4:1 Cunningham ?

Moderator: GreenLake

4:1 Cunningham ?

Postby RobH912 » Sun Sep 08, 2019 8:54 pm

My boat did not come with a Cunningham set up and last several weeks I have just tied a line through the cringle, bowlines knot tied below the boom, and run this line through a small deck block to a cam cleat. The block and cleat set up are for the spinnaker foreguy line. Looking for a better solution.

Searched the forum but didn’t see any specific DS1 Cunningham set ups.

Found this diagram on the Harken web site showing a 4:1 setup. I understand Harken sells hardware, and was wondering if this 4:1 setup is “right” for a DS1?

Also the diagram shows the line attached to the mast. Any advantage to attaching to the mast rather than to the boom?

I’ve got this “mystery” green line coming out of a hole on the bottom of the boom and thought I might get rid of this green line, start the Cunningham line here, up and out the cringle, to the single block marked “A” on the Harken diagram.

Appreciate any thoughts / comments.
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Thanks!

Rob

DS1 #14061
Cape Cod
Eastham, MA
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Re: 4:1 Cunningham ?

Postby GreenLake » Sun Sep 08, 2019 10:56 pm

Rob, I have a 2:1 operated at the mast. There's a horn cleat in the sail track below the gooseneck which is used to belay the line that holds the boom down. I make that cleat do double duty. My Cunningham ends in bowline on one end, that gets hooked over the horn cleat, and the other end gets pulled tight and then belayed. A simple upgrade would be to use a dedicated cleat below the first one. The location in the mast track is better than the eye shown in your schematic because it doesn't change geometry when the boom swings.

Now, I don't adjust the Cunningham very frequently, usually set it once (for a one hour evening race). Maybe I should do it more often? No idea; usually too busy with other things.

However, 2:1 seems fine (but I'm not losing anything to friction from routing things back to the cockpit).

Can't give you advice on your mystery line, because I'd have to look at your boat to form an opinion.
~ green ~ lake ~ ~
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Re: 4:1 Cunningham ?

Postby jalmeida51 » Mon Sep 09, 2019 9:43 am

Rob, My Cunningham attaches with a 1/4 line from a eye strap that is attached on side of the mast thru the reefing cringle to a Harken 29mm single block Harken P/N 340. On the same side of the mast below the single block I have a Harken P/N 395 Pivoting leak block with a cam cleat. This is attached to the mast. I used 5/16 line for the running line. It was a tight fit securing the line thru the becket of the pivoting block. Harken calls for 1/4 line but I had a line of 5/16 at home. If I get down to the boat today Iwill try to send you a picture. John
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Re: 4:1 Cunningham ?

Postby tomodda » Mon Sep 09, 2019 5:15 pm

Rob:

Just to confuse things, I don't use a Cunningham at all, I have a boom downhaul. I have a 2x1 cascade pulling the boom down the mast track at the gooseneck. I'm using 2 single bullet-type blocks and a turning block at the deck to lead back to a cleat at the edge of the cuddy, I like all my controls there.

Why boom downhaul? Because IMHO the traditional Cunningham throws unwanted wrinkles into the mainsail, especially at the foot but also diagonally out from the tack. The Cunningham was designed to tighten the luff without pulling the boom lower than Band 1, as set in the Class Rules. Since I'm not racing, I don't care about following the rules (as long as I don't do anything that cant be put back to class rules later), so I elect to pull the whole luff down via downhaul. In practice, I only wind up going 3-4 inches below Band 1 anyhow - I put some tape on my mast at the right point, just for reference. If I ever want to race in Class-legal race, I'll just re-route the cascade to go thru the Cunningham cringle, no big deal.

So.. if you are not racing in a class event, consider just rigging a boom downhaul. Simpler to rig and a cleaner sail shape.

Best,

Tom
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Re: 4:1 Cunningham ?

