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Sucia

Using Runners & Checkstays on Masthead Rig

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I searched last night on this and didn't find a great deal of clear information on this for my specific situation - so here goes.

 

My Boat: C&C 34/36R

My Rig: triple spreader, mast head with a backstay with inline hydraulic adjuster, runners & checks. The runners terminate midpoint between the top and middle spreader, the checks terminate at the midpoint between bottom and middle spreader.

 

My current assumptions:

Light Air: little or no tension on backstay, and runner & checks. Want nice luff curve on jib, and full main for full power.

Mid Air: tension backstay as wind builds to flatten luff curve in jib and increase pointing, tension runners/checks to take bend out of mast and make a fuller main for more power.

Heavy Air: tension backstay hard to depower jib and increase pointing; keep runners/checks tight but not fully tensioned to put more bend in the mast to flatten main to keep from being overpowered.

 

I'm currently leaving the checkstay adjustment (a small 6:1 or 8:1 tackle attached to the same shackle as the end of the runner) fully extended and not really adjusting it - since truth be told - I'm not sure what it's supposed to do. Kinda scary, I know - that's why I want to learn.

 

 

Questions:

With a masthead rig, what specifically do the runners do? what specifically do the checkstays do?

I've read that the runners control jib luff tension primarily, and checkstays control bend of the mast to control the main's luff curve - although this seemed to apply to fractional rigs where the runner terminated at the forestay height.

 

In middle wind conditions, when I want a full main for power and moderate jib luff tension for pointing, should I be tensioning the checkstays more than the runners?

My current assumption is that I should provide moderate backstay tension then plenty of checkstay tension which will likely leave the runners a bit loose but will take out the lower curve of the mast.

 

 

Educate me please. No need to be gentle. I just want to get faster.

 

Any advice is appreciated, as well as links to tuning guides for boats with rigs like mine with runners and checkstays.

 

Thanks!

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Both contribute substantially to mainsail shape. The more flexible the rig the more important they become and some of the moves with a masthead rig are counter intuitive. Assuming a reasonably flexible rig as you apply increasing backstay pressure you are not only pulling backward thereby increasing headstay tension (good for heavier air) you are also compressing the rig causing it to bend (resulting in a flatter main) again good for heavy air BUT compression shortens the distance between the bow and headstay resuting in more headstay sag (bad for heavy air and pointing. So use your runners and checks to maintain the correct shape of the main and to assist you in maining the correct headstay tension.

 

In a heavy sea upwind the runners and checks can also reduce the amount of rig pumping.

 

If your boat is set up with the runners and checks off center you will improve their performance by bringing them to center line.

 

Offwind remember to ease them enough that you can pull the rig forward and for long runs (unless your rig is really flexible) you can ignore them and seek to have the leward ones detached to avoid the chafe on the main.

 

Robin

 

Robin

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OK, in this crowd I am not the expert. I don't play one on TV and it has been a long time since I stayed at a Holiday Inn Express.

 

I think you are pretty much on it in the first graph.

 

How would you describe your mast: Thick & Stout or Thin & Spindly

 

Thick & Stout your runner and checks are pretty much for decoration and entertainment

Thin & Spindly, they are more important.

 

I would say ALL headstay control is the backstay. Loose backstay & tight runner could lead to inversion in the upper part. Very bad in deed.

 

Same goes for the checks. I don't think you would ever want them tighter than the runners.

 

I would normally start from the top down,

Tighten back stay for headstay sag

Tighten runner to adjust power in main

Tighten check to make the main even prettier

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My rig is pretty thin, it's definitely not the stout masthead rig. I'm amazed (and scared) at times at how much it bends. The fear is only because I've just never owned a boat with such a thin mast.

 

 

Checkstays vs. Runners - when I have the lines on the checkstay tackles let totally out, the runners and checkstays appear to tension at an equal pace. I'm assumming that since there's an adjustment on the checkstay that perhaps the designers intended for them to be tensioned more than the runners at times? Or it could be the previous owner didn't have long enough lines in the checkstay tackle...

