Cunningham?

Ed Schenck · Apr 16, 2008

Fixed gooseneck?

I know nothing about the Mac 25. But your query suggests that the boom is fixed, that the gooseneck does not slide. My old C-22 had the cunningham attached to the boom. The gooseneck was on a slide so that you could tension the luff that way.

dancing bear · Apr 16, 2008

My 1986 M25

Has a fixed gooseneck and no accomodations for a cunningham at all.

Joe · Apr 16, 2008

Yes, install a cunningham cringle.... it won't work with the reef point.

For clarification: A downhaul pulls down on the gooseneck which is on a slider in the mast track. A cunnigham pulls directly on the sail's luff. Have a cringle inserted in the sail if the the gooseneck is fixed. In any event, rig at least a 3:1 purchase so you can work it without using a winch. With a reef hook on a pendant rigged to the blocks, you could use the cunningham for the forward reef line, if so desired.

Joseph Shirley · Apr 16, 2008

Joe (the other one) is correct. You don't see many sliding goosenecks any more

but they are a little better but more expensive than fixed goosenecks; because in addition to using them to tighten the luff tension, you could lower the center of effort of the main, sometimes eliminating the need for a reef. It also lowered the boom to make it easier to reef, and even to furl the main on boats with a high boom. They fell into disfavor, like so many good ideas, because of racing rules. Since you could stretch the luff oversize it was stretched at the time of measurement and you carried that penalty all the time, even though you normally sailed with a shorter luff. Going to the fixed gooseneck with the cunningham (actually innovated by Briggs Cunningham the race car driver), fixed the luff measurement at the nominal so the luff was the same no matter what the luff tension was.In the absence of a cunningham cringle, you could use the 1st reef luff cringle, but it wastes more mainsail shapeand is not recommended. If and when you can afford it, take the main to a sailmaker, and have him put a cunningham cringle in it. It should be done by a sailmaker because the sail has to be reinforced to handle it.Joe S

Alan · Apr 16, 2008

As an alternative

My main has no 'fixed' tack. The tack sides freely in the mast grove and the cunningham control line is run the the tack cringle. The 'floating' tack will only work for loose footed mains, however.

Joseph Shirley · Apr 17, 2008

You may have enough main halyard hoist left to

tighten the luff by tightening the main halyard. The cunningham is designed to tighten the luff to flatten the main. That assumes (as I did) that the main is hoisted fully to a stop, as is sometimes required in one design racing classes, or to a black band required for racing. If you have neither, you may have enough room at the top of your mainsail hoist, to just heave around on the main halyard. It's easier to pull down on a cunningham than to pull up on the halyard, but its an alternative solution to flatten the main without putting in the cunningham.Good Luck Joe S

RichH · Apr 17, 2008

Install the cunningham cringle.

If your gooseneck is 'pinned' (not on a sliding downhaul), you will need a cunningham cringle and its associated reinforcement patches. A cunningham is typically for a boat your size approx. 12" (or less) up from the boom. Tightening the halyard will only draw the draft forward in the top portion of the sail (as the friction in the luff sleeve on the boltrope wont 'equilibrate' all the way down the luff) and this will have little effect on the draft position in the lower/bottom panels. The cunningham better pulls the draft forward in the bottom panels and not much affect at the top/head. Using the first reef cringle position as a cunningham will make the draft go forward in the panels above the cunningham .... but but but will INCREASE draft and allow the draft to go aft in the lower sections. Adding a cunningham cringle and its reinforcing patches is a simple and quick job for any sailmaker. But the important questions is: do you know why/when/how much to tighten a cunningham? The adverse effects of cunninghams are: makes the luff section more 'rounded' and thus makes the sail more unstable for 'backwinding' (not a true term but everyone uses it, so will I) by a large jib/genoa. So, on a boat that doesnt have 'athwartships' (side to side) adjustment for the jib/genoa fairlead cars a cunningham may not be what you are looking for. The more cunningham tension you apply, the more you have to move the jib 'away' from the mainsail or 'you have to open the distance in the 'slot' more .... because the luff gets 'rounder' in shape. So, the next question becomes: why do you need a cunningham? Why I use a cunningham is to move the draft forward in the bottom portion of a mainsail .... so that I can move the point of maximum draft (forward) to obtain the correct amount of (weather) helm pressure I desire .... and also to slightly 'depower' the lower sections of the leech (to correct for a leech that is 'hooking to windward' when Im aggressively tightening the mainsheet). Why do you need a cunningham? ;-)

Joseph Shirley · Apr 17, 2008

Rich, What kind of BS are you sprouting?

