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Standing Rigging Question

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existentialsailor
Master Marine Consultant

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USA
1180 Posts

Initially Posted - 10/29/2004 : 09:56:27

The standing rigging on the port and starboard sides of boat sometimes is slack on one side when under sail. Not in light winds, but in moderate winds. It is always the side that is closest to the water as I am heeled over at about 20 degrees, (hopefully, I'm using the correct term). Am I wrong in concluding that this indicates it is not correctly tuned? I've never tuned rigging before.

Any recomendations on where to get information on how to do this.

All suggestions appreciated.

Thank you.

Rick

Edited by - on

austin72
1st Mate

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48 Posts

Response Posted - 10/29/2004 : 10:54:07

Without seeing how much slack you're experiencing, it's difficult to say whether you're rigging is properly tuned or not. That said, the windward rigging always bears the brunt of supporting the mast, so seeing a little slack in the leeward rigging is normal in my opinion. The slack is simply from the mast flexing under loads from the sail.

You may want to have someone knowledgeable take a look at your rigging and get an informed opinion. Or, the link below references an article Bill Holcomb wrote awhile back regarding tuning.

http://www.catalina25-250.org/tech/tech25/snkmast.html

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 10/29/2004 : 11:03:53

The people who manufacture the LOOS tunning tool maintain that a rig must be tight on all sides under all loads to distribute the load to all of the chain plates rather than to just some of the chain plates. That said, most of us run with slack leeward rigging because a loose rig is more adjustable while sailing.

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Bill Holcomb
Admiral

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USA
769 Posts

Response Posted - 10/29/2004 : 11:20:55

If you tighten the standing rigging to the point that the leeside shrouds do not slacken slightly in moderate breezes, the rigging is too tight. Your Capri 25 has the same setup as a C25......forestay, backstay, one upper shroud on each side and two lower shrouds on each side. Here's the url to the techtips section that has rig tuning thoughts. http://www.catalina25-250.org/tech/tech25/snkmast.html If you tune your Capri 25 like the article says, you'll be pretty close for recreational sailing. Of course, if you are racing, you'll adjust things for specific breeze conditions on each day.

Bill Holcomb - C25 Snickerdoodle #4839

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Steve Milby
Past Commodore

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USA
5913 Posts

Response Posted - 10/29/2004 : 13:33:13

As you can see, there are differing opinions on shroud tensions. Personally, I usually tension mine so that the lee shrouds relax very slightly in winds between about 15-20. If they are over-tightened, you could damage the boat. If they're too loose, the rig can whip around in rough water.

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 10/29/2004 : 16:16:47

I set up my shroud tension as Steve Milby has described. I set my forestay and backstay turnbuckle tension for a light air run, and use a backstay tensioner from there.

I suspect that the shroud slack you (we) are seeing on a beat in heavy air comes mostly from hull flex, along with a bit of rigging stretch and an even smaller amount of mast compression.

-- Leon Sisson

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Derek Crawford
Master Marine Consultant

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USA
3324 Posts

Response Posted - 10/29/2004 : 19:03:22

Shucks - my leeward shrouds look like wet spaghetti! Just ask Frank!
Derek

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 10/29/2004 : 20:36:06

There's an old saying about racing engines that also applies to sailboats.
"Loose ones go fast... for awhile anyway".

My lee rigging will get a litle slack above 10-15 kts... I run my aft lowers a bit looser than the forwards and the uppers. Like Leon, I whump the backstay tension up in heavier air.

If you run loose at all, make sure your spreader tips have retainers for the upper shrouds. I think one of the members here lost their rig when a lee upper shroud came off the spreader.

