Stay Tension

[The Garbone]

Our boat was unsailable when purchased with rotten spreaders, loose shrouds etc. We replaced the standing rigging and spreaders. Taking the mast down and using the old rigging for measurement of the new.

Installing the new rigging when we put the mast back on I have tuned it myself.

My problem is I can only get 750lbs of the 1400lbs of tension on the fore/ backstay. All the other shrouds to speck but I have no more turns left on either end. I can't imagine this being catastrophic but it is a concern on my part.

Any suggestions? I would hate to have to cut 2" off the forestay (staylock under the furler).


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[chris95040]

Originally Posted by The Garbone

Our boat was unsailable when purchased with rotten spreaders, loose shrouds etc. We replaced the standing rigging and spreaders. Taking the mast down and using the old rigging for measurement of the new.

Installing the new rigging when we put the mast back on I have tuned it myself.

My problem is I can only get 750lbs of the 1400lbs of tension on the fore/ backstay. All the other shrouds to speck but I have no more turns left on either end. I can't imagine this being catastrophic but it is a concern on my part.

Any suggestions? I would hate to have to cut 2" off the forestay (staylock under the furler).


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How is your rake? That'll tell you whether its your forestay or your backstay that you'd want to shorten.

I agree it doesn't sound dangerous in its current state, but those new stays will probably further loosen a bit. And if you're supposed to be at 1400, I guess you should probably try to get there.

Is there any other backstay/forestay hardware (at the top, or at the base) that you could shorten (a toggle or a fork or something that could be replaced with one that has a shorter pin-to-pin distance, for example?)

Perhaps give some more details. If its a deck supported mast, make sure the deck is sound underneath, the mast step, any compression posts, etc are all sound and doing their job. Any failure there could cause the mast to droop into the boat and result in looser standing rigging.

[Stumble]

Something is seriously wrong with your process. Forestay length is set based on the cut of the sail NOT tension. I have no idea what that length should be on a Catalina 30 but the numbers shouldbe out there. Try contacting the sail maker who built the sail and ask what forestay length it was designed to. This is the pin to pin forstay measurement, and should be measured with a tape measure.

On a race boat you may adjust off of this neutral a little bit (2-3 turns of the turnbuckle) for light vs heavy air, but cruisers just pin it in place.

Forstay tension is adjusted by the backstay preassure, not by adjusting the forestay length. Otherwise you get a jib that bags up on the sta and can't be trimmed correctly.

[unclemack]

First I'd check lengths of the stays are as specified. Don't know if this is your model - wish there was a manual for my boat though...

http://www.catalina30.com/techlib/Pa...al/Rigging.pdf

edit: just noticed the split backstay adjuster in the pdf. Not yours I take it?

[The Garbone]

So working on the assumption that the forestay/tang is the correct length of 41'6.5" per the manual I need to look at my backstay (yes, I am doing all the adjusting there).

I currently have what looks like a longer triangle plate (split backstay) that I may be able to install a more symmetrical one that is an inch shorter. Maybe that will give me my 700lbs more tension.

I think I will measure the forestay from pin to pin next time up the mast. ( I have to replace my vaporized vhf whip eventually).

The mast has a slight rake as per the hanging the wrench on the halyard test. 1" or 2".

That is the thing about being lacking experience and having an old boat I guess. There is no record of what had been screwed up over the years and what to check.

[unclemack]

Shouldn't the split backstay adjuster assembly - the block & tackle that pulls the two parts closer together - provide plenty of tension control?

Drawing is on page 23 of the .pdf I linked.

Surely enough to straighten the forestay when needed?

Maybe it's in a locker somewhere?

[jeepbluetj]

Originally Posted by chris95040

...

Perhaps give some more details. If its a deck supported mast, make sure the deck is sound underneath, the mast step, any compression posts, etc are all sound and doing their job. Any failure there could cause the mast to droop into the boat and result in looser standing rigging.

Catalina 30's are deck stepped.

They are also quite renown for having the block under the compression post rot out. Look at the deck around the mast for stress cracks - there is a possibility that full tension will drive the mast/deck/compression post down.

[The Garbone]

The compression block is fine, as are my other shroud tensions. I imagine everything would be out of kilter if the mast was rotting down thru the deck. One of the reasons we bought the boat was the bulkheads and compression post and block in the bilge look to be excellent condition.

My understanding is that the backstay adjuster is for rig tuning for conditions not initial setup.


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[chris95040]

Originally Posted by Stumble

Something is seriously wrong with your process. Forestay length is set based on the cut of the sail NOT tension. I have no idea what that length should be on a Catalina 30 but the numbers shouldbe out there. Try contacting the sail maker who built the sail and ask what forestay length it was designed to. This is the pin to pin forstay measurement, and should be measured with a tape measure.

On a race boat you may adjust off of this neutral a little bit (2-3 turns of the turnbuckle) for light vs heavy air, but cruisers just pin it in place.

Forstay tension is adjusted by the backstay preassure, not by adjusting the forestay length. Otherwise you get a jib that bags up on the sta and can't be trimmed correctly.

Their forestay is new, as is all their standing rigging. Presumably something is a bit longer than what was there before. Or the previous owner kept it at a lower tension than the OP wants.

I think the assumption that a forestay length in a book is going to match up precisely with what he's got now assumes an awful lot of other influencing pieces haven't been modified over the years. Couldn't one influence their forestay assembly, and therefore the "pin to pin length", pretty significantly without actually needing to make any modification to the sails (chainplates, masthead assy, tangs, etc.) ???

As long as the tack + head end up where they want to be, and theres enough room for the luff of the sail, the exact geometry of where a stay ends and a tang begins doesn't matter much.

