the cringle closer.

On my boat, I don't use a floating block on a line tied to the clew - I just go straight through the cringle. And, I have a nasty habit of tying ALL reefs in at the dock if it's really blowing out there. Having the first reef already tied in doesn't get in the way of the second reef tied in. So, with all of that, I've attached a close-up shot of my 2nd reef clew cringle, showing that it is pulled SERIOUSLY tight such that the cringle is really close to the boom cheeck block/boom tie-up position. Look carefully - it's hard too see the actual clew but it's there, half hidden by the boom. If I was out sailing and and had to reef, I don't think I'd have gotten it as tight and neat as this (as I don't put the reefing lines on winches).

Does any of this even vaguely help ???

Ernie A. in Toronto

[Joe Valinoti]

William:  Could you send this photo as an attachment so I can manipulate it??

 

Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA

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[William Evans]

Ernie,

Yes thanks. I also tie in at the dock when expecting wind. I will try it on calm day at the dock. This is my 20th year with this sail built by North using my old sail That came with the boat.

If I can’t get the cringle closer to the blocks I will suspect the crimgles were installed incorrectly.

Bill Evans

Companionship

#465

Galesville MD

.

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[William Evans]

What is a good email address I will resend a yahoo attachment

Bill Evans

 

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[Joe Valinoti]

You should be able to get it from my email I sent to the group.  However, if not, it’s joes...@gmail.com

 

 

Joe

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[Martin ZENO NS 30C #33 Toronto]

I'm so new to my Nonsuch that I've only had the sail up a couple of times, so I may be completely in left field here.  When faced with this problem with a conventional mainsail, the solution was to move the boom to the cringle since the cringle can't move to the boom.

The sequence for this was 1. Ease the mainsheet so the boom can be raised sufficiently, 2. use the toping lift to get the top of the boom level with the cringle, 3. secure the reef line, 4. Ease the topping until it is no longer supporting the boom, 5. Trim the mainsheet.

I cant tell from the pic, where the topping is positioned, but if there is still some travel left, I would suggest raising it before releasing the main halyard to set the luff reef cringle, that way the leech reef cringle will be better positioned relative to the wishbone reef point.

Martin

ZENO NS 30C # 33 Toronto

[Paul Miller]

Ernie, your leach reef looks tighter than I thought was advised. It looks to be almost straight across, while my understanding was that there should be a reasonably sharp vee (boom-clew-cheek block) to reduce the sideways strain on the wishboom.

Paul M

NS30U #211, Sandpiper 

Cowichan Bay, B.C.

[Bill Wickett EX-22 #38 Makin' Time]

Ease the choker as well as the topping loft. This will allow you to get the cringle, or block, closer to the turning block on the boom. 

Bill

[Ernie Abugov N22 - #56 "Moustaches" Toronto]

Paul -

You've brought up an interesting point. Without getting into measurements, etc. and just going with what I think seems correct (hmmmm ....... ), if I were to raise my sail fully at the dock, with no wind and, of course, ease the topping lift, the clew of the sail would support the aft end of the boom "in a certain place" or, hopefully, in the RIGHT place. I will assume that this is the case with my boat - the boom seems to sit in the right place, heightwise, and it doesn't feel as if it is being pulled back (aft) by anything. I have lots of choker adjustment room. 

So .... still sitting there, no wind, I lower the sail and tie in the 1st reef. I tie the clew reef line such that the line is almost straight across. The boom doesn't move more than a few inches, in any direction. it's as if everything just moved "straight down" - there is no strange tension, etc., in any direction. 

I keep going - tie in the 2nd reef. Same deal. Everything moves straight down and I'm able to achieve the same "almost straight across" clew tie-up. 

More important, when I sail reefed, the sail looks and feels perfect - no bags, pulls, creases, etc. Everything seems to line up. In the photo that you saw, it didn't help matters that the topping lift was, in fact, holding up the end of the boom (as I think I forgot to release it). The only time that I (normally) sail with the topping lift holding up the boom is if the waves are big and the boom is dropping into the drink or if I wish to "scandalise the main" (love that expression). On a calm day, no wind, I lift the aft end of the sail to get some curve into it.

I've attached a PDF showing two lines (a red and a black) to (I hope) illustrate the point that as I drop the sail, the cringles line up with the two locations on the boom that they are "supposed to be aligned with "or so I think". I've also attached a PDF with a few photos of the sail while reefed.

