Generally the rule is 15% of the breaking strength of the wire for the upper
shrouds and fore and backstays. 10% of breaking strength for the lower.
That gets you started with the mast in column. Then tune the rest of the
way under sail.

On Sat, Apr 17, 2010 at 11:47 AM, Jubilee <> wrote:

Jubilee is getting her mast re-stepped after 1 1/2 years out of the water.
Does anyone know what the proper tension is for the cutter rig?

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John Stevenson
http://www.svsarah.com
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There were at least two rig heights of the cutter made, so tension would be
different for both. There are gizmos out there to measure rig tension, but
I’ve never really bothered with one. They are made mostly for small boats
anyway.

Like most folks, I tune the rig by sailing the boat and adjusting as
necessary. When on a tack, the leeward shrouds should be loose, but not
flapping around. The uppers should be tighter than the lowers and should be
adjusted to put the mast straight and even. Resist the temptation to
tighten the leeward shrouds when under sail. You can screw stuff up this
way. Take the boat out for a sail and see how she feels. If the shrouds
look loose and you don’t point well, take her back to the dock or mooring
and tighten the shrouds a couple of turns.

I use a shroud touched to the toe-rail to measure the relative adjustment of
the uppers. I look up the back of the mast track to get the lowers even.
There is no adjustment for the forestay, and I adjust the backstay with a
hydraulic tensioner to as little as 500 lbs when running and 3500 lbs when
pointing, more or less depending on how strong the wind is. You can’t get
more than about 2000 lbs with turnbuckles without galling the threads. I
put a little WD-40 on the threads when tuning. Yes, its not a very good
lubricant, but you don’t want a good lubricant there anyway. Its just
something to make the job easier and disperses after a few days.

Rich

I did a bit of research into this last year for Silver Heels. Got some good
advice and information leads from this group. I have eyeballed my rig tuning
on previous boats for decades. Never realized how far off I probably was,
which at least goes to show that the mast will probably stay up even if you
do screw up the rigging tension. Finally broke down and bought a Loos
Tension Gauge last fall, the Model PT Series for wire sizes 1/4″ to 3/8″,
which covers all the rigging wire sizes on my boat (since I upsized the
mizzen wires to 1/4″). As I recall the gauge cost a couple of hundred bucks,
but I consider it money well spent. I can keep my rig perfectly tuned
forever, and help others with theirs. The instructions and wire tension
guide are online at
http://www.loosnaples.com/how-to-use-pt-series-tension-gauges-pg-12.html

Anyway, between the group feedback, a few articles I read, and the Loos
instructions this is what I came up with:

General Wire Tension Rule:
Upper shrouds, head stay, back stay – tightened to 15% of working strength
Lower shrouds – 10% of working strength

11/30/09 – Tuned Silver Heels’ standing rigging with Loos Tension Gauge as
follows:

Main uppers = 15%
Main lowers = 12%
Staysail stay = 13%
Mizzen uppers = 15%
Mizzen lowers – 12%

Longer wires will stretch more, so they need to be set up tighter than
shorter wires.

Flattening the mainsail will help the boat sail more upright in strong
winds. Bending the mast a little helps flatten the mainsail.

1) Backstay(s) should be tightened to 20% of breaking strength. Induce a
little bend in the mast (less than one mast depth) with the backstay, then
take up on the lowers “to control and define the bend.” Sight mast.

2) Uppers tightened to 15%. Sight mast.

3) Lower shrouds tightened to 10%. Sight mast.

4) Staysail stay tightened to 12% (I made this up). Sight mast.

Then go sailing. First just sail around in a stiff breeze to get out the
initial stretch in the wire. Then check that the leeward shrouds aren’t
floppy while sailing to windward. If they are, tighten them a little, “until
you feel a slight increase of resistance in the (well-lubricated)
turnbuckle.” Then tack and repeat on the other side. Then sight up the mast.
If the head falls off to leeward, the uppers may be too loose, or the lowers
too tight. Try the lowers first.

If the headstay sags too much, tighten up the backstay.

Bottom Line: Keep the stick laterally straight, with little bend aft, and no
slack in the wires.

Finally, cotter-pin all the turnbuckle studs.

Or just hire a rigger.

And remember to always…

Reef early,

Tor
~~~~~~~~~~~~~~~~~~~~~~~
Silver Heels, P-424 #17
http://www.SilverHeels.us
~~~~~~~~~~~~~~~~~~

The new Loos gauges almost justify the price by allowing you to monitor the
tension while making adjustments to the turnbuckles. I’m glad I bit the
bullet 5 years ago and purchased one.

On Sun, Apr 25, 2010 at 7:59 PM, Jubilee <> wrote:

thanks for all the information. We were looking at the Loos and was
wondering if it was going to be worth the outlay of funds. I’m more apt to
buy it now. thanks

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Regards,
John Stevenson
http://www.svsarah.com
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