BoatBanter.com - rig tension gauge

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rig tension gauge

I would like to buy a rig tension gauge for wires and rods up to 12mm
(15/32"). Tho most common I found on the market are for diameters up to
5mm (3/16") with the exception of a professional device for bridges,
elevators, etc. (Portable Cable Tension Meter for cables up to 7/8")
which - of course - is great but would cost a little fortune.

Any friendly suggestion?
Daniel

rig tension gauge

ha scritto:
On Fri, 08 Feb 2008 00:41:04 -0500, Wayne.B
wrote:

On Wed, 06 Feb 2008 16:57:58 -0500, wrote:

Loos makes the best known gauges for both wire and rod rigging. Available
online, or at many chandeleries.
http://www.google.com/search?hl=en&q...ge&btnG=Search

I was going to post some links, but realized that the OP is not in the U.S. and
would get more useful links by doing his own search where he is located. This
link will at least let him see what it is he's looking for! Thanks for the
addition.

Thank you very much. I have also found few Loos retailers on this side
of the Ocean. Unfortunately I will need both rod and wire gauges and for
a couple of ranges which makes the total purchase rather expensive. The
idea is quite simple so I wonder if it would be very difficult to
construct a device myself; calibration would be an almost impossible
issue but, at least, once the tension of the rig is nearly set at a
correct value by an experienced rigger, a selfmade device could be
helpful in equalling the tensions at both side of the mast and
maintaining it in time.

The mechanical device is for sure the easiest way but... any idea why a
"twang hearing device" would not work? Maybe a piezo pick-up and an
oscilloscope? In any string instrument the change of the pitch is
strictly correlated to the tension (beside the mass/length, the
stiffness coeff., etc etc of course), isn't it?

Daniel

rig tension gauge

On Fri, 08 Feb 2008 19:18:53 +0100, Daniele Fua
wrote:

ha scritto:
On Fri, 08 Feb 2008 00:41:04 -0500, Wayne.B
wrote:

On Wed, 06 Feb 2008 16:57:58 -0500, wrote:

Loos makes the best known gauges for both wire and rod rigging. Available
online, or at many chandeleries.
http://www.google.com/search?hl=en&q...ge&btnG=Search

I was going to post some links, but realized that the OP is not in the U.S. and
would get more useful links by doing his own search where he is located. This
link will at least let him see what it is he's looking for! Thanks for the
addition.

Thank you very much. I have also found few Loos retailers on this side
of the Ocean. Unfortunately I will need both rod and wire gauges and for
a couple of ranges which makes the total purchase rather expensive. The
idea is quite simple so I wonder if it would be very difficult to
construct a device myself; calibration would be an almost impossible
issue but, at least, once the tension of the rig is nearly set at a
correct value by an experienced rigger, a selfmade device could be
helpful in equalling the tensions at both side of the mast and
maintaining it in time.

The mechanical device is for sure the easiest way but... any idea why a
"twang hearing device" would not work? Maybe a piezo pick-up and an
oscilloscope? In any string instrument the change of the pitch is
strictly correlated to the tension (beside the mass/length, the
stiffness coeff., etc etc of course), isn't it?

Daniel

Just a comment:

Are you talking about a racing boat or a cruising boat? If a class
racer then there should be some information about rig tension in some
of the class groups. If a cruiser then generally speaking the rig is
tuned by adjusting tension while under sail to make the mast stand
straight, or have the required bend.

Unfortunately, the latter description is only valid with older boats -
my own for instance has two lower and one upper shroud (each side) and
all can be adjusted at deck level. A more modern rig with upper
shrouds terminated somewhere up the mast would obviously be much more
difficult to tension properly at sea.

One point to consider is that all rig tension is ultimately fed into
the hull which is not a rigid structure, thus you actually want the
lowest tension that will keep the mast straight with no slack wires on
the leeward side. It is very possible to actually flex a hull by
tightening the shrouds too much. You quite frequently see boats with a
"hold down" strut tieing the deck to the keel to control this flexing.

I would suggest that given that a boat is not a rigid structure and
mast loading is a constantly changing number depending on sails
carried, wind, waves, ballast, etc., it is more important to adjust
the rig so that tensions on both sides are equal, rather then be
adjusted to some specific tension. In my experience (cruising only)
this can be done by simply "shaking" the shrouds to feel how tight
they are and by looking up the mast.

(Turned into quite a long comment :-)

Bruce-in-Bangkok
(Note:remove underscores
from address for reply)

rig tension gauge

Drew Dalgleish ha scritto:
On Fri, 08 Feb 2008 19:18:53 +0100, Daniele Fua
wrote:

Thank you very much. I have also found few Loos retailers on this side
of the Ocean. Unfortunately I will need both rod and wire gauges and for
a couple of ranges which makes the total purchase rather expensive. The
idea is quite simple so I wonder if it would be very difficult to
construct a device myself; calibration would be an almost impossible
issue but, at least, once the tension of the rig is nearly set at a
correct value by an experienced rigger, a selfmade device could be
helpful in equalling the tensions at both side of the mast and
maintaining it in time.