Maybe I'm wrong but what I am doing feels correct (and, I think, looks correct).

Ernie A. in Toronto

[Tim in STL, NS26 White O'morn]

Ernie,

Everything sounded perfect and it all looked good until I got to the clew on the second reef, that just does not look right to me.  Is the topping lift holding up the boom at that point?  What does it look like when the topping lift is slacked?

I can never get the second reef on White O'morn to look right, yours looks much better except for the clew.

Tim in STL
White O’morn NS26U #216
Harbor Point Yacht Club
West Alton, MO

[Ernie Abugov N22 - #56 "Moustaches" Toronto]

Tim -

That is a very deceiving shot (2nd. reef.jpg - not 2nd reef upper). One cannot actually see the 2nd reef clew as it's hidden by the boom. The 1st reef is still tied in so there is some sloppy sail between the 2 clews that wouldn't be there if the 1st reef is was not tied in.

Make sense ?

Ernie A. in Toronto

[Ernie Abugov N22 - #56 "Moustaches" Toronto]

And ..... yes, the topping lift was not slacked off. The sail, normally, looks nice and neat with the 2nd reef in.

Here are 2 more shots of the 2nd reef in. Apologies for the quality.

Ernie A. in Toronto

[Paul Miller]

I get what you are saying Ernie but I think you missed what I was saying. 😁

My concern (not really mine but from studying Nonsuchery) was that if you have a straight line from the bitter end of the reef line to the turning block, then forces created when the wind tries to pull the clew forward will be exerted athwartships creating a bending force on the wishboom tubing.

If the clew is allowed to set further forward on the wishboom the force becomes more along the tubing and is less stressful on it.

…… as I understand it.

I think this is mostly a result of your (admirable) practice of setting the reefs in advance with the sail down. Nothing wrong with caution, especially when sailing alone but …. it would be extremely difficult to pull the reef line to that point if you were sailing at the time.

When you reef under sail you can feel the force it takes to pull that clew back and it is considerable. Think of that force trying to pull the tubes of the boom together.

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Paul M
NS30U #211, Sandpiper

Cowichan Bay B.C.

[Ernie Abugov N22 - #56 "Moustaches" Toronto]

Aha .......   OK - Paul. Point well taken and, come spring, I'll give that a shot. 

I'd love to hear about the experience of others with this question.

Thanks, again.

Ernie A. in Toronto (waiting for spring)

[David Godfrey]

I read in the Botts manual as follows:

"Tighten the leech (clew) reef line until the clew is about 1 foot above the wishbone."

That is pretty much where my clews sat on the 2 reef points.

David Godfrey

NS30C #145 Thursday"s Child

RNSYS Nova Scotia

[Ernie Abugov N22 - #56 "Moustaches" Toronto]

Thanks, David. Much appreciated.

Ernie A. in Toronto

[Mark Powers La Reina 26C Vancouver, B.C.]

Bill,

It is a bit hard to tell from the picture but it looks like the block on the cringle is about 2 feet in front of and one foot above the boom reef block. That appears to be about right. It would be nice to see a picture of the sail when reefed and to see how far back you are able to move the boom. 

Ernie, you clearly have not had a problem with your boom and the reef points however at page 3, Note C in "Nonsuch thots By Botts" it states: "You do not want the clew too close to the wishbone as this overloads the wishbone in the horizontal plane, athwartship, and this could bend the wishbone. Somewhere near a foot above the wishbone is optimum."

What is interesting is that in the photos you attached to your response the boom looks like it is as far back as you can move it and yet there looks to be several feet of sail laying agains the boom. If I was reefed and beating I would have tried to get the sail off of the boom to de-power it.   If you were to ease the clew reef line until the cringle was 1 foot above the boom I suspect you would have even a more difficult time flattening the sail so I am not sure you can take Bott's advice with your current sail.

Mark Powers

[Ernie Abugov N22 - #56 "Moustaches" Toronto]

Mark -

You, Paul and others have awakened me to the notion (correct, I may add) that by not keeping the clew a little above and forward of the line between the two sides of the boom, I may be actually creating enough force to bend the sides of the boom inward. 

So far, I've been lucky (or there simply isn't enough force to damage the boom). Come Spring, I'll tie in my reefs on a windy day just like always. I'll go out there and then slowly ease them out (the #1 and #2) and see/feel the difference. Of course, I'll also play with the all-important choker and watch the sail. While my present approach has always provided a good-looking neat reefed sail, I look forward to seeing the results and knowing that I'm giving the equipment a well-deserved break (and doing it the right way, frankly).