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Steve Milby
Past Commodore

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USA
5913 Posts

Response Posted - 10/30/2004 : 09:10:41

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Shucks - my leeward shrouds look like wet spaghetti!<hr height="1" noshade id="quote"></blockquote id="quote"> If you don't have an adjustable backstay, then all the shrouds should be tensioned the way I previously described. If you have an adjustable backstay, then the aft lowers and the headstay should be "like wet spaghetti." When the backstay adjuster is eased, the jib has a very full, powerful shape for sailing off the wind. When the adjuster is tensioned, it pulls the top of the mast aft, which takes the slack out of the headstay and flattens the jib. It also pulls downward on the top of the mast, which causes the mid-section of the mast to bow forward. That flattens the mainsail. All that helps the boat point to windward. In order for all that to work, the aft lowers have to be adjusted loosely when the backstay adjuster is eased, but they should become taut when the adjuster is tensioned.

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 10/30/2004 : 11:22:03

Another effect of very tight rigs that some sailors experience is "mast pumping"--when you're moored, sails furled, and the wind pipes up, the mast starts a rythmic thumping from a slight forward bend to an aft bend (or side to side). It's not very good for the rig and a little disconcerting to the people in the cabin. I suspect it mostly has to do with the upper shrouds being excessively tight--they should always be somewhat tighter than the lowers.

On the other hand, I've heard or read that boats that stay on moorings where there's fairly constant wave action should have fairly tight shrouds to keep the mast from yanking on them as the boat rocks--since that's where it'll be 95% of the time.

There, does that clear everything up?

If you're not seeing slack until the wind is around 12 kts or above, I'd say you're not too loose or too tight.

Edited by - Dave Bristle on 10/30/2004 11:24:34

existentialsailor
Master Marine Consultant

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USA
1180 Posts

Response Posted - 10/30/2004 : 16:33:37

Thank you everyone for the responses and tips. I definately think they need some adjustment from what I'm seeing as sometimes there is noise coming from the plates (Chain plates? rather large angle aluminum) that the two forward lower shrouds are attached to. These two are the slackest (though not at the same time as I described) slack enough that the plates below the deck are easily movable when that side is leeward. The two upper shrouds are also slack but not half as much as the forward lower shrouds as you can not move the plates. Since it's coming out of the water next week, I'll have to address it next season or perhaps when it is in its cradle (the mast stays up for the winter). I see a tension guage in my future, maybe even new riging if on inspection I don't like what I see.

Again, my appreciation for all the help on this subject.

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 10/30/2004 : 21:50:56

<blockquote id="quote">quote:<hr height="1" noshade id="quote">[i]I see a tension guage in my future, maybe even new riging if on inspection I don't like what I see.
<hr height="1" noshade id="quote"></blockquote id="quote">

I've never noticed movements in the chainplate anchors--I'd be concerned that it would allow leakage and rotting in the plywood core. I'm going to look closer at mine tomorrow--I may have more to say about it then. (Hear the collective groan...)

I've never used a gauge, although I've had a few people who know more than I do check my setup. With what you're describing, I'd start by tightening the forward lowers enough so that the aft lowers slack before the forwards. Bill Holcomb's guide is a good approach, but incremental adjustments between outings is a good idea. To determine that my upper shrouds are adjusted evenly, I check to see that the mast is plumb (side to side) by hooking a wrench to my main halyard shackle and seeing how it hangs. To check the lowers, I tap them with the wrench and listen to the low-pitch vibration, and sight up the mast to verify that it's straight. The two forwards should be equal, and the two afts should be equal, but the forwards not looser than the afts.

Using the wrench-on-the-halyard technique, I check to see that my mast is tipped aft enough that the wrench hangs 3-4" back at boom level. That gives me a very light weather helm, but every set of sails will vary that finding. If you have lee helm (the boat turns down-wind when you let go of the tiller), you should tip the mast further back (ease the forestay, tighten the backstay, and adjust the lowers slightly). I had to have my backstay shortened to rake the mast far enough to get weather helm. But you can only determine how far by trying it, sailing with it, and checking the helm balance.

Edited by - Dave Bristle on 10/30/2004 22:03:24

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