 

Would there be an instance where you'd want less tension on the checkstays than the runners? Vice versa?

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Sucia,

 

Talk to your sailmaker is the best advise since the sail is cut to a shape that you want to maintain. If you get tension in the runners or the checks too tight, the sail won't fit the boat.

 

And make your changes before going to the tent at Oak Harbor, or having anything alcoholic to drink. Many Race Weeks ago the crew on Paddy Wagon "tuned" the runners and checks after spending time in the tent, only to invert the lower section of the mast the next morning!

 

JM

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Sucia,

Are your runners and checkstays completely separate? On most of the masthead rigs that I've seen that use both runners and checkstays, they merge and use one purchase to adjust them. The Checks and Runners adjust in tandem.

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Very important to sight the rig at the tuning stage. Boats such as the swan 56, with a relatively skinny masthead (aluminium as standard) rig, are very easy to invert if wound on indiscrimately by the Incredible Hulk (or any of the Marvel comic heroes, I guess).

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My rig is pretty thin, it's definitely not the stout masthead rig. I'm amazed (and scared) at times at how much it bends. The fear is only because I've just never owned a boat with such a thin mast.

 

 

Checkstays vs. Runners - when I have the lines on the checkstay tackles let totally out, the runners and checkstays appear to tension at an equal pace. I'm assumming that since there's an adjustment on the checkstay that perhaps the designers intended for them to be tensioned more than the runners at times? Or it could be the previous owner didn't have long enough lines in the checkstay tackle...

 

Would there be an instance where you'd want less tension on the checkstays than the runners? Vice versa?

 

Rule #1 - never assume the P.O. has everyting right unless the boat was a top program for the area. And even then you may want to question things.

 

Can you say "shrinkage" - There is a good chance the line chafed and was simply shortened.

 

Yes, you can want to let the checks off some. Perhaps you want to think of them as secondaries on a 4 BBL carb.

 

The amount of tension at any point will be adjusted for the amount of curvature you want in that area of the mast. You may want the bottom straighter than the top section(s)

 

Talk to Jibeset and see if you can get him to take a look at it.

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There function is to control depth and shape to your main along the luff. They can become tedious thats sailing,...fine tuning is what makes you that much faster..

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To answer the earlier question - the runners and checkstays are connected at a shackle, that is then connected to the control line and ran to a winch through a couple blocks. The checkstays have a small 6:1 or 8:1 block and tackle that attached to the main shackle so you can put more tension on the checkstay than is on the runner if desired.

 

 

As for the PO rule - I completely agree. That's why I'm checking in with everyone right now.

 

As for siting, I try to do this on a regular basis. I've got a decent amount of prebend in the rig, and I'm vary careful about pulling on the runners to avoid inversion.

 

I'm mainly trying to determine if there are trim guidelines for the backstay/runner/checkstay arrangement - something like the trim/shift gears cycle that's so common for other trimming. I think Lakeboy has come closest to what I'm looking for with:

 

I would normally start from the top down,

Tighten back stay for headstay sag

Tighten runner to adjust power in main

Tighten check to make the main even prettier

 

I just want to find is this the method the general rule?

 

Do runners like mine really effect the headstay sag much?

 

Any other advice on what to look for when using them?

 

 

I know this past weekend in 10-13 knots apparent with the 150% and a full main with moderate backstay tension, when we'd come out of tack and the runners were eased we'd see some backwind in the luff of the main up with the main sheeted in, top tell tale flowing 60% and boom slightly below mid-line. When we cranked in on the runner and straightened the rig, the backwind was reduce by about 90%. This seemed faster - but also seem counterintuitive since it should have made the sail fuller at the luff, and instead seemed to make it flatter - though I'm not sure if that was an illusion simply because it wasn't luffing. Does any of this make sense? Or did I start drinking too early?

 

There were times when the wind eased where I wanted more power, and I began to wonder if I should have eased the runner and backstay, but tensioned the checkstay to take some of the bend and prebend out of the mast and create more power in the main while creating more power in the genoa too.

 

The right idea? Or not?