One thing, Mark - the photo shows BOTH reefs actually tied in, while I was sailing with the #2 reef. This left the #1 clew in a sort of odd "pulled" state. I think that if only the #2 clew reef was actually tied in, maybe the rest of the sail would have laid there quite neatly.

Anyway, I can't wait for Spring.

Ernie A. in Toronto

[Thor (26C Brentwood Bay BC)]

1 foot above and 1 foot fwd of the cheek blocks ,that’s the rule Botts used 

[Mark Powers La Reina 26C Vancouver, B.C.]

Erine, as I said, I don't know if you will be able to achieve the Botts' Ideal with the cut of your current sail. The good news is you have not bent your boom so far so so there may no be enough force involved to bend the boom.

I am not sure have both reefs tied in will change anything. 

Mark Powers

[Bob Neches (Me Gusta, Nonsuch 26U #233)]

I've been thinking about this for a couple of days, and wanted to chip in with a question and a comment.

The question.  It's been 50 years since my college physics on static and dynamic load vectors.   I'm wondering if there's an engineer among us who could comment on the concern about the force of the sail pulling on the aft reef line being sufficient to actually bend the curved aluminum tubes that form our wishbones.  My guess is that the amount of force required would probably tear the sail or pull out the reef clew cringle before the booms bent.  Is there an engineer in the house who could speak to this?

The comment.  I was always taught regarding conventional sails that the key issue is maintaining sail shape by ensuring that the forces on the sail clew were approximately equally distributed horizontally along the foot and diagonally along the leach.  So my guess is that the advice about how close the reef lines should draw the reef clew to the wishbone is really more a rule-of-thumb.   I think it serves as a stand-in for making sure that the clew's positioned right relative to the wishbone to help in maintaining sailshape.  A bit above but relatively near vertically, so that the weight of the wishbone can do its job as a vang.  Relatively near horizontally so that the choker can do its job; the further away the clew is, the further back you'd have to pull the choker to keep the sail from balloning out rather than flattening down. 

Between the wishbone, the choker, and the topping lift, there's probably enough adjustability to make up for minor differences in how tightly the reef clew's pulled in.  Getting the reef clew positioned as suggested by others in this thread does minimize the need for tweaking them, though.

My $0.015 (originally two cents, but nothing's worth what it used to be).

-- Bob

   Me Gusta

   Nonsuch 26U #233

[Paul Miller]

I’m not an engineer Bob but I am a builder and I can’t see how anyone would mount the cheek block vertically on the inside of the boom if the reef line was was to be pulled tight back and near horizontal. It would seem to me that that alignment would dictate that the cheek block be mounted horizontally on the top  of the boom or at least moved in that direction to split the difference. Given that they did mount it inside the boom I can only conclude that the intended lead to it is from forward.

As for the boom bending force, when you approach horizontal that is up to how strong you and your winch are, not just the pull of the sail.

As I said, not an engineer… 

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[Ernie Abugov N22 - #56 "Moustaches" Toronto]

IMHO, both of you guys are dead right. The cheek block is not well positioned and, possibly, should be a floating block, maybe lashed to the boom such that it could assume the best position, always. I will try this approach (when the snow goes away and it's not -20 degrees C. It's (sort of) the same conundrum that exists with the choker cheek block high up on the mast. I, and others, have tried (and maybe stuck with) a floating block that is attached to the original choker cheek block but floats a bit forward of the mast. It will always end up in the optimum position.

Damn cheek blocks .......

I'm not a builder or an engineer but I did love high school physics. In my heart of hearts, considering how far back the reef cheek blocks are, I am having a hard time imagining that normal forces in a REASONABLE wind (not a roaring gale or worse) would actually bend curved aluminum the wrong way. I think that Bob is correct in assuming that lots of other things would fall apart before the boom even thought of bending.

But, hey, what do I know ???!!!!

Ernie A. in Toronto (where it is not nearly as cold as Maine)

[Bob Neches (Me Gusta, Nonsuch 26U #233)]

Paul did have it right about the amount of damage one can do overtightening lines with a winch, though.

