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Old 23-08-2015, 22:11   #1
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Tuning Rigging

I have a 48ft Cutter Rig yacht and have recently completed a major job of reinstalling my port main chainplate and a large portion of the main bulkhead. This was due to an unseen leakage around the chainplate over a long period time, effectively rotting the ply bulkhead out and the whole chainplate then detaching in 30-40 knots with a 20M deck stepped, triple spreader mast attached.
Suffice to say I managed to down sails, save the mast , made it to port and have completed the repair, replacing parts of deck, bulkhead and ensuring this never happens again

Whilst the standard advice is use get a rigger to tune your mast, I would like to understand the basics of what tension I tighten the shrouds up to as this major chainplate has Lower, Inner and Upper shrouds connected to it.

I have ensured the mast has the correct rake or bend in it as originally set up (is tensioned via the fixed back stay). I have tensioned the stays to ensure the mast is straight. I have tried measuring the thread left on each bottle screw on the Starboard side stays to ensure the port side is similar or close. My question is "how tight or tensioned" should the stays be? Like a "guitar string" tight ?, (poor nautical terminology) and should all stays be of equal tension? The rig is standard S/S wire with dual forestays (one used for Self Furler) , Inner Forestay, Baby Stay, Running Back stays and 2 x secondary lower shrouds and separate chain plate located aft of main chainplate. (probably what saved the mast!)

I know "use a Rigger is the right answer" but if I'm cruising in remote areas as planned, need to effect a repair again for the mast or some other reason to undo rigging, I would like to know what the minimum set up of a rig is.

Thanks for any advice....... as always learning.
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Old 23-08-2015, 22:31   #2
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Re: Tuning Rigging

Get the rigger to explain it to you.
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Old 23-08-2015, 23:01   #3
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Tuning Rigging

The Riggers Apprentice suggests starting low and that when dock tuning stopping once the lower shroud will play a true "note" and that then tension should go up slightly with shroud height.

When sailing in 25+ winds the lee shrouds should loosen but not be sloppy.

One of the better books onboard.


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Old 23-08-2015, 23:54   #4
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Re: Tuning Rigging

That is a pretty big and complex rig to start your tuning education on!!

You didn't mention whether it was straight or swept-back spreaders, nor if it was masthead or fractional rigged, and both of those will influence the process.

IIRC, Selden has tuning instructions for some of their rigs on line, and they are often similar to what you have described. There are likely other on line sources for tuning instruction as well. Again IIRC, Selden uses a simple means of measuring stretch in the wires to guide you to the proper tension, so no guitar tuning fork will be needed.

But, the process of progressing from one shroud to the next is not intuitive, so do get some sort of knowledgeable help if you can. The bottom line is that the mast should have the proper prebend fore and aft, the proper static rake, and should stay straight athwartships under load on both tacks, with the leeward shrouds not going too slack.

Meanwhile, good job in saving the mast! Those bloody things are pretty pricey.

Good luck,

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Old 24-08-2015, 06:29   #5
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Re: Tuning Rigging

+1 to Jim's post.

Do a good dock tune first. Plenty of stuff online. Don't expect port and stb turnbuckles to be the same, measure from the masthead and then measure again. Get the mast straight, and the longer shrouds tighter. Watch that the mast partners (keel stepped masts) don't force the mast out of true. Intermediates will be the slackest, caps and lowers tighter.

Then go sailing with a decent crew. It's hard to hurt the rig too badly if you take things easy. Start out in a steady 10-15 knots with a flat sea, slowly tightening down the lee side as you tack to windward, sighting up the mast after every adjustment. It's not rocket science, and considering how poorly most cruisers rigs are tuned you can't do much worse yourself given time and a slow methodical approach and a bit of reading.

Things get harder if it's swept spreader, but inline is pretty logical.

Once things look good in 15 knots try twenty, and then start reefing to see how it changes things. Read all the online guides, count turns. Caps tighter than intermediate, lowers often Need to be tight on a triple spreader rig, and no slop, in the Lee shrouds unless you are fully powered up to windward, even then not much.

Be careful with spreader droop. After each bout of big adjustments, check the spreaders haven't been pulled down, or slipped, and re-secure. Discontinuous is a bit safer in this regard, but then you end up spending a lot of time aloft..


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Old 24-08-2015, 07:07   #6
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Re: Tuning Rigging

Most pro riggers I know don't use a tension gauge, but for us amateurs I think its a good idea. This allows you to hit a specific tension and/or confirm that port & stb sides have equal tension.
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Old 24-08-2015, 07:55   #7
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Re: Tuning Rigging

There is a very fine Selden download pdf that explains all basic styles of tuning. Look it up.

