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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

tension on the shrouds

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michael.j.wenger
1st Mate

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USA
45 Posts

Initially Posted - 09/14/2015 : 07:20:39

How much tension should be on the shrouds, particularly the lowers? I was out this weekend and, close-hauled on a starboard tack, noticed that the leeward shrouds were hanging rather loose. Should there be more tension and should I be adjusting tension with a gauge? Many thanks (as always!) in advance!

Michael Wenger
Norman OK (Lake Thunderbird)
"Sea of Tea" (SK/TR)

pastmember
Master Marine Consultant

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2402 Posts

Response Posted - 09/14/2015 : 15:13:46

A nice twang, no thwunk. The thing that matters the most is to have both sides the same. There is no answer because "loose rigs are fast rigs" and loose rigs can cause pumping or mast inversion. I sailed in strong wind a lot and liked a tight rig but leeward shrouds and stays should be visibly slack when in a breeze. This always raises the issue of wire whipping/swaging stays to the spreaders, as long as you are properly connected to the spreader slack is ok.

Frank Hopper

islander
Master Marine Consultant

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4034 Posts

Response Posted - 09/14/2015 : 15:40:25

It's normal that the shrouds get loose on the leeward side, I'm a little surprised that you just noticed this. A Loose gauge is helpful in that It will tell you if both sides have equal tension and also that you haven't over tensioned any shrouds but it isn't necessary to tune the rig with them. Here is a Tec tip on how to do it.http://www3.telus.net/sail/sj23/f_rigging_tips/f24.html
If you have the Loose gauges then a good ball park numbers to double check your tuning would be
Uppers-32
Aft lowers-20
Forward lowers-24
The forstay and backstay will have the most tension around 35-36

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Stu Jackson C34
Admiral

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844 Posts

Response Posted - 09/15/2015 : 10:43:00

All Catalina masthead single spreader rigs have a great tuning guide in the boat MANUALS.

It is one of the best I've ever read.

It's simple. It does not require any gauges.

It has worked for us since we bought our C22 in 1983, our C25 in 1987 and our C34 in 1998.

Stu
1986 C34 #224 "Aquavite"
Cowichan Bay, BC Maple Bay Marina
(formerly San Francisco)
(formerly C25 #2459 "Capricorn Two")

michael.j.wenger
1st Mate

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USA
45 Posts

Response Posted - 09/16/2015 : 11:16:18

Many thanks, all. As usual, great information all around. And I've now got a manual on the way. Thanks again!

Michael Wenger
Norman OK (Lake Thunderbird)
"Sea of Tea" (SK/TR)

Captain Max
1st Mate

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USA
87 Posts

Response Posted - 10/04/2015 : 14:22:57

Scott, where did you get numbers for loose gauge? We tuned our Cat 25's a couple of weeks ago, but with much lower numbers. We were just guessing though.

Captain Max
"Wyvern"
84 Cat 25 FK
Bayview Marina
Dallas Tx Area

Edited by - Captain Max on 10/04/2015 14:24:32

pastmember
Master Marine Consultant

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2402 Posts

Response Posted - 10/04/2015 : 15:53:43

quote:
Originally posted by Captain Max

Scott, where did you get numbers for loose gauge? We tuned our Cat 25's a couple of weeks ago, but with much lower numbers. We were just guessing though.

There are two Loos, one for smaller diameter shrouds and one for big ones. The numbers are pretty arbitrary so they do not correlate much between the two. On my model I would stand at the mast step, measure shoulder height on all shrouds and the gauge pulled all the way to the very end on the uppers when I was happy. and yes the lowers should be a little less with the aft lowers the least. ... IF you have a split backstay and an adjuster, if not make the aft and forward lowers the same.

Frank Hopper

Edited by - pastmember on 10/04/2015 15:57:48

Steve Milby
Past Commodore

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5909 Posts

Response Posted - 10/04/2015 : 17:39:28

The manufacturer's instructions for how to use a Loos gauge can be found at this link.
http://loosnaples.com/how-to-use-pt-series-tension-gauges

In those instructions, the manufacturer says, in bold type:"Specific tension requirements for your application must be obtained from the boat, mast, or sail manufacturer or the manufacturer of the product on which the cable is used."

In the absence of reliable numbers that are specific to the boat, I think the value of a Loos gauge is dubious.

I have never seen or heard of any specific numbers that have been provided by Catalina for the tensions that should be used on a C25. I have seen boats that were damaged by over tensioning the shrouds by gung ho racers who didn't understand how to tune the rig correctly.

But, think logically about what's important. The mast should be erect, it should be straight, and the shrouds should be tight enough to hold the mast securely in that position, and to prevent it from moving excessively fore-and-aft or from side-to-side in heavy chop. You don't want a loose rig that slams back-and-forth or from side-to-side in a seaway.

There are several basic principles that should be followed in tuning a rig without a backstay adjuster.