The mechanical device is for sure the easiest way but... any idea why a
"twang hearing device" would not work? Maybe a piezo pick-up and an
oscilloscope? In any string instrument the change of the pitch is
strictly correlated to the tension (beside the mass/length, the
stiffness coeff., etc etc of course), isn't it?

Daniel

Isn't the tension at both sides of the mast always equal with the mast
leaning to one sise or the other if the stays are tightened unevenly?

This is a good question that made me think. Yes, probably yes! The mast
itself is not able to give any resistance and for an obvious physical
law, in static condittions both shrouds will have equal tension.
Responding to some of you: I am referring to a classic cruiser-racer
sail boat designed by S&S in the 80' with a quite tall rig, LOA 41'. Two
orders of spreaders and only one rod vertical shroud running from the
deck to the outer part of the first spreader. Assuming that the rigger
did the right thing, from the deck I can only operate on two opposite
vertical shrouds and two opposite diagonal. I have read several things
on how to adjust the mast and have a pretty good idea; my original post
was based on the belief that a tension gauge may improve the adjustment
but you make me think that maybe this is not true.
I enjoy very much your comments and advices and thank you all.

Daniel

rig tension gauge

On Sat, 09 Feb 2008 16:32:23 +0100, Daniele Fua
wrote:

Drew Dalgleish ha scritto:
On Fri, 08 Feb 2008 19:18:53 +0100, Daniele Fua
wrote:

Thank you very much. I have also found few Loos retailers on this side
of the Ocean. Unfortunately I will need both rod and wire gauges and for
a couple of ranges which makes the total purchase rather expensive. The
idea is quite simple so I wonder if it would be very difficult to
construct a device myself; calibration would be an almost impossible
issue but, at least, once the tension of the rig is nearly set at a
correct value by an experienced rigger, a selfmade device could be
helpful in equalling the tensions at both side of the mast and
maintaining it in time.

The mechanical device is for sure the easiest way but... any idea why a
"twang hearing device" would not work? Maybe a piezo pick-up and an
oscilloscope? In any string instrument the change of the pitch is
strictly correlated to the tension (beside the mass/length, the
stiffness coeff., etc etc of course), isn't it?

Daniel

Isn't the tension at both sides of the mast always equal with the mast
leaning to one sise or the other if the stays are tightened unevenly?

This is a good question that made me think. Yes, probably yes! The mast
itself is not able to give any resistance and for an obvious physical
law, in static condittions both shrouds will have equal tension.
Responding to some of you: I am referring to a classic cruiser-racer
sail boat designed by S&S in the 80' with a quite tall rig, LOA 41'. Two
orders of spreaders and only one rod vertical shroud running from the
deck to the outer part of the first spreader. Assuming that the rigger
did the right thing, from the deck I can only operate on two opposite
vertical shrouds and two opposite diagonal. I have read several things
on how to adjust the mast and have a pretty good idea; my original post
was based on the belief that a tension gauge may improve the adjustment
but you make me think that maybe this is not true.
I enjoy very much your comments and advices and thank you all.

Daniel

The problem would be to establish what is the proper tension.

The designer would have used the hull's resistance to being heeled to
calculate the load on the rig, and thus the strength of the stays and
shrouds, but how tight? As another poster has said, you don't want the
rig too loose as the mast flopping back and forth puts undue stress on
things. On the other hand excessive tension may deform the hull to the
extent that you get stress cracks in the gel coat (actually saw this
on two catamarans rigged in Thailand.

Most authorities on tuning rigs say that (1) the mast should be
vertical; (2) the mast should be straight; and (3) the lee shrouds
should not be unduly loose. (note: I am avoiding mast fore and aft
bend).

Googling +sailboat +"rig tuning" gets some 4,000 sites on this
subject.
http://bbs.trailersailor.com/forums/...frames/read/92
for example.

I would offer one caveat though. Not all posts on the Internet are
actually authoritative. Many are made by individuals who are really
just describing "how they did it" and "how they did it" may actually
be incorrect. My suggestion is unless the procedure is described by a
known authority (Brian Toss, for example) take it with a grain of salt
and do more research to determine whether the poster actually knows
what he is talking about.

Bruce-in-Bangkok
(Note:remove underscores
from address for reply)

rig tension gauge

On Fri, 08 Feb 2008 19:18:53 +0100, Daniele Fua
wrote:

Thank you very much. I have also found few Loos retailers on this side
of the Ocean. Unfortunately I will need both rod and wire gauges and for
a couple of ranges which makes the total purchase rather expensive. The
idea is quite simple so I wonder if it would be very difficult to
construct a device myself; calibration would be an almost impossible
issue but, at least, once the tension of the rig is nearly set at a
correct value by an experienced rigger, a selfmade device could be
helpful in equalling the tensions at both side of the mast and
maintaining it in time.

The mechanical device is for sure the easiest way but... any idea why a
"twang hearing device" would not work? Maybe a piezo pick-up and an
oscilloscope? In any string instrument the change of the pitch is
strictly correlated to the tension (beside the mass/length, the
stiffness coeff., etc etc of course), isn't it?

Daniel

Isn't the tension at both sides of the mast always equal with the mast
leaning to one sise or the other if the stays are tightened unevenly?

rig tension gauge