Standing Rigging Tension

[Jim Payton]

A buddy was out in San Diego Bay just sailing around to relax single handing in his 22 foot Columbia, when his port side mid mast stay broke. He was able to stablize the mast with some extra rope he had aboard and get back to the dock, but he told me afterwards that it was a very tense moment and he couldn't remember moving that fast in a long time.
We talked about what the possible causes were for the failure of the cable (it actually turned out to be a defective turnbuckle). We thought, and with the input of some local dockside neighbors we decided that a major contributing factor was that the tension on the cables was entirely too loose.
I've seen one of my neighbors using some kind of tension gage to check the tension on his rigging. I was wondering if there are specs on what the tension should be on the standing rigging? Are these gages worth using? It seems to me that the tension would change as weather changes. I have noticed that some times while my E-26 is setting in the slip that especially the mid-mast stays are loose and at other times they seem to be ok.

 

[Ray Rhode]

There are many opinions on rigging tension. The problems you can get into are two. Too loose and the shock loading when you tack will impose greater streeses on the rig. Too tight and the rig is always under a greater load than is required. This includes the mast compression post if the mast is deck stepped. I set my rig so that the mast stays is column and the leeward shrouds still have tension on them in a pretty stiff blow. The gauge you mentioned is probably a Loos gauge. I believe it comes with some general info on the load limits for various size wire and recommendations for initial tension. I use one and find that it is very helpful in verifying that the rig tension is balanced port and starboard.


Ray Rhode
S/Y Journey

 

[Loren Beach]

Most Columbia 22 were built in the 60's, or maybe the early 70's. I have seen many boats from this era with original rigging and turnbuckles. Big Big risk, imho.
The riggers I have talked to over the years all seem to advocate replacing standing riggning on a regular basis. In round numbers, and in cooler climates, 10 to 15 years per cycle. Half that time in warm climates, expecially in salt water.
Your friend may have been depending on ancient fittings and wire waaaay beyond its duty cycle, and prayer, to keep that rig up.

I realize that spending any (!) money on an older boat risks putting more into it than it's market value, and this causes a lot of owners to take risks that could result in injury.


Taking a great (unwarrented?) leap to a conclusion -- he should re-rig. The cost will amortize out in a season of stressless recreation on the water.


I do admit to being an advocate of preventative maintenance. I have crewed on too many boats where equipment and rig failures have ruined vacations.

Best,
Loren

 

[u079721]

First, I agree with the above that your friend should re-rig. If one part went, the rest may follow.

As for setting the tension. I am a very anal analytical-analytical type of guy, and I couldn't make it without my Loos Tension Guage. I also highly recommend Brion Toss's video on rig tuning. In it you learn that the standing rigging is meant to be tensioned to a certain percentage of its breaking strength, which is a function of its diameter. So all you need is a caliper or gauge to get the rigging diameter, and a Loos guage to help set it.

 

[Geoff Johnson]

Actually, the Loos gauge (at least the "professional" model) has wire diameter gauge built into it. After viewing the Toss video I started to tension my rig at 20% UBS for the upper shrouds, 15% percent for the intermediate and about 10% for the aft lower and 12% for the forward lower shrouds.

 

[ted_reshetiloff]

This question is more for Steve C. as he had an 89 E 38-200, but others may know as well. What were the tension numbers you were using from the Loos gage? I'm pretty happy with my rig tune thus far, mast stays in column when heeled etc. I do seem to have a bit more headstay sag than I would like and I think I have the forestay pretty tight and the backstay as well. I also know that given the slight sweep of the spreaders the uppers and intermediates tension can impact headstay sag. Would love to get some numbers to start with. I'm borrowing a Loos gage this weekend. I have one for the dinghy my wife and I race but the wire size is too big for it...

 

[gareth harris]

I can not open the documents on this web site for the E26 using a library computer, is there anything useful to you in the standing rigging specifications?

For the E35-2, the owner's manual states that the leeward shrouds should still have tension under sail in 10 kts. That works out to be about 1200 lbs. For the E26 it will be considerably less.

