Shrouds loosening

[Mougly]

Hello all

After going out a few times in brisk winds, I adjusted the tension on the shrouds as they had stretched a bit, today I went out again and noticed that when I heel to Starboard the outer leeward shroud is very slack but when I heel to Port the leeward shroud loosens but holds more tension than the other side. the shrouds were adjusted the same way and the mast was strait....is there a reason why that would happen (same degree of heel).
Also my inner shrouds on the leeward side go very slack where they seem to flap a little is this normal.

Cheers

 

[RichH]

Possibilities:
1. The swages in the terminal ends are slipping
2. The chainplates and their attachment 'bases' are pulling free from the hull

Loosening shrouds is a very BAD sign and at worst may be symptomatic of a rig thats about to fall down.

 

[Joseph Shirley]

Check and make that your turnbuckles are not backing off. Each turnbuckle should have either a cotter pin or something similar, or a locknut to prevent them from turning. If the have retaining pins or locknuts reread the above post.

Good luck

Joe S

 

[tsmwebb]

Also, could be compression. If the mast is deck stepped the mast step, main bulkhead or compression post could be soft or if keel stepped may also have a weak step. Is this new wire? While Rich is right that this could be a sign of something very serious it might be that you just didn't tune the rig all that well.

--Tom.

 

[RichH]

in addition to Tom & Joe's additions:

How long ago did you raise/install this mast? Sometimes on a deck-stepped mast the butt end of the mast doesnt fully 'set' into the 'socket' on the coach roof and it takes time for it to 'relocated' and fully 'settle in'.

So, now you should check the following: rigging terminal connectors, turnbuckle cotter pins, mast connection with either the 'coachroof' connection, the chainplates and their hull attachments, the compression post for rot on both ends, (and/or if the mast is keel stepped if the mast butt is sinking into the keel/bilge due to 'rot').

 

[Mougly]

Thank you all
The mast was stepped about 3 weeks ago, it is a deck stepped mast (hinge type), there is no rotting anywhere, the turn buckles seem to be fine with lock nuts on all, the shrouds are not new (not sure how old). I suspect that the the rig was not tuned so I will try to tighten the shrouds and let you know what happens next.

Hopefully it is just a mater of fine tuning the rigging and nothing more serious.

 

[NC-C320]

Loose Shrouds

For what it is worth:

In the owner's manual for Catalina 320 and in the section on mast tuning, it plainly states that when properly tuned, the leeward shrouds should begin to go slack at 15 degrees heel. Also, on my previous Kells 28, this was also the case, and I have read similar words in other articles on rig tuning.

So some slack on leeward side under heavy loading seems to be ok. However, if after repeated tightening a bit, you notice significant re-loosing of shrouds, something else might be going on. Also, if mast is properly centered, any loosening should be approximately the same on both sides, it would seem to me.

Caution on tightening shrouds and stays, you can overdo it and severely damage the boat or the rig.

 

[RichH]

Basic rig tension should be about 15% tension in the shrouds ... a bit more in the backstay.
Archive of how to precisely tune the rig WITHOUT a tension gage: http://forums.sbo.sailboatowners.com/showthread.php?p=643617

hope this helps

 

[bffatcat]

loose shrouds

The rest of the guys have told u what to look for. What I can add is: Tighten the Uppers
so theyre snug. Make sure they are pinned, lock nuts snug if u have them Put some tape on the threads to guard against slippage. Check your chain plate bolts make sure they are tight Go out for a sail the lee Uppers should have some slack the weather uppers should be taught
this is normal. After your sail look for and note any loosening in uppers and chain plates.
Report back to the board

 

[Ross]

Re: loose shrouds

Put some index marks in the shroud/swage junction and on the chainplates. Everything will be guessing without a reference point.

 

[Stu Jackson]

Index marks are a good idea. What we use with our open body turnbuckles is a yellow crayon.

 

[Mich222]

Do these tuning instructions apply equally to both a masthead sloop rig and a fractional sloop rig?

 

[RichH]

Do these tuning instructions apply equally to both a masthead sloop rig and a fractional sloop rig?

For 'basic' tuning, yes. 12-15% tension in all shrouds and stays

Of course, you should then adjust to 1. keep the mast 'straight' as seen when the boat is at maximum normal heel while sailing. 2. to match the 'luff curve' of the headsail when at maximum normal heel when going to windward/beating.

Other.
This ignores mast 'pre-bend' (bowing the center of the mast 'forward') which is a somewhat 'advanced' tuning to prevent 'mast pumping' (harmonic oscilations).