Postby GreenLake » Tue Sep 10, 2019 1:50 am

Tom. That's interesting. However, in my case, if I were to go 3-4 inches lower, I would remove needed room for the vang to have a reasonable angle. For that reason alone, my boom downhaul goes to a fixed location (I've never tried to sail with the boom higher than the stop at ~ band 1). My Cunningham has a dedicated cringle, which is much closer to the boom than the first reef. I've not observed any sail shaping issues, because the last few inches above the boom are a compromise anyway if you don't have a loose-footed main. The "shelf" built into the sail to allow camber while at the same time fixing the foot of the sail in the (straight) boom slot does not seem to me an aerodynamically clean shape.

I also don't have experience with fine tuning the Cunningham in very high winds, those tend to be rare for our evening races (non class-sanctioned, so I'm also not worried about class rules). As a result, I don't know whether sail shape issues would be worse, or whether I would ever need more than the simple 2:1.

Do you find you play with it (your downhaul, since you don't have an actual Cunningham) a lot?
~ green ~ lake ~ ~
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Re: 4:1 Cunningham ?

Postby RobH912 » Tue Sep 10, 2019 7:53 am

Thank you all for your responses.

LOTS of good information and thoughts... It will take me a little while to decipher it all and maybe draw out some sketches.

John thank you for adding the Harken part numbers!

Tom so your goose neck must be on a track for the boom to be pulled down the mast track? My gooseneck is fixed to the mast. I have seen using the ad hoc solution described in my post that I do get some wrinkles in the sail, at the foot of the sail along the boom near the tack.

Let me work on this some.
Thanks!

Rob

DS1 #14061
Cape Cod
Eastham, MA
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Re: 4:1 Cunningham ?

Postby tomodda » Tue Sep 10, 2019 7:57 pm

Hi Folks!

Answering:

@RobH, yes my gooseneck attaches to the sailtrack on the back of the mast - it slides into a section that is a bit wider, same thing I use to bend the sail to the mast. Except for the slot portion, it can go as high or low as I want it. Occasionally I put it up above the slot (and pull the clew end up with my topping lift) just to get everything way up out of the way if I'm motoring. Yeah, boom downhaul wouldn't work if the gooseneck can't move up/down. For what it's worth, the wrinkles at the foot of the sail don't really matter, that whole area gets more turbulence than anywhere else on the sailplan. My mainsail is pretty much an old bag, so I'm more interested in getting that diagonal crease out, and moving the max draft point forward, which you can do with a "normal" Cunningham as well.

@GL: My geometry works out for the boom downhaul not interfering with the vang. As I wrote somewhere else, I use a 20:1 vang setup and it attaches to the boom about 3 feet back from the mast, so enough space. How often do I adjust the downhaul? I'd say about 3-4 times per outing. I try to trim the sail to not have "bad" wrinkles (see note) and get the draft where I want it. Also I don't have reef points, so if I need to depower it has to be via sail shape (and luffing and eventually dropping the jib, ugh). As the wind gets stronger, I crank down on the downhaul - and outhaul, and vang - at least when reaching or beating upwind. When I come off the wind - broad reaching or running - I'll ease the downhaul again, outhaul too depending on wind speed, so the draft deepens and moves back towards the leech. I'm still playing with vang steering, so how much I use the vang vs downhaul all depends. Anyway, since my usual afternoon's sail is upwind as far as I feel like going then run home, that means only a few adjustments to the downhaul. I'll also slack the downhaul/outhaul as the wind dies down.

Perversely enough, in near-drifting conditions, ghosting along, I tighten up the boom downhaul again and give it some outhaul, at least upwind. Sometimes I'll also pull the clew up with my topping lift, anything to get a "clean foil" into the little wind that I have. I don't want to waste any wind energy shaping the sail, so I shape it with my "strings" and hope for a puff. Does it really make a difference? Jury is still out, hard to tell with no GPS, but it gives me something to do besides whistling for more wind!