Gareth
Freyja E35 #241 1972

 

[u079721]

E-38 Rig tension

Ted,

I am a devotee of Brion Toss, so I do whatever he says. And for tension, that means 15-20% for headstay, backstay and uppers, 10-12% for intermediates, and at least 10% for lowers.

On the 38 I was a bit of a wuss, and tended towards the lower end of the ranges, but I don't recommend that for best sailing, and in fact I did tend to have too much sag in my forestay, and if really hard on the wind would sometimes have the lowers go a bit slack. (But I was never racing.)

For the backstay and uppers a minimum of 1500, and 2000 would be better. For the intermediate that would be at least 650, and for the lowers, I usually set them to 10% (800) but that still tended to sag. So I would probably suggest 1000 or even 1200.

I used the Loos 90B gauge, and it really isn't up to the task, as the difference between 15 and 20% on the larger wire (9/32") is just about at the extreme end of the range of the instrument. But it's a great place to start.

 

[Seth]

rigatoni

All excellent comments-The problems with too loose of a setting are the shock loads as previously mentioned, and the fatigue that will result from the constant movement of rigging without sufficient tension.

Unless you go to an extreme, the primary concern with a tight rig is deck compression-beyond that the woest thing that is likely to happen is a loss of performance in light air. Again this assumes you don't crazy with the tension.

For a boat like yours, start at the dock using the main halyard shackle as a guide and set the rig straight in the boat side to side. You can tell (with reasonable accuracy) by pulling the halyard tight to a location on the deck that is identically located on both sides-usually a chainplate is good for this, or the forward end of the outboard track. Pull the shackle down to the top of the chainplate and go back and forth from each side until the top of the rig is in the center of the boat. Set the lowers with about 80% of this tension, sighting up the rig to be sure you are not pulling it to on side or the other. Set the headstay and backstay with roughly the same loads as the uppers, and start with 2-3" of aft rake.

Before all of the engineers come unglued, this is the down and dirty way to get in the ballpark-obviously you can do better using a tape measure instead of the halyard, and Loos guages instead of "feel". OK?

Go sailing, using the biggest headsail you can fly in the conditions without being too overpowered. Sail UPWIND, sheeted in hard and sail SLIGHTLY low, so that the sails and rig are FULLY loaded. This is important because if the rig is not loaded up you don't have a good reference point. Sighting up the windward side of the rig, tweak until it is in column on both sides(if you need to make an adjustment, just tack so that the side needing a tweak is loose, then tack back to check.

When you are done, the lee rigging should be just barely unloaded-NOT swinging around and loose, but not snug either (the newer boats should have tighter lee shrouds-this is for YOUR boat).

If you feel you have too much weather helm (more than about 7-10 degrees of rudder angle to hold your upwind course-or by feel), then remove aft rake by easing the backstay and taking up the same amount on the headstay-so that when you are sailing upwind and sheeted hard, the boat will SLOWLY turn head to wind when you let go of the wheel or tiller. If it rounds right up you may have too much aft rake. If when you let go the oat begins t bear away, do the reverse and add some aft rake.

Again, this is appropriate for a small cruiser, who just wants the rig to be close to optimum tune, and more importantly, safe without giving up too much performance.

Good luck, and my apologies to the engineer types!

S

 

[ted_reshetiloff]

All great posts and I thank you all for them. I did both methods basically. I first got the rig straight in the boat using the main halyarrd. Then set the rake. Then worked down to the lowers. Then I used the tension gage to get to about 2k on the uppers, 950 on the intermediates, and I think 800 or 900 on the lowers. Sailed the boat in 25-30kts saturday. Lee shrouds we slightly unloaded, not swinging. Boat was very balanced. Headstay sag was too much though. I have all new shrouds and I fear they may have to shorten the forestay. It is almost bottomed out and I have plenty of backstay on. I dont want to put too much more backstay on as it induces too much prebend for the main I have. (flattens the main too much) I suppose I could install some running backs and maybe check stays but I don't think my wife will let me pimp out the ride too much...She is a bit edgy on my wanting to apply for a phrf rating even though I promised not to buy any racing sails... Taking out the guys from the rigging shop friday evening for a sail to see what they think about the headstay sag. I guess its probabaly not too bad, I just come from a racing background and hate to see poor sailshape. I really need a hydraulic backstay but its not quite in the budget yet, still need the feathering prop...

