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Old 29-10-2012, 09:57   #1
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Mast tie rod adjustment/limber hole in mast

This Winter I have dropped my mast for inpection, reconditioning and replacement of lights and wires. Before stepping the mast in Spring, I completely loosen the mast tie rod, step the mast and tune the rig. This tightens the tie rod and generally I do nothing else. Is there a better procedure that allows one to adjust the tension to a pre-determined/theoretical tolerance? Also, the base of my mast does not have a limber hole. Should one be drilled and if so, at what height from the mast step. The mast is a double spreader Isomat, 52 feet and keel stepped. All suggestions will be greatly appreciated.
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Old 02-11-2012, 11:01   #2
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Re: Mast tie rod adjustment/limber hole in mast

I don't understand why you would loosen the tie rod in the 1st place the tie is there to stop the deck from flexing when sailing! So why would you have to redo every time. I would think it should be set and left alone, unless there is vertical movement between your deck and keel, in which case there is a more pressing issue you have to deal with. When I set my rig tension I tighten just enough to keep it straight. when you get pressure on on the windward side the leeward shrouds will look like they are loose, because the windward shrouds will stretch some what this is normal. Just make sure there are toggles above and below your turnbuckles. they prevent damage to your shroud when it is swinging in the breeze.
The limber hole should be as low as you can get it on the back side of the mast unless your mast stands perfectly vertical and step is horizontal. there should not be that much water getting into the mast even in heavy rain. I hardly if ever see any wetness during or after rain even driving rain
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Old 02-11-2012, 11:08   #3
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Re: Mast tie rod adjustment/limber hole in mast

I wont answer your tie rod question. I'll leave that up to someone who knows what to do. However the limber hole. Does the mast step have a drainage hole, or trough. If not then yes, you should have some way to drain away the water. Perhaps a small trough cut out on each side of the mast step would be best.
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Old 02-11-2012, 12:16   #4
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Re: Mast tie rod adjustment/limber hole in mast

Mike and DeepFrz, thank you for the replies. I understand the purpose of the tie rod, but the last time I restepped my mast, I adjusted the tie rod in a loosened position, stepped the mast, tuned the rig and rechecked the tie rod which then was snug. The original rigging manual for my boat recommended that specific procedure with the exception that the tie rod needed to be manually adjusted to snug after the rig was tensioned. That leads me to believe I didn't get the tie rod loose enough initially which may have effected the dynamics of my cabintop. Does this make sense? Secondly, my mast has a substanital rake as engineered for the boat and with the wedges at the partners and the blocks at the base of the mast I am not certain that all the water that enters the mast after a substantial rain is quickly drained. There are two limber holes in the mast step which I keep clear and do drain the water, albeit slowly, as it collects. My concern is that the base of the mast is perfectly mated with the mast step allowing water to collect longer than necessary. Ergo, the limber holes. Any ideas?
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Old 02-11-2012, 12:50   #5
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Re: Mast tie rod adjustment/limber hole in mast

I can't understand how the tie rod is snug after tuning the rig. The tie rod is usually from the mast to the coachroof. How can that distance (the distance between the attachment point on the mast and the point on the coachroof (often the collar) increase when tuning the rig?
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Old 02-11-2012, 12:59   #6
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Re: Mast tie rod adjustment/limber hole in mast

The slots/holes/grooves whatever in your maststep need to drain water that enters through halyard slots in the mast, naturally and by gravity without your attention. All you should need to do is pump the bilge occasionally. So, yes, there must be limber holes of some sort.Tie rod, whether mast to keel or deck shroud to inner pan should be set up tight, but without undue stress, ( try to feel the amount that you're screwing the deck and inner pan together) at the dock. The shroud tie rods may require additional tightening on alternate tacks under sailing conditions, done a little at a time on each tack, until the lee shroud is just slightly slack on a reach in a stiff breeze. This no rocket science, just a feel for the job that the standing rigging is to do.
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Old 02-11-2012, 13:11   #7
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Re: Mast tie rod adjustment/limber hole in mast

On a keel stepped mast, The hull sides are pulled together by the shrouds as they are tightened which causes the deck to buckle upwards, almost always. The tie rod holds the deck in place helping the to keep the hull sides from collapsing inward. The tie rod should be finger tight so it just starts pulling the deck down before the shrouds are tightened. Because the shrouds are attempting to pull the hull sides inward and compressing the deck longitudinally, the tie rod will get addidtional tension as the shrouds tightened. It's not a precise tension, you are just trying to keep the deck from pumping which doesn't take large hardware or get all that much pressure.
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Old 02-11-2012, 16:18   #8
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Re: Mast tie rod adjustment/limber hole in mast

Quote:
Originally Posted by roverhi View Post
On a keel stepped mast, The hull sides are pulled together by the shrouds as they are tightened which causes the deck to buckle upwards, almost always. The tie rod holds the deck in place helping the to keep the hull sides from collapsing inward. The tie rod should be finger tight so it just starts pulling the deck down before the shrouds are tightened. Because the shrouds are attempting to pull the hull sides inward and compressing the deck longitudinally, the tie rod will get addidtional tension as the shrouds tightened. It's not a precise tension, you are just trying to keep the deck from pumping which doesn't take large hardware or get all that much pressure.
Thanks Roverhi, that was the answer I needed in re: the tie rod. Thanks also to everyone for their input.
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Old 20-01-2016, 13:56   #9
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Re: Mast tie rod adjustment/limber hole in mast

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Originally Posted by Vasco View Post
I can't understand how the tie rod is snug after tuning the rig. The tie rod is usually from the mast to the coachroof. How can that distance (the distance between the attachment point on the mast and the point on the coachroof (often the collar) increase when tuning the rig?

Compression of the beam of the boat towards the inside.
Since the coach roof is somewhat convex, the tendency is to raise the roof! Literally!


Sent from SV Cloud Duster
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