I agree that "Adding a cunningham cringle and its reinforcing patches is a simple and quick job for any sailmaker." and I do not recommend using the reef cringle, but beyond that its BS.You said: "Tightening the halyard will only draw the draft forward in the top portion of the sail (as the friction in the luff sleeve on the boltrope wont 'equilibrate' all the way down the luff) and this will have little effect on the draft position in the lower/bottom panels. The cunningham better pulls the draft forward in the bottom panels and not much affect at the top/head. " ----and that is just not true. The halyard pulls the whole luff tight and not just the top, and the cunningham does the same thing by pulling down , not just the bottom panels as you said. If you have so much friction in your sail slugs, bolt rope or slides, depending on what you have, that your luff doesn't equalize, you better get that fixed.That business about backwinding the main and the cunningham just moving the draft in the bottom of the sail doesn't make sense. The cunningham pulls the draft of the whole sail forward and flattens the main, and reducing the draft in the entire sailYou said: " The adverse effects of cunninghams are: makes the luff section more 'rounded' and thus makes the sail more unstable for 'backwinding' (not a true term but everyone uses it, so will I) by a large jib/genoa." ---and the truth is just the opposite. It flattens the main and makes the luff less rounded, and as it does that it opens the slot and decreases any back winding or the main that may have been happening.,---and you don't have to more the jib leads outboard, you can tighten the jib halyard and move the draft there forward and flattening that sail.--and then you say: "The more cunningham tension you apply, the more you have to move the jib 'away' from the mainsail or 'you have to open the distance in the 'slot' more .... because the luff gets 'rounder' in shape." -- If the sail is getting flatter and the luff is getting tighter, how does the luff get rounder? I didn't want to get confrontational with you but I can't sit quietly for that kind of stuff.Have a nice dayJoe S

newly anonymous · Apr 17, 2008

hmmmmmm....

...many older bolt-rope leaches worked exactly as RichH described, while more modern setups, such as a batt-car system, behave as Joseph suggests. But let's not forget that the cunningham does more than just move the draft forward; it also serves to flatten the sail. It tends to do this better than the halyard because the halyard is at the skinny end of the sail. What this means is that halyard tension will tend to close the leech, while cunningham tension tends to keep it open. And that's a good thing, if you want to go fast.

RichH · Apr 17, 2008

BS ..... you're all bassackwards. $$ Bet is offered.