 

[Seth]

more pasta

Ted,

Obviously my comments were geared towards the Columbia 22 or similar boat.

You are exactly on the right track for your boat, and the only thing I may be able to add is this:

Play with the aft lowers-get them as tight as you can without inducing reverse bend. They will restrict the bend caused by the backstay and allow you to carry more backstay with less mast bend.

Having said that, in my view it is hard to get most mainsails too flat-especially on a boat like yours. Most are way too full. Think about it this way:
The times you are seeing excessive headstay sag is when the breeze is up. Remember that in lighter air you want as much sag as you can get (unless it is flapping in the breeze, of course!). By the time you have 10 knots TWS, the boat is well heeled and certainly by the time you are in anything over 10 knots the mainsail should be BOARD FLAT. These are somewhat tippy boats, and I can tell you that if I were sailing upwind in 10-12 knots true with the #1 (and this is the very top end of #1 for these boats-assuming a 150-155% sail), if the main is not boarded out you will have a lot of backwinding, too much heel, and generally be slower than if you had the sail nice and flat. Even if I were using a 135% genoa, in anything over 10-12 the boat should do a lot better with a flat main.

I think if you tweak the aft lowers just a bit to restrict bend (if you are sure this is an issue) just a little, and then get used to seeing a very flat main when the breeze is up over 10-12, you will be in good shape.

Remember too, that running backs also restrict mast bend, so that you can carry a lot of rig load (backstay) without overbending/overflattening the main. Same issue, though: be carfeul about having too full of a mainsail-it is NOT fast. Babystays, on the other hand INDUCE mast bend (and reduce pumpng in a seaway-runners also help in this), which would allow you to have a flat main with less sag. I would do away with the babystay for buoy racing though-it is a pain to tack around.

Bottom line: Flat mains are FAST once the boat is moving at or near hull speed. Headsay sag is FAST in lighter air.

Sorry if this is too basic or is redundant.

Sail to win!

S

 

[ted_reshetiloff]

I agree 100 %. The lowers definately need some more tweaking. Really wish I had the hydraulic backstay though. I feel like once I get the forestay sag where I like it it will be to tight for the light stuff. I also am thinking my forestay may be too long though. I need to check the rake again. I was using a bunch of heavy wrenches on the end of the main halyard to measure the rake. Been to windy to recheck. I thought I read somewhere that I should see 3-4 inches. Question is is that a good number for an E 38? My thought is that 3-4 inches would be a lot for 25 footer and maybe not much for a 40 footer. Other problem is that the loos gage I borrowed was not big enough to do the backstay which is 5/16. I was also almost off the chart for the 9/32 uppers. Scale barely went to 2000 for those. As I am very new to this boat and have all new shrouds which will stretch I am guessing I will be tweaking the rig for some time. I am also having problems with my knot meter as I dont think I should have painted it with antifouling. It was working before I painted it. The connections near the sender are a little suspect as well due to corosion. I am hoping I can get the boat to hit its polars but right now my instrumentation is not 100% up to snuff. My wind meter is ging me the blues too. The adjustment screw on the back to get the apparent angle set is trashed. The screw was plastic and is all chewed up. Also DMI rebuilt the masthead unit but it seems to read low on windspeed. Just looking at the unit the cups appear to be spinning a lot slower than the ones on the boat next to me who's mast is the same height. Not sure if its worth trying to have the bulkhead unit worked on or just save my pennies for a whole new unit.

 

[Geoff Nelson]

Tuning a cruiser

Wow! Great thread. I bought my E-381 to cruise and to prove to myself I can sail and not race (I race my 5o5 and do main on a J120 and will race anything else someone will put under me- that's when I'm not teaching racing at JWorld!).