Someone may have had reason to dork with that, and this is why its important to do as you say: Measure it! But that implies a rig thats already up and set with the appropriate rake, which I believe the OP did not have.

OP - I'd do what you are doing, namely, whatever it takes now to get the tension where you want it while having the mast in column with the appropriate rake.

[barnakiel]

Originally Posted by The Garbone

My problem is I can only get 750lbs of the 1400lbs of tension on the fore/ backstay.

IMHO fore and back stays have different tensions. The fore stay always seems under more tension, which seems about right given the angles the stays make with the mast (on most boats).

Selden pdf gives tensions as percentages of the wire`s BL. Perhaps this is some indication of how much is 'good' in your case too.

b.

[unclemack]

With a foil on the forestay not sure how you're measuring tension there?
Tension on one side of the split backstay will be half that at the singled upper section.
But I expect I misunderstand your posts in some way.

[chris95040]

Originally Posted by unclemack

With a foil on the forestay not sure how you're measuring tension there?
Tension on one side of the split backstay will be half that at the singled upper section.
But I expect I misunderstand your posts in some way.

Great point!!

Of course theres some trigonometry to really find out exactly how the tension in the lower segments affect the tension in the upper segment, but unless you're lower segments are practically horizontal Unclemack's rule of thumb should get you in the ballpark.

[UNCIVILIZED]

Regarding measuring your headstay's length, you can't do it with any accuracy, when it's in place, particularly with a furler overtop of it. Because the catenary (curve) induced by the foil & sail, will alter the measurement by a good bit. Assuming that you're looking to measure within tolerances of less than an inch or two.

Also, the figure given by Catalina, is a nominal one. Different makes & lengths of tangs get used at different times, people alter the rake of their spars. Including by having the butt shaved for rake, etc. Or even have spars shortened slightly, to trim off a corroded or cracked base. This even occasionally happens before the boat leaves the production facility…

And the length of stays, & other elements of rig tune, get changed all of the time. Notoriously by racers, but by lots of other folks too. Up to, & including the length of, yes, the headstay. By a Lot more than just a few turns on the turnbuckle.
A good number of racing boats, do it by several inches (or closer to a foot) or more. Even/especially when under sail.

The actual headstay length on a cruising boat, though, isn’t super critical. But if you want to get an accurate measurement of it's length. Take off the jib, unpin the stay, & lower it & the furler, together, down to the dock. Then put it under a bit of tension, & you can get a real world, accurate number.

I'm saying that knowing the exact length isn't critical, because unless your furler & jib are right up next to the halyard's sheave box, then odds are you could bob a few inches off of the wire, without it affecting much.
But since you're going up the rig, take a tape measure & a camera with you. It'll help you to verify things, position wise. Especially that your furler’s installed correctly, & whether or not you’ve got room to shorten it. Plus the camera will let you look at your masthead, stay, furler, & halyard setup later on. That & also to have other folks assist you in diagnosing things. Including the above (possible) length/interference fit quandary.

Should you decide to shorten it by a bit. Then, post headstay bobbing, after tuning everything else, & having taken her out for a few test sails; if you're helm is squirrely, & you track it down to needing more headstay length. Then you can always add a toggle or two, or a set of link plates.


As an example of headstay length tolerances:
On my 1st boat, a Ranger 33. I needed to do some work on the furler’s lower end. Which necessitated me lowering it & the headstay onto the dock. And in the process of doing the work, I had to take 3”-4” off of the stay, & then later reinstall the Stalok.
When I put the stay & furler up, there was zero noticeable difference in anything.

Odds are it’ll be the same on your boat. As on most boats, except racers, the sails & furlers, are cut/setup with loose enough tolerances to accommodate sails from various makers (including warehouses half way around the world). And on boats which vary dimensionally, from one lot to the next. For no two of them are exactly alike.

Sails are cut to fit boats, not the other way around. Which is why sailmaker’s traditionally come down to a boat & measure her, prior to making her a new sail.
And sailmakers modify sails all of the time. Such makes up a good percentage of their business.
Plus, & cropping 3”, or even 6” from the head of a jib, takes less time than does rolling it up, & putting it into it’s bag for transport. And is exceedingly common to boot.


Disclaimer: DON'T believe anything I say. Go out & read/research things yourself. Then try'em out. Take stuff apart, & don't fret if you break gear. You'll learn to fix it. Sail... A lot.
And: Get to know marine professionals, as friends.

[The Garbone]

Originally Posted by unclemack

With a foil on the forestay not sure how you're measuring tension there?
Tension on one side of the split backstay will be half that at the singled upper section.
But I expect I misunderstand your posts in some way.

The backstay turnbuckle is above the triangle plate/ split. I can reach up with the loos meter and check the tension on the 1/4' wire about a foot above if I stretch.

I am working under the assumption the forestay is not really adjustable and its tension will be some percentage of the backstay and not overly critical as the the backstay is the one that resists the forces of the sails and affects the rake.

My concern that of the forestay being too long may not be the correct solution. I am more apt at this point to shorten both sides of the backstay bridle an inch than monkey with the Stalok on the forestay.

Is 700lbs vs 1400 on the backstay worth the time and effort? Or can this be put in the good enough file?

[unclemack]

Some furling units do have adjustment for stay length.
Both my Selden Furlex & my SCRR do for example - no clue about yours.

If I wasn't sure whether my forestay had adjustment I'd check - even if only so I could be certain that any adjuster wasn't near the ends of its threads and that it was locked securely.

You may have done this but it's not clear from your posts, sorry.

Good luck, hope you resolve it.