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Tuning Standing Rigging on Catalina 25

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Ensign906
Deckhand

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USA
1 Posts

Initially Posted - 07/06/2012 : 08:15:26

A friend recently purchased a pre-1980 model Cat25 and I am assisting in tuning the shrouds. I am familiar with a Loos guage and would like some input on the tensions for the uppers and lowers for average wind conditions of 10 -15 mph. The mast is in column and the kerf is wirtually perfectly straight. Preliminarily we set the uppers at 35# tension and both the forward and aft lowers at 30# tension. We took a test sail in an 8 - 10 mph breeze, and sailing close-hauled the leeward shrouds were hanging very loosely, so I suspect that the tensions we used are too low. We have about 1 - 2 inches of aft bend at the top of the mast, and we had a very slight amount of weather helm -- with no hand on the tiller the boat crept up to windward. Can someone provide me with some specific Loos guage tensions that we should use as a starting point?

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Sloop Smitten
Master Marine Consultant

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USA
1181 Posts

Response Posted - 07/06/2012 : 08:48:25

I know I set my uppers at 35 on the Loos gauge and the lowers at 30 just like you did. There should be some slack in the leeward shrouds under sail. If you think they are too loose try a 40/35 combination. I usually get them close and then adjust one of the uppers visually when under sail to what I feel is a proper amount of looseness. Then I take a reading on that shroud and adjust them both to the reading I took. It is a give-and-take process since if you tighten one side up the other side will change. Then I set the lowers 5# less. Then you have to check the uppers again as adjusting the lowers can change the uppers. Give-and-take, give-and- take . . .

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sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Response Posted - 07/06/2012 : 10:04:38

Mine are all in the mid-teens! I sail on an inland lake with light wind. Should I adjust my lowers to 30 too?

Could this explain the cracks in the gelcoat at the mast step?

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Sloop Smitten
Master Marine Consultant

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USA
1181 Posts

Response Posted - 07/06/2012 : 10:40:09

Mid-teens might be fine in light winds. It would be to loose for my taste but it is an individual preference. I guess a rocking mast could cause cracks around the mast step but I would suspect someone went overboard when tightening the mast step bolts, overtightened the shrouds/stays or water intrusion to the roof deck (softening) as a more likely cause.

Edited by - Sloop Smitten on 07/06/2012 10:41:48

Steve Milby
Past Commodore

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USA
5902 Posts

Response Posted - 07/06/2012 : 10:56:32

Does your boat have a backstay adjuster? If so, it is tuned differently.

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sethp001
Mainsheet C-25 Tech Editor

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814 Posts

Response Posted - 07/06/2012 : 13:39:32

Yes, I have a back stay adjuster. What's recommended for me?

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Steve Milby
 Does your boat have a backstay adjuster? If so, it is tuned differently.
<hr height="1" noshade id="quote"></blockquote id="quote">

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Ape-X
Admiral

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USA
662 Posts

Response Posted - 07/06/2012 : 13:47:16

search the site for tuning mast, but basically tune the mast with lower back shrouds looser than front. You want the mast to be in column with the adjuster off, and a slight bend with the adjuster on. The backstay cranked on will bend the mast middle section forward, tightening the lower back shrouds.

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Steve Milby
Past Commodore

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USA
5902 Posts

Response Posted - 07/06/2012 : 17:05:43

A backstay adjuster on a boat with a masthead rig can only work if it has a considerable amount of slack when it's eased. If there's no slack, the combined effect of all the stays will be to hold the mast straight and in column. The forward lowers and uppers should be relatively taut, but the forestay, backstay and aft lowers should be quite loose. As tension is applied to the backstay adjuster, the aft lowers should gradually become taut.

I used the following method to tune my C25 rig with backstay adjuster, and found it very fast to windward, but where it really helped was downwind and light air. With one flick of the wrist, you can, in essence, re-tune the rig on the fly, from taut to loose.

http://catalina-capri-25s.org/racing/racing_tips7.asp

Edited by - on

awetmore
Master Marine Consultant

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USA
1144 Posts

Response Posted - 07/07/2012 : 20:31:34

Thanks for the thread. It got me to adjust my rigging a little bit this morning (slackened the forestay and rear two lower shrouds) and based on my GPS track it looks like my boat is pointing a bit higher. I won't really know until I get some time with it on the lake or Tuesday's race.

I also have an adjustable backstay, but always had to run my rear lower shrouds with higher tension than I'd want because they are just a tiny bit too short. A few weeks ago I got small extensions that bring them up about 2cm, and now I can adjust them properly.

Before my tuning this morning adjusting the backstay didn't do a whole lot. Now I have a much greater range of adjustment and I can see the mast curving backwards when it is highly tensioned.

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