On the other hand, I've never found myself needing a winch when reefing.  Can't speak for the bigger Nonsuches, but at least in my experience, hand tightening gets the lines where they need to be as long as the sail's at an angle to the wind which takes the pressure off, the topping lift's a bit up, and the choker's a bit eased.

-- Bob

   Me Gusta

   Nonsuch 26U #233

[Ernie Abugov N22 - #56 "Moustaches" Toronto]

I've never put my reef lines on a winch but I do understand that, on something bigger than an NS22, one may need to do that. I'd be careful, though. You can do some damage. I just daysail. If I got caught in something such that I had to use a winch to reef ..... I wouldn't. I'd go with a less-than-perfect reef and put in to port ..... any port.

Ernie A. in Toronto

[Mark Powers La Reina 26C Vancouver, B.C.]

I am not an engineer nor a sailmaker/rigger so I am not arguing with Botts. I would have thought the threads in boom for the screws or rivets holding the turning block to the boom would be the first to give up.

The calculation of force need to bend the boom is probably very complicated. The boom is curved so gains some strength from the curve. The pull of the foot of the sail on the heel of the boom will (I think) try to increase that bend by compressing the boom. However, the arms of the boom are relatively straight as you move back along the boom so I am not sure how that would be taken into account, The aluminium alloy used in the boom would have to be know, along with the diameter and the thickness of the tubes. The latter two might be easier to determine.  Here is a link to a calculation on the ability of aluminium to act as a beam.  The load will change as the wind force picks up. Wave action will likely cause shock on a regular basis. Sort of like jumping up and grabbing the monkey bars. 

https://engineering.stackexchange.com/questions/10957/how-much-weight-can-an-aluminum-tube-beam-support

Have to say I can't do the math. I don't even know what all of the symbols mean.

I have only heard of one Nonsuch boom failing and that was a carbon fibre boom on a 260 so the odds of one failing are not great. 

Mark Powers

[Mark Powers La Reina 26C Vancouver, B.C.]

A number of years ago Ed Botterell made a sail for me. I was having a difficult time getting a proper shape when I reefed the sail. I met up with Ed to discuss the problem while I was in Toronto on a business trip. Another owner of a 26 in the Toronto area was having the same issue. Ed was going to the boat for a test sail and invited me along. 

We headed out on to the lake in about 20 to 22 knots of true wind. The skipper asked Ed "First or second reef". Ed replied "I don't want a reef, I want to see how the sail sets first". So full sail, full choker and off we went close hauled with the rail often dipping into the water. 

Satisfied with the sail shape (it looked nice) Ed told us to put in a reef. I could only get the reef cringle to with about 3 feet of the boom. The sail below the cringle was blowing up over the top of the boom. Ed said grind it the reef line in. I asked how hard. He said as hard as you can you won't hurt the sail. I was able to grind in about another 6" of line. I was sure the cabin top was starting to deform. Ed figured I was not trying hard enough so he stepped in. I am happy to report he could not pull in anymore line than I had. 

Turns out even with the choker full slackened off, you can't lift the boom with the reef lines. We were using the small cabin top winches with a 10" winch handle. The solution was to shorten the standing part of the topping lift so the boom could be raised higher. 

We did not have to worry about bending the boom because we were not where close to having the reef line pulling straight across. 

An old sail might not take kindly to that much force.

Mark Powers

[Thor (26C Brentwood Bay BC)]

interesting fact. If your main sheet breaks at the boom, you can regain control via the reef line.  Happened to a friend with a 30 and that's how he regained control

[Ernie Abugov N22 - #56 "Moustaches" Toronto]

You got me here, Thor. The boom is way off of one side of the boat and the mainsheet snaps. Bang !!  The clew reef line runs along the boom to the front of the boom and down the mast and back to you. Short of pointing the boat in the wind (which may be the solution, actually) how do you "regain control" ?? Undo the whole reef line from the boom ?? If so, why not just retie what's left of the mainsheet to the aft end of the boom ? Neither way will you have a double purchase - you'd just have a single line.

Am I being clear ??    I do wonder .....

Ernie A. in Toronto

[Thor (26C Brentwood Bay BC)]

It's not pretty, but there is enough purchase off the reef lines to corral the boom and hold it more or less mid ships.  You're not sailing at this point just regaining control of the boom.  Once the boom is more or less centred you can then fix it or tie it down.

[Ernie Abugov N22 - #56 "Moustaches" Toronto]

Gotcha, Thor.

Ernie A. in Toronto