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A masthead with runners sounds a little weird, but I think with the mast bent when you pull on the runners and checks you ARE tensioning your headstay. By taking bend out, you're pushing the masthead up (unless you're shoving the keel out the bottom -- your keel didn't fall off, did it?) which is going to bring on both the headstay and the backstay. That might be why your main bubble was going out -- genny draft going foward, genny leech opening up.

 

I'm basing this entirely on staring at the geometry, I haven't got one whit of experience with the setup.

 

If I'm right, you might want to go top down, and then back up. Backstay to take out some (but not enough) of the headstay sag, runners and checks until the main looks close, then a bit more backstay if the headstay's still sagging a bit much.

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Sucia,

 

Talk to your sailmaker is the best advise since the sail is cut to a shape that you want to maintain. If you get tension in the runners or the checks too tight, the sail won't fit the boat.

 

Best advice given, as the generalities are correct, but general. Control of mast bend, sail shape, and headstay control are the object of the game, but the sailmaker will give you the most accurate advice for your boat and sails.

 

Good luck to you.

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If your boat is set up with the runners and checks off center you will improve their performance by bringing them to center line.

Robin

It seems that the efficiency would improve but makes tack in rapid succession more difficult?

 

Sucia,

Are your runners and checkstays completely separate? On most of the masthead rigs that I've seen that use both runners and checkstays, they merge and use one purchase to adjust them. The Checks and Runners adjust in tandem.

On such a system I've always felt that tightening the runners loosened the checks; is that right?

 

There were times when the wind eased where I wanted more power, and I began to wonder if I should have eased the runner and backstay, but tensioned the checkstay to take some of the bend and prebend out of the mast and create more power in the main while creating more power in the genoa too.

Sounds very much like you know more than enough about runners & checks except I have no idea on that last paragraph. it seems like letting the runners & checks go and tensioning the backstay would be better???

 

A masthead with runners sounds a little weird

 

Why? (still learning)

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Well, it's just a more usual setup to use runners with a frac rig, as Sucia points out in the first post. The runners are more or less right behind the headstay attachment, so pulling runner on directly tensions the headstay.

 

On a fractional rig, the backstay bends the mast, but does NOT tension the headstay particularly (depending on where the headstay hooks on, it's either tensioned, eased, or nothing happens, as the masthead goes back and the center of the mast goes foward), so the runner is there to put tension back into the headstay, as I understand it. Everything's interdependent, of course, but roughly 'backstay for mast bend, runners for headstay tension. On a masthead rig the interactions are even more interdependent and seem less obvious. At least to me.

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To answer the earlier question - the runners and checkstays are connected at a shackle, that is then connected to the control line and ran to a winch through a couple blocks. The checkstays have a small 6:1 or 8:1 block and tackle that attached to the main shackle so you can put more tension on the checkstay than is on the runner if desired.

 

 

Runners and checks tied together so you always remember to let them both go. Easing the runner automatically eases the check. This is all good. I really don't think you ever want to see the runners sagging slack above a tight check.

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Checkstay tension should work in harmony with the runners. Stand by the shrouds and make sure that the checks don't invert the mast before the runners. Mark the tails of the runners where they enter the winch drum. Make the base settings Light, Medium and Heavy. Tape a batten to the backstay with corresponding marks. The whole idea is to have easy to achieve base settings that will get you up to speed quickly so you can keep your head out of the boat and sail. HTH V92

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Henry McCray did something similar to the SR 33 Temptress...She won KW in her div...Might be on to something here

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Does the SR33 have a Masthead rig with checks & runners? Any others that folks can think of?

 

Or Vegas were you just talking about the measurement/marking system?

 

To that end, I have navy blue runner lines - is the best way to mark these line with a whip of contrasting line? Or do you know of markers that will mark dark line? Perhaps those funky silver/gold ones?

 

 

I appreciate the sail maker advice, and I hope to do that - but I'd like to get as much sorted out as I can so I can use their time in the best possible manner.

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I have used different colored Magic Markers and the PVC tape to match on the backstay batten. Think green,yellow and red or whatever makes sense to you.