Lastly, answering obvious question - where do I want the draft? Judging the distance from luff to leech, I want it about 40% of the way back most of the time when beating or reaching, further back 50-60% in lighter air (maybe <8 knots) or running, further forward 30%-ish for heavier winds (for me, that's >20 knots), back to 40%ish for ghosting. I plan to put a draft stripe on my sails one of these days, but for now I just eyeball it by staring upwards with my head as near to the boom as I can get while also steering and tending the sheets. Basically, I'm winging it! Not racing, so it's just for fun anyway. In practice, I'm usually sailing along and wondering why the hell I'm so slow when there's a decent wind and everyone else is zipping along... then I remember that I left the draft point way the heck back and need to tighten the downhaul. Or else it's something completely different I'm screwing up, usually sail twist :roll: . Tune a few things, hike my butt out further and she's humming along again! Call me crazy, but I enjoy chasing after that elusive "perfect sail run."

Note: No marconi-shaped dacron sail is ever 100% wrinkle free, see this: https://www.northsails.com/sailing/en/2 ... nkles-fast

Best,

Tom
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Re: 4:1 Cunningham ?

Postby GreenLake » Tue Sep 10, 2019 9:55 pm

nice summary.

Your low wind strategy sound right to me, there's a realm where you need to take camber out of the sail, or the flow won't remain attached. When I get that right, I do really well . . . usually that's when I also heel the boat to leeward to reduce wetted surface.

I find that with vang on, I can depower much better by letting out some main. The reason, of course is that the vang maintains the flat sail shape. But it's nice to see that in action. Vang ir relatively new on my boat, so there are other conditions that I haven't dialed in as well yet. Had mainly race events this year and those can be insanely busy with boat traffic, mostly bigger boats, which makes it fun, but also very distraction and not a good time to spend tinkering with sail controls.
~ green ~ lake ~ ~
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Re: 4:1 Cunningham ?

Postby jalmeida51 » Wed Sep 11, 2019 11:45 am

I am thinking of installing a Cunningham hook on my Cunningham tackle. Right now I have a fixed line attached to the side of the mast thru the Cunningham cringle to a block. Like the above Harken sketch. I could remove the Cunningham and use it to help me reef the luff. Right now I use a reefing hook at the gooseneck. I find it hard to get the reef cringle thru the hook in a stiff breeze due to the main luffing and sail being crisp. I believe by using the Cunningham I will get a flatter main. I can get more tension on the luff instead of just using the halyard. Any thoughts on using a Cunningham hook? Thanks, John
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Re: 4:1 Cunningham ?

Postby tomodda » Wed Sep 11, 2019 3:53 pm

John:

Let me see if I'm understanding you correctly. You have your cunningham rigged up like so (this is also how I had mine before I went to a boom downhaul):

cunningham_grootzeil.jpg
Cunningham
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You are proposing to put a hook at the end of the red line and just hook into the cringle, not go behind the sail (dotted red line)? I can see the advantage of being able to use it as a reef hook - I'm assuming you have a reef cringle higher up the sail and closer to the luff. Just swap cringles and pull. Is that what you have in mind?

If that is what you are planning, I see a few problems:
-You're going from a 4-1 purchase to simple 2-1. You may or may not need personally need 4-1, but it helps.
-Man,for reefing that's an awful lot of stress on the cam cleat and on the hook itself. Maybe use a horn cleat instead of cam? Just seems risky to me, I like to have a large margin for error on my reefing gear. Says the man with no reefing gear on present boat.
-And just think thru the steps.. as opposed to working on the cunningham, for reefing you also have to slack the main halyard. So, how's it going to work? Move cunnngham hook to reefing cringle, slack halyard, pull on cunningham-turned-into-reef-line, tie down halyard, tie down cunny/reef line? My own cunningham cascade tends to turn inside out and upside down if not under tension (line pops out of the block the wrong way around), you can quickly get a tangle if you are not careful. All this while the wind is blowing hard, you're in irons, boat is bucking short waves, rigid sail is luffing hard. Will it work or are you better off with a dedicated reef line? Or is that overkill for a 17-foot boat? Where will you be sailing.. a place with short steep waves or longer fetch? A place where you can see the bad weather coming in from miles off or it comes up suddenly and unseen? Do you wait till you are in a blow to reef or do you reef early and often? How strong are you when tired, cold, and scared?