Since then, I have renewed the PHRF rating (117 Sweeet!), bought a new(used) spinnaker and entered the Newport-Ensenada race with a crew of 8. Already have 9 people bugging me to get a Wed night Beer Can program together this summer. Guess I really have an addiction! Oh well. Anyway, my point is thanks for the info and I plan to work on the rig tuning on the way to Newport from SD on Wed/Thurs. Unfortunately all the turnbuckeles are forzen and green from lack of lube/care. Does anyone have a good recipe for breaking them free? I am nervous yarding on them the day before the race for fear of breaking something so close to the start but I want it to be better than it is. I just know it is way off and have not even messed with it. Fortunately, it is a mostly downhill race so if I don't adjust, it shouldn't kill us.

btw- I love the Navtec hydro backstay- I also have a lot (in my mind) of headstay sag (~18-24" in 12kts with the back stay way on) but it still cleans it way up when changing gears quickly.

Has anyone put together an adjustable jib fairlead system (aside from the std car)?

Thanks,

Geoff

 

[Geoff Johnson]

I have just installed the Garhauer adjustable cars. The only one available (AFAIK) that has ball bearings and works on the Schaeffer (and Merriman) T-track. You can see a picture here:

http://clients.sailnet.com/c470/html/body_adj__lead_cars.html

 

[Seth]

loads on rig

Ditto the Garhauer gear-the easiest solution short of going to Harken track and cars. Try liberally applying penetrating oil to the turnbuckles-leave it overnight. If that doesn't work, try using heat-

Regarding loads and tension, unless you plan on adjusting the shrouds for different conditions(which makes a big difference in performance-most serious racers do this now before or between races), the exact tension does not matter really. If you follow the proper tuning procedure in the right conditions (10-12 knots breeze, biggest genoa, upwind, fully loaded up by sailing slightly fat) you will end up with the right tension for your purposes.

As for rake on the 38-if the boat were in race trim (meaning STRIPPED) I would start with 3-5" of aft rake. Slightly more if you sail in very light air, slightly less on SF Bay. BUT, since many boats have cruising gear with weight distributed differently, this may need to be tweaked for your boat. If you have lots of weight aft this will tend to reduce weather helm and you might try more aft rake (if you feel there is little or no helm at all). If you have lots of weight forward (which induces weather helm), try a bit more fwd. rake. Experiment until you can get the boat to slowly turn into the wind when you let go of the wheel while sailing hard upwind in anything over about 5 knots of breeze. If when you let go of the wheel it spins right up, move the rake forward. If the boat bears off when you let go, rake it a bit more aft.

Headstay sag: For a cruiser, it is OK to see 8-10" when loaded up (as above). If you consistently see more than 12" you need to reduce the sag by more haestday tension, backstay tension, or both.

Racers would like to see 4-8" in light air upwind, and try to keep it under 6" when the breeze is up.

Good sailing!
S

 

[Geoff Nelson]

mast rake

I know I am getting a little off the topic of shrouds but I am foggy on the rake comment Seth.

"I would start with 3-5" of aft rake. Slightly more if you sail in very light air, slightly less on SF Bay."

My natural inclination is to rake more in heavier air, flattening the jib entry and belly of the main while twisting off the top of the main to depower. It's how I trim the main on the J120 I race on and we are fast. What am I missing?

Am I applying dinghy tuning in the wrong way or are you using this as a start point so you have more room for adjustment as the wind picks up?

As for the shrouds, I know that they are all off as I replaced the backstay and they all got tweaked when that process happened and they were never put back into alignment.

Thanks,

G-

 

[Seth]

This could take a while...

No problem Geoff-this is a very common area of confusion, so let's clarify:

You may be confusing rake with BEND.

Rake is used to balance the center of effort (combined CE of main and headsail) with the Center of Gravity (in the keel). It has nothing to do with sail shape, since you could have the top of the mast in any fore and aft location, yet keep the same tension on the headstay and backstay, right?
For example if you wanted more forward rake you ease off on the backstay 3 turns and take up on the headstay 3 turns. You have kept the load the same as before, but moved the whole rig (and CE) forward).

This is rake as opposed to bend, and it works like this: with all other things being equal, if you move the CE forward of the CG (think for this discussion of the CG as a pivot point on a windvane), you will have the driving force of the sailplan FORWARD of the pivot point, which would "blow" the bow AWAY from the wind. This is felt as "lee helm", or the tendency of the boat to bear away when you let go of the wheel/tiller.