Whipping reference marks on the tails would work as well. Just a bit more labor intensive. And yes this system was used on an

masthead IOR 50 back in the day.

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Any other advice on what to look for when using them?

I know this past weekend in 10-13 knots apparent with the 150% and a full main with moderate backstay tension, when we'd come out of tack and the runners were eased we'd see some backwind in the luff of the main up with the main sheeted in, top tell tale flowing 60% and boom slightly below mid-line. When we cranked in on the runner and straightened the rig, the backwind was reduce by about 90%. This seemed faster - but also seem counterintuitive since it should have made the sail fuller at the luff, and instead seemed to make it flatter

You probably increased the twist(eased the leech) as you brought on the runners, this would reduce backwind bubble a little. we sail with a little bubble but racing w/ one of my betters recently they trim the gennie out for no bubble and depend on boat sped to build lift and they use their trim tab to go to windward while keeping the nose down. that is an option we don't all have. Is it possible that your jib trimmers matched the slot while you were fooling w/ the runner? Wouldn't that be a good problem: too efficient trimmers!

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Does the SR33 have a Masthead rig with checks & runners? Any others that folks can think of?
SR33 is fractional. Many 80's IOR boats with spindly masthead rigs had runners and checks, attached on centerline to avoid any lateral distortion in the mast column as you pull on the runners/checks.

 

To that end, I have navy blue runner lines - is the best way to mark these line with a whip of contrasting line? Or do you know of markers that will mark dark line? Perhaps those funky silver/gold ones?
I have used thin bands of white whipping twine on dark control lines at key measurement points. They can then be colored with markers if need be.

 

Robins post at the beginning of this topic is right on + the other post that referred to using the runner to remove compression and forestay sag brought on by max backstay. You might want to ask a Star sailor at CYC in Seattle to take you out. I know it's not a masthead rig, but in half an hour, you will get an immediate tutorial on their relative affects on trim and speed. e.g. To indicate how essential it is to control on a spindley rig, you don't play the mainsheet alot upwind on a Star. The sheet is typically pulled on and cleated for a given wind speed range. After that, all the main trim and forestay sag is achieved with runner and checks. The checkstay's role is primarily to quickly power up or flatten, but it's done in conjunction with the runner tension. It would be a good exercise to borrow concepts from that boat.

 

The runner on the masthead rig is performing a dual role of assisting the backstay in pulling back, reducing some compression, and adjusting forestay, while also handling draft depth up top. The checkstay has a bigger impact on draft depth in the main lower down (accounting for why it has an independent set of blocks to fine tune draft depth), but it too plays a role in reducing some compression.

 

You definitely want to avoid piling on more checkstay than runner. One of the easiest way to get a new rig.

You seem to be doing all the right things in finding out, but your best bet is a sailmaker that was around when checks and runners were used on masthead rigs.

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Runners are also needed if the spreaders are not swept back (something like 20 degrees) on a mast head...

With swept spreaders, I think only checks are possibly needed.

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Runners are also needed if the spreaders are not swept back (something like 20 degrees) on a mast head...

With swept spreaders, I think only checks are possibly needed.

 

That's my situation on our S2 10.3. Just runners, no checks, straight (not swept) spreaders. I think you are implying that the runners are there primarily to ensure that the rig stays in place (because of the lack of backwards pull from the shrouds) and secondarily for tuning depth of main draft. Yes? No?

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WunHung:

Thanks. Quick follow on question though, what I am I looking for when it comes to pulling on too much checkstay. I'm assuming this would be inversion of the lower part of the rig making something of an 'S', right?

 

I'm assuming that I want to use the checkstay to help return the rig to the shape similar to non-loaded rig to match the built in luff curve of the main. So I'd want to pull on enough checkstay to just straighten the bottom portion of the rig to it's prebend.

 

I like the idea of sailing on a Star. I'll have to try to do that sometime later in the season.

 

Sockeye:

I've been playing with that recently. My boat points very well, but I'm afraid it's slow when that's happening. So I've been working at keeping the nose down and staying fast then working up. Been working with both of my trimmers to get this habit down - but the boat is relatively new to us so it's taking some time to find the key numbers in the different wind conditions.