Anyway, I'm not saying it's a bad idea, just to think it thru. Cunningham hook is cheap, buy one and experiment in non-emergency situations. If I remember, you are in Florida, you get squalls, you can see them coming, it's not that cold. If you have adequate time to reef, you should be OK... assuming that the whole tackle will hold (I'd worry about cam cleat slipping).

All the best,

Tom
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Re: 4:1 Cunningham ?

Postby jalmeida51 » Wed Sep 11, 2019 9:30 pm

Tom I have set up my Cunningham different than your sketch. I have a block where I'm going to disconnect the red line from it. Add a reefing hook directly to the block and the running line will go down to a pivoting lead block with cam cleat. This pivoting block is attached to the side of the mast. All the hardware on the cabin roof on your sketch I will not need. I have 3 cringles on my main, Cunningham, 20% reef, 40% reef. ( luff ) I reef now by using a reefing hook on the gooseneck for the luff and a dedicated reefing line for the leech. It works but I would like to get the main flatter. Plus getting the cringle hooked on can be a pain. I talked with a sailmaker today and he suggested to use webbing with a D ring attached to the reefing cringles. This would make it easier to hook it to the gooseneck. This would solve that problem, but I still can't get the main flat just by using the halyard. Maybe I'm being too fussy about the flatness of the main.
I won't splash the boat until the tropics clear up, 3 more tropical lows have formed and 1 is heading towards Florida in a few days. Might become a tropical storm after it gets out in the gulf. I have time to figure on which system I'll use.
Thanks for all of your ideas John
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Re: 4:1 Cunningham ?

Postby GreenLake » Wed Sep 11, 2019 11:06 pm

Jim, if I understand your concern correctly, your real problem is insufficient halyard tension; you would like to fix that by pulling on the (new) tack.

A number of simple solutions, assuming that you change your reef grommet to a web strap with D ring. First one would be to put a loop or handle on the strap so that you can apply all you've got to pulling down the sail and hooking the ring over the hook. (Assumes, you've locked your halyard at a good position for ultimate tension).

Second, a dedicated strap with handle/loop that runs from the boom through the reef cringle. You operate the same way, but now you get a 2:1. Again, this would require a bit of precision in setting the halyard, but I assume you could mark the reefed position.

If you find it difficult to pull down at that position, lead the rope through an eye on the deck so you can pull up. None of these involve blocks, so you shouldn't have an issue with things tangling.

How is your halyard belayed? If it's on a horn cleat, I can see that treating it as "fixed" is the better option, but if on a cam cleat, you ought to be able to pull sideways on the halyard and then take the slack out of it as you let go. That sideways pull is easily a 10:1 purchase, and even if you lose a bit of the tension as you take the slack out at the cleat it should be able to hold its own against tightening the reef line with a 2:1 or even 4:1.

If you are worried about a cam cleat giving way you could mount a rope clutch or just put on in line above your horn cleat.

About the use of hooks: I'm using a hook for my jib-halyard tensioner (because it's attached to the halyard via a Prusik loop into which I hook). Hooking it up after belaying the jib halyard on its horn cleat is simple (as long as I don't trap any other lines between it and the mast) and the hook holds well (even if I release tension on it when running under spinnaker - when I re-use its cam cleat for my downhaul). So, from that experience, I'd see a hook as possible but would prefer a setup where it's use is temporary - during tensioning or where it has a backup.
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