I tune masts nearly always in line for in line spreaders and/or in-mast furlers. I give more pre bend in swept spreaders configs, AS A GENERAL RULE. I measure tension by whatever method is available, I like Loos meter, when there is one at hand. If not, I use the tape method.

Cutter rigs can be more difficult as you may want to have the cutter stay tight ... which is at times difficult to achieve with in line spreaders.

Look up at Selden, I think you will like their info.

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Old 24-08-2015, 09:16   #8
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Re: Tuning Rigging

Quote:
Originally Posted by foletti View Post
I have a 48ft Cutter Rig yacht and have recently completed a major job of reinstalling my port main chainplate and a large portion of the main bulkhead. This was due to an unseen leakage around the chainplate over a long period time, effectively rotting the ply bulkhead out and the whole chainplate then detaching in 30-40 knots with a 20M deck stepped, triple spreader mast attached.
Suffice to say I managed to down sails, save the mast , made it to port and have completed the repair, replacing parts of deck, bulkhead and ensuring this never happens again

Whilst the standard advice is use get a rigger to tune your mast, I would like to understand the basics of what tension I tighten the shrouds up to as this major chainplate has Lower, Inner and Upper shrouds connected to it.

I have ensured the mast has the correct rake or bend in it as originally set up (is tensioned via the fixed back stay). I have tensioned the stays to ensure the mast is straight. I have tried measuring the thread left on each bottle screw on the Starboard side stays to ensure the port side is similar or close. My question is "how tight or tensioned" should the stays be? Like a "guitar string" tight ?, (poor nautical terminology) and should all stays be of equal tension? The rig is standard S/S wire with dual forestays (one used for Self Furler) , Inner Forestay, Baby Stay, Running Back stays and 2 x secondary lower shrouds and separate chain plate located aft of main chainplate. (probably what saved the mast!)

I know "use a Rigger is the right answer" but if I'm cruising in remote areas as planned, need to effect a repair again for the mast or some other reason to undo rigging, I would like to know what the minimum set up of a rig is.

Thanks for any advice....... as always learning.
I do t want to sound a smartass saying Talk with a rigger, but , yes , get a rigger ...the reason is because as you say you never attempt before to tune the triple spreader stick, single and doublé spreader rigs are easy to tune and even a small diference in tensión dont make a big diference, now a triple spreader is something tricky , but is the same principle.

In any case with a rigger in place you have the chance to ask questions and see by yourself how is do it right, take notes etc... if you dont wana a rigger, i can say, the uppers get the pretensión first , if you have sweep back spreaders those make the prebend as well, D1 D2 and D3 are the last ones , dont overtight the D2 and D3 since those are bitches in making the whole process a mess, by hand until you feel tight and turning with a key útil you feel it right, if you overtight a d2 or d3 with the stick in column is easy to get everything out of tune and see a snake form later in the mast , backstay and furlers are the last ones to, in one Word with sweep back spreaders get your prebend rake with the uppers, this is the basic, later adjust the d1 d2 and d3, without sweep back spreaders uppers first and get the stick in column right, side by side , use a tape to measure from the top of the bootom togle to the bottom of the swage , screws need to start from 0 to reach a equal turning tensión , bottom screw ad swage screw, lanocote is a must in the screws... hint..

After the whole sesión, try to get a decent 15 to 20 knts and take a sail test, look at the main track at the mast and see if the mast bend weird in some place, take notes and adjust later.... Cheers.
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Old 24-08-2015, 10:36   #9
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Re: Tuning Rigging

In 40 years of sailing, i've only met two riggers who really understood tuning. They were also the only ones who insisted on sailing with me to check the tune after they were done. Unlike sailmakers, it's rare to find a rigger who does much sailing.

Here's a great guide with step by step instructions from Selden

http://www.seldenmast.com/files/1416.../595-540-E.pdf

I agree with the previous poster that your triple spreader rig is tricky. You're unlikely to find a rigger outside of 1st world sailing centers who has worked on one. You might have better luck getting advice from a good local sailmaker.

I'm sure you've already gone over the rig once, but do it again looking for any sign of crevice corrosion or fatigue. Things like slightly elongated toggle holes, turnbuckle screws with any bend, crimp fittings with cracks or rust that won't clean off, or any mis-shaped shackles. After having four spreaders fail on me over the years where they connect to the mast, I replace if there's any question.
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Old 24-08-2015, 12:03   #10
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Re: Tuning Rigging

I use a Loos gauge and tune from the bottom up. Sight up the mast track to make sure it is straight. I use my wire boom topping lift to measure that it is centered side to side (boom needs to be dropped to the deck during the entire procedure). The performance of my boat (J/27) is fairly sensitive to getting the tune right and I do it several times a summer. I find recommended tensions online and they vary by opinion. Like everything with boats, I still look for ways to do it better.
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