1. You should begin by making the mast plumb, both fore and aft, and from side to side.

2. Take all the slack out of all the shrouds. Don't use any tools to tighten the turnbuckles. Just tighten them by hand.

3. From this point on, start tightening the starboard side upper shroud by 4-5 turns, and then tighten the port side upper by the same number of turns. Next, alternately tighten the forward lowers by the same number of turns. Then tighten the aft lowers by the same number of turns. Sight up the mast kerf to be sure the mast is still straight. Repeat the same process until the mast stays are snug, but not bar-tight. Tighten the uppers an extra turn or two, because the uppers are longer, and they will tend to stretch a little more under load.

Tighten the forestay and backstay alternately by equal numbers of turns until they are snugged, but not bar-tight. The forestay should deflect slightly, but not alot, when you pull on it. You want the forestay firm enough so that it doesn't sag excessively when under sail in a strong wind.

4. Sail the boat in winds about 10-12 kts. When the boat is sailing closehauled, sight up the kerf of the mast and see if it is still straight under load. Look at the leeward shrouds. They should be slightly relaxed, without being really loose.

Take note of how much weather helm you feel in the tiller. You should feel a very light weather helm. If it's too light for your liking, or if you feel lee helm, then go back to the dock and ease the turnbuckle for the forestay by 2-4 turns, and tighten the backstay turnbuckle by the same number of turns.

If you feel too much weather helm, then ease the backstay turnbuckle, and tighten the forestay turnbuckle by an equal number of turns.

Tilting the rig forward reduces weather helm. Tilting it aft increases weather helm.

To summarize, good rig tuning doesn't mean tuning it bar tight or sloppy loose. Just get it straight, approximately plumb, and limit it's movement in a seaway.

None of that requires the use of a Loos gauge, and, IMO, a Loos gauge doesn't really add anything significant to the process. If you do all that, the rig will be well tuned by any reasonable standard.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

Edited by - Steve Milby on 10/04/2015 18:22:47

islander
Master Marine Consultant

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4034 Posts

Response Posted - 10/05/2015 : 07:45:51

quote:
Scott, where did you get numbers for loose gauge?

From this forum a few years ago. They were posted by a well respected member. As I said they are just ball park figures. I did my rig after replacing my standing rigging and did it the way Steve has described. For me it was frustrating because if you tighten one shroud it will tighten or loosen the others so it was a constant battle going round and round adjusting little by little. Then when you think all is good you lay on your back and look up the mast just to see an S curve in it port to starboard. GRRRrr. So back to square one. The Loose guages are just another tool for checking the tension on the wires when you are done. They should be the same on both sides and the mast plumb. The wires have a breaking strength and you would be amazed at how easy it is to exceed that number. You also can be totally in tune but have way too much tension in all of the wires. This result in driving the mast down and compressing the deck under the mast step. If the wires are too loose the mast will sway back and forth when under pressure from the sails. This works your mast step back and forth and you end up with leaky mast step bolts. For a first timer it took me a long time to finally get it right. Now 3 years later the new wires have stretched some and my rig is loose so next year when the boat gets launched I should go tighten them some. FYI do this while the boat is in the water and relaxed. If its up on stands or a trailer the hull will be flexed. This would change all the tension on the wires when you put it back in the water.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Edited by - islander on 10/05/2015 08:12:26

Derek Crawford
Master Marine Consultant

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3324 Posts

Response Posted - 10/07/2015 : 12:51:53

I probably had the reputation of carrying the loosest rig! If you are a determined racer then "loose is fast" should be your creed. In addition to the numbers quoted above (20,24,32 - which is what I used) I had 8"-10" of sag in the forestay (this gives you a "soft" entry and powers up the genoa as well as giving you a larger "groove". I had a good backstay adjuster, so my backstay "waved in the breeze" but when cranked on it tightened the forestay and the backstay to depower in higher winds. The leeward shrouds when going to weather looked like wet spaghetti and tended to scare people when they first sailed with me!
This tuning enabled me to sail well to weather, but off the wind she became almost a rocket ship...
If you are a non-racer you will probably tune tighter.

Derek Crawford
Chief Measurer C25-250 2008
Previous owner of "This Side UP"
1981 C-25 TR/FK #2262 Used to have an '89 C22 #9483, "Downsized"
San Antonio, Texas

islander
Master Marine Consultant

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USA
4034 Posts

Response Posted - 10/07/2015 : 15:25:45

Thanks Derek for refreshing my memory on where I got those numbers.

Scott-"IMPULSE"87'C25/SR/WK/Din.#5688
Sailing out of Glen Cove,L.I Sound

Steve Milby
Past Commodore

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USA
5909 Posts

Response Posted - 10/07/2015 : 15:31:57

That's the way I tuned my C25 with an adjustable backstay, too, but you wouldn't want to do that with a fixed backstay. That's the advantage of a backstay adjuster. A loose rig is faster downwind, but a taut rig is faster to windward. A backstay adjuster lets you completely change the tuning of the rig instantly, on the fly, each time you round a windward or leeward mark. If you don't have a backstay adjuster, then the best recourse is to tune the rig for good windward performance.

Steve Milby J/24 "Captiva Wind"
previously C&C 35, Cal 25, C25 TR/FK, C22
Past Commodore

Edited by - Steve Milby on 10/07/2015 15:36:29

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