If you rake the mast AFT of the "pivot point", the driving force is now BEHIND it, and the STERN will be pushed AWAY from the wind (and the bow into the wind). This is experienced as "weather helm" or the tendency of the boat to head up into the wind when the wheel/tiller is let go. A small amount of weather helm is usually desireable for optimum upwind speed and pointing-as the boat will have a natural tendency to sail higher-which helps you point higher-and you can find a "groove" where the boat has that magic combination of speed and pointing. If you have a perfectly neutral helm (meaning the CG and CE are perfectly aligned), you will always be trying to force the boat higher, rather than finding a groove. You will have good speed, but not optimal VMG upwind. However, this neutral helm is very fast for reaching and running. We don't adjust rake to a large degree while racing (with some exceptions)for sail shape, but we DO change BEND. There are times that we DO adjust rake, but it is for balance-not sail shape.

The kicker to this picture is the CG (pivot point, CE of the keel, etc.) can be affected by moving weight around the boat. If the boat is at rest, empty, this point is somewhere in the middle of the keel. But when you are sailing, this point becomes the combination of the keel AND crew/gear weight.

If you move the weight way aft, the effective CG becomes a combination of the keel CG and the center of the weight on the boat (you and your crew, + gear), and the actual CG is now somewhere BEHIND the keel. If the mast were aligned perfectly with the original keel CG, you would now have the rig CE FORWARD of the boat's CG-creating LEE HELM. Move most of the weight forward and the reverse happens: WEATHER HELM. Have you noticed in photos of heavy air sailing the crew weight is in the back part of the boat, while in light air pictures the (good) boats have the weight forward-especially upwind? This is largely because in light air upwind, you are working to give the boat a bit more WEATHER HELM to help it point higher, and in heavy air, when there is naturally more WEATHER HELM, the goal is to reduce the WEATHER HELM and the excessive rudder drag that goes with it.

Weight forward= weather helm; Weight aft= lee helm
Rig rake forward= lee helm; Rig rake aft= weather helm

For rake tuning, just sail the boat in it's usual trim and adjust the rake until you have just bit of weather helm in anything over 4-5 knots of breeze-no more than 1/4 turn of the wheel. For rake adjustment, read on.

Now comes BEND. The purpose of mast bend (on masthead rigged boats) is 2-fold: Tensioning the backstay increases overall tension in the fore and aft plane, loading the headstay and reducing sag. It also has the effect of bending the mast (NOT raking it because you don't change the headstay!), which flattens the mainsail. Note the top of the rig moves aft while the middle moves forward, so the rig CE changes very, very little. This is a good thing because as the breeze builds, the headstay will sag more, and the mainsail will need less power. Adding backstay which bends the mast accomplishes both goals!

So, the idea of playing the backstay is to keep it softer in the lght air, add some in the puffs, ease in the lulls, etc. Or "season to taste" if conditions are steady.

For most boats these days, about the only rake adjustment we make while sailing is that we ease the backstay all the way when going downwind to allow the top of the rig to go forward, which will reduce WEATHER HELM-when sailing downwind you want to elminate any tendency of the boat to head up, since your destination is "down". There is an added benefit of getting the roach of the mainsail slightly higher in the air where the breeze is stronger and less affected by the rigging, other boats, etc. It may seem small, but there is a very real effect.

In the old days (70's), many race boats had adjustable headstays AND backstays, so that in addition to doing all the things mentioned above, they could easily adjust rake while sailing to more accurately balance the helm. In the trend towrds simpler boats these days, this is much less common, and many racing rules allow only one adjuster for fore and aft rigging-and most boats choose the backstay adjuster. So today, mostly we set up the rake at the dock, use the backstay for bend, and rake forward when going downwind as the only rake adjustment. It is not unusual for boats like the J105, and others to have several headstay length settings (rake adjustments) for different conditions, but it is changed only between races-not during.

Sorry to be so long-winded, but this is good stuff to understand. Thanks for your patience!
Cheers!

S