OK since you want to be confrontational. Ill be confrontational right back at you. ;-) A cunningham does NOT flatten a sail as a principal function. With respect to WOVEN dacron sails, Take ANY piece of triangular cloth, pull on one edge and SEE what happens. The tensioned edge gets longer and 'curls' and the opposite side 'opens' or releases. I'll stick with what I stated. A cunningham **MOVES the point or position of maximum draft**... more cunningham and the PT.oF Max draft goes forward, release the cunningham and the draft goes aft in the sail. When you over tension the luff via a cunningham or halyard the LEECH trips open and that gives the 'impression' of a flatter sail.... but unless you pull the outhaul you dont get a flatter sail, just a sail with draft that moved FORWARD. Maybe you dont understand how a cunningham works and dont realize that a cunningham only affects tension in the sailcloth but not the preloaded boltrope at the luff as the sail above the cunningham is free to slide (less friction) in its sleeve and has little effect (other than some friction) on the boltrope. The boltrope is directly connected to the halyard BUT the sleeve always has some friction and able to slide and that is 'distributively additive' as you go down toward the tack .... so the halyard tension does not act equally along the luff due to friction. I dont think you understand what the job of a boltrope is, nor the function of its PRELOAD when the sail is made. Halyard pressure alone will not act equally all down the luff ... as the luff sleeve will by friction distribute that load unequally all the way down the luff towards the tack; hence with respect to the sail cloth (not the boltrope which is stretching under more halyard tension) the strain on the sailcloth (luff sleeve) by the halyard tension will not be the same at the top as the bottom. .... Its all about friction of the boltrope versus its luff sleeve. Doesnt matter if the sail has slugs or its boltrope fed DIRECTLY into the sail track on the mast. The halyard connects to the BOLTROPE, the sail cloth is only connected in TWO places to the boltrope - twine stitching near the head and at the tack (woven dacron sail fabric) .... otherwise the luff sleeve can slide (plus friction) on the boltrope. That boltrope is characteristically cut 1" shorter than the luff length for every 10-11ft. foot of luff length ... and the sail doesnt 'move' much until that PRELOAD in the boltrope of 1"/10-11ft is stretched out of the boltrope AND the boltrope is stretched to the **same** or greater length dimension as the luff sleeve !!!!! *****Total BS ..... take any woven cloth sail and overtension one edge (via cunningham or halyard) as the effect will be to change the 'entry shape' of the luff from relatively flat to a more 'rounded shape' ... as the point of maximum draft goes FORWARD (closes the 'slot' in erroneous sailtrim speak). The roundness and the movement of draft forward takes SPACE .... aerodynamically the boundary layer flow becomes unstable due to the more 'roundness of the luff shape' and more easily separates from the boundary layer (separation stall) which is erroneously called 'backwinding'. So to compensate, one must either use a smaller jib (leech more 'hollow' to match the new shape of the mainsail at the luff OR move the jib/genoa clew OUTBOARD to regain flow attachment AT the luff of the mainsail. With a cunningham, the apparent flatness in the main is ONLY from the point of maximum draft rearward ... but that is due to the effect of stretching one edge (luff) which 'opens' the opposite edge. As the draft goes forward due to luff tension, you get more ROUNDNESS to the luff entry shape; sometimes when overtensioned to the extreme you will get a crease/'girt' running along the luff at the mast. BS!!!**** Overtension of the halyard (top of the sail) or cunningham (bottom of the sail) gives the appearance of flat but only FLAT in the sections AFT of the point of maximum draft (because it 'trips' the leech open ... go pull some triangular cloth pieces). Moving the draft ***forward*** adds that roundness to the LUFF section. Try it sometime and SEE what these controls actually do. If the sail is getting flatter and the luff is getting tighter, how does the luff get rounder? **** because you are moving the point of maximum draft forward, and in the extreme, you are causing a 'girt'/crease to form right behind the luff when overtensioned. I didn't want to get confrontational with you but I can't sit quietly for that kind of stuff. *** OK Ill get confrontational since Ive been cutting and making my own sails for 35 years.... and maybe understand a wee bet better of how a sail 'strains' into differing shapes when tensioned SOLELY along one edge. ***** A cunningham principally shapes (the draft POSITION) IN the bottom sections of a sail; the halyard principally affects shape (the position of draft) in the TOP sections of a sail. IF the boltrope was frictionless in its luff sleeve or the boltrope wasnt preloaded / shortened, or the boltrope was attached uniformly to the sail cloth all along the luff (it isnt), your argument would have a modicum of merit, otherwise what you state is FALSE. You have a gross misperception, sorry. ***** Pulling a cunningham to overtension only results in a flat sail AFTER or AFT of the *point/position of maximum draft* (which goes forward when the luff is tensioned) .... not in FRONT of that point of maximum draft which becomes more ROUNDED, etc. The luff becomes more rounded because you are *moving* the position of maximum draft INTO or towards the luff section. Especially on a non-boltroped sail the less luff tension the FLATTER the luff shape becomes. What may be confusing you is the action of that boltrope that adds its PRELOAD (shortened) dimension into the mainsail... and without that boltrope the luff would be extremely FLAT entry shaped (like what we do on ice boats and super-fast planing hulls). BTW to FLATTEN a sail -(to decrease the *amplitude* of DRAFT) one uses the *****OUTHAUL***** ... and does so without shifting the position of max. draft (forward or aft). If youve been trying to flatten by using the cunningham, you've been doing it all wrong !!!! When a sail is windloaded beyond its design (typically 12-15kts) the fabric stretches and allows the position of max. draft to migrate aft in the sail.... to reposition that max. draft position, you pull the cunningham which moves the draft back forward to its proper position (or increase the halyard tension which is more effective in draft position at the TOP). I suggest you cut up some cloth triangles and see what happens when you pull along one single edge .... 'cause you got it ALL WRONG. If you want to 'flatten' you use the outhaul; If you want to reposition the pt. of max draft use the cunningham AND the halyard. have a nice day yourself.