 

I'm looking forward to the regatta weekends. It'll be the first time with my boat, and should be a great opportunity to do some close up speed testing to figure out what works. We'll probably get the crap kicked out of us, but we'll learn.

 

DannyV:

I would love to buy a boat with swept spreaders, but alas my pocket book may not be as endless as yours. If money wasn't as much of a consideration as it is, I'd probably be floating around in a J109 but I've got a wife, a mortgage, etc. Glad to hear that you have those kind of options though.

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Sucia:

I have a bendy double spreader masthead rig with single checkstays. It seems to me more like you actually have upper and lower checkstays. I don't see how you can call the upper check a running backstay (runner) as you have a masthead rig and what you are calling the runner does not lead to the top of the mast where a backstay would lead. I say set the tackle on the lower checks either harder, softer or evenly tensioned with the upper checks as is needed for smooth mast bend control and consider them to be one.

 

My $0.02

 

mfbr

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Sucia,

When you set up the checkstays you are trying to keep the mast shape somewhat constant, too much and you will invert the lower section like I mentioned when I was refering to Paddy Wagon years ago. But just as important is what you are trying to do to the main as you load up the checkstays. This is what you need the sailmaker for. They can tell you what shape you should be trying to get as the wind increases as well as preserving the mast shape to keep it in the boat.

 

JM

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WunHung:

Thanks. Quick follow on question though, what I am I looking for when it comes to pulling on too much checkstay. I'm assuming this would be inversion of the lower part of the rig making something of an 'S', right?

Next time you're out sailing upwind pre-race (8 to 10 knots would be a good windspeed to play with), start out with whatever backstay makes you happy for forestay sag, snug the runner to help the backstay with maintaining the right sag, and have a slack checkstay. Watch the mainsail luff, draft depth and leach as you gradually increase the amount of checkstay.... it will get very ugly well before you get to the point of inversion You'll probably see an increasing bubble in the main. watch your boat speed as you gradually do this and see if you start to get a bit more weather helm. Try not to get more than 3 degrees of weather helm....and don't make the changes so fast that the boat hasn't had time to respond to the change.

 

I'm assuming that I want to use the checkstay to help return the rig to the shape similar to non-loaded rig to match the built in luff curve of the main. So I'd want to pull on enough checkstay to just straighten the bottom portion of the rig to it's prebend.
You could look at that way as mental reference point. In relatively flat water and perhaps 8 knots, on your C&C, I would think that most of the mast control, forestay sag and mainsail shape can be achieved with backstay, vang and mainsheet, and the runners and checks are just snug to control any minor pumping, As you say, in this condition, you might use the unloaded mast's prebend as a baseline. Then try the exercises above in tweaking the checks..

 

Have you got a side view of your mast you can post showing your baseline prebend? Does your C&C have a babystay on a small track? At the time C&C still tended to favor babystays for additional mast and prebend control along with the diagonals. With all tension off the backstay, runners and checks, how much rake do you have in your mast?

 

I like the idea of sailing on a Star. I'll have to try to do that sometime later in the season.
You'll get instant feedback on mainsail shape and forestay sag...great learning platform...fractions of an inch make a difference...tough boat to get it all 100% right.. but after a Star, most other boats with runners are a doddle. :P

 

Once you have the hang of using the runners and checks, you'll enjoy the extra bit of control when the wind is up in the teens. I hope you have a really keen maintrimmer to stick with it to get it right (and/or another pair of eyes to help watch the shape and numbers)

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Runners/checks also really handy to help power the boat out of a tack in light/medium air. Leave the backstay where it is, and as you tack, pull on a tiny bit more runner than you normally would to straighten the mast, and deepen the main. Trav is a few inches further up, and pop a bit of mainsheet. As the speed comes up after the tack, down the trav, sheet on and ease runner, all at the same time. Makes a big difference with bigger heavier boats with smaller mains, as the main is the principal accelerator post-tack, and you need to give it all the help you can.

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