Joseph Shirley · Apr 17, 2008

Rich, you are changing your story

You originally said Tightening the halyard will only draw the draft forward in the top portion of the sail" and "The cunningham better pulls the draft forward in the bottom panels and not much affect at the top/head".I said "The halyard pulls the whole luff tight and not just the top, and the cunningham does the same thing by pulling down , not just the bottom panels," and "That business about back-winding the main and the cunningham just moving the draft in the bottom of the sail doesn't make sense. The cunningham pulls the draft of the whole sail forward and flattens the main, and reducing the draft in the entire sail."Now you are making the general statement saying "A cunningham **MOVES the point or position of maximum draft**... more cunningham and the PT.oF Max draft goes forward, release the cunningham and the draft goes aft in the sail." -- That's more like what I said than what you saidNow when the draft does go forward it comes from somewhere and that is what helps to flatten the sail.Then you give a bunch of literary dialog about the bolt-rope and its friction, the luff section being rounded, making the sail unstable for back-winding, the necessity of opening the slot by moving the jib away because the luff is more rounded is all superfluous BS. Who are you trying to impress?Lets talk about the luff. You sound like you are trying to be convincing by the volume of your explanation. Most cruising boats use luff tapes instead of a bolt-rope and they are secured to the mast by slides or slugs which are supposed to slide easily in the track , or on the track, or in the slot with negligible friction. When a bolt rope is used it is sized so that it too has negligible friction. They are all designed to minimize any residual vertical load on the sail while holding the sail against the mast. Any discussion about sliding the luff to stretch it, from nothing at the fixed end, to a couple of inches at the stretching end, should discount any friction in the luff as it is meaningless. Your preoccupation with this friction creating any noticeable difference in the stretch at one end of the luff to the other is preposterous.You also said: "When you over tension the luff via a cunningham or halyard the LEECH trips open and that gives the 'impression' of a flatter sail.... but unless you pull the out-haul you don't get a flatter sail, just a sail with draft that moved FORWARD."---= and that is correct, but the thing of it is, that you should have already tightened the out-haul before you added some cunningham, and under these conditions the sail would flatten.My friend I know how to use a cunningham as well as you, so I don't need your descriptions of triangular pieces of cloth and bolt rope friction, open or closed leaches,rounded luffs, opening the jib slot, and the adverse affects of the cunningham to discuss installing a cunningham with someone who asks a simple question. I gave him a simple answer and then provided a simple alternative to use until he got the cunningham. You also gave him the same simple initial answer followed by a false explanation of why the alternative I gave him wouldn't work, and then a snow job about how you use a cunningham. Asking why did he need a cunningham. I thought it was BS then and still do. You used that point about opening the slot by moving the jib outboard without discussing that you could accomplish the same end by moving the draft in the jib forward by just tightening the jib halyard, if that point had any relevance to the question at hand. It appears to me that you are now doing more of the same.

filthy liberal scum · Apr 17, 2008

rich is correct

what hasn't been said here is that the need for a cunningham depends a lot on the luff length of the main. i don't know the specs on a mac 25 but it may have a small enough main that its not needed. i do know that on my O'Day 30 that if i did'nt have a cunningham i would not be able to move the draft forward in the lower half of the main with halyard tension alone. it just plain won't happen. there's too much material and weight to tension it evenly from the top to bottom with halyard tension alone. so conclusion is draft forward more cunningham. to flatten the main use more outhaul. I was taught by one of the best sailmakers/sailors in the world. Max Skelly,world class J-24 competator, Lazer world class also. I would suspect he just might know what he's talking about.S/V Que Pasa?

Sandy Stone · Apr 18, 2008

I'd add one comment about sliding goosenecks

only because the subject was brought up below. I owned a boat with one (Pearson 26OD) and found that the interaction with the boom vang was always a nuisance. In other words, if you tightened the downhaul the vang would go slack, eased the downhaul the vang got tight as a piano wire. I much prefer a cunningham.

Tom S · Apr 18, 2008

Wow. A real Sail Trim discussion on a Sailing BB

Who da think it !

Its funny I kind of see both sides of each persons Point Of View

CharlieCobra · Apr 18, 2008

Nah, it may have started as one

but it degraded into the typical s-fight seen up here these days.

Ross · Apr 18, 2008

Charlie, Have you noticed that sometimes a nice

clear concise question that could be answered with about four sentences gets four paragraphs from some people and still doesn't answer the question?

Taylor · Apr 18, 2008

Both these guys...

... have a lot to add. I've actually learned quite a bit reading both points of view, and I appreciate the effort made and the passion. I did not realize that the tension from the halyard was taken by the bolt rope (or equivalent) and I had not thought that the cunningham acts on the sailcloth but not on the bolt rope. Its true that my cunningham experience is on a dinghy with a bolt rope in a slot (lots of friction) and a halyard lock (no halyard adjustment) at the top and a black band. On the other hand, I had not really thought about how a sail with luff tape and slides on my big boat might act differently that one with a bolt rope on my OK Dinghy. Plus - I did not know that the bolt rope was not fixed to the sail all the way along. So in short - Joe, Rich - you guys rock - get together and I'll buy the beer. OK?

LANCE ON CLOUD NINE · Apr 18, 2008

Hey Taylor- Man I could not agree with you more.

I have not yet read all of Joe's postings but am looking forward to it. But I gotta tell ya, RichH has NO IDEA how much enjoyment he has contributed to my sailing. After I bought my little O'Day 23 (in fantastic condition, but I never sailed it before purchase) I could not believe what a dog it seemed to be. I just assumed I needed a bigger boat to go a little faster. But what I needed most was a little more knowledge to get more efficient and get the most from what I had. Just getting my halyards and out haul cinched up, made it feel like a completely different boat. And shaping sails for "1st gear wave punching power" to flattened for 3rd gear overdrive speed has made a huge difference. I know alot of this is obvious to people who grew up sailing but I started at ground zero and middle aged. To be able to quickly absorb this quality information over the internet just because somebody chooses to help us is a pretty special situation. Yep, they rock!