rig tension

Discussions regarding electronics, gear and other equipment of maintenance issues that ARE NOT SPECIFIC to a certain PDQ model yacht
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rig tension

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rig tension

Posted by Simon Slater on June 02, 2003 at 11:03:00:

Ah just how can the rig tensiom be measured? I really like what the Loos gauge
tell in its instructions. about 15-18% of the breaking strength, at least that
is what I recall. I believe that this would be too tight for the lowers as they
are considerably shorter and therefore are less suseptable to stretch, which by
the way is the real problem here. The lower stays problem is made worse by the
manufacturing decision to have all stays the same diameter for simplicity in
carrying spares and for dealing with issues of length at the factory during
commisioning. What that means is that the lowers are in fact much stronger than
required and far less stretchy than the same diameter cap shrouds which are far
more heavily loaded as one can imagine. This imbalance leaves one aghast when
looking at how loose the lowers need to be to allow the even bending of the
spar, like a tree that bends so evenly in a strong wind. Indeed when I tighten
these
lower stays I usually do so by hand, especially the baby stay. However I can
state categorically that there
is nothing like getting out in a decent blow and watching the mast from the mast
base, ther should be a nice gently cuve to any bending that is going, no sharp
turns or kinks

I know that this doesn't all sound very scientific, Ido hope that it is useful
though

I can help with the baby stay stuff tomorrow but right now I have to go launch
the new 36 David and I have commisioned.
regards SWS

Follow Ups:

Re: pipe diameters Simon Slater 10:34:08 06/05/03 (0)
Re: rig tension Bob Johnson 21:58:59 06/04/03 (1)
Re: rig tension Simon Slater 08:01:18 06/03/03 (0)
Re: rig tension Simon Slater 06:52:00 06/03/03 (2)

--------
Re: pipe diameters

Posted by Simon Slater on June 05, 2003 at 10:34:00:
In Reply to: Re: rig tension posted by Bob Johnson on June 04, 2003 at 21:58:00:

You Are right of course about the diameters and ther relationship to inside and
outside and wall thickness. What I was trying to say, apparently not very
clearly , is that pipe does not have the same level of tolerances on its outside
diameter as tubing does. I have found this to be true of boththe overall
diameter and consistent roundness

As such I was suggesting that one should be careful about fitting bearings

SWS

Follow Ups:

Re: rig tension

Posted by Bob Johnson on June 04, 2003 at 21:58:00:
In Reply to: Re: rig tension posted by Simon Slater on June 03, 2003 at
06:52:00:


Regarding your comments on pipe size. Although 1 1/2 inch pipe is actually
larger, the outside dia. is constant otherwise standard fittings and threading
dies could not be used.The schedule controls the wall thickness with
nos.5,10,20,40,80,160. and the inner dia. changes.The actual dia is usually
larger than the nominal until you get to 12" and above where they are identical

Tubing ODs however are identical to the nominal dimensions.

Follow Ups:

Re: rig tension

Posted by Simon Slater on June 03, 2003 at 08:01:00:
In Reply to: rig tension posted by Simon Slater on June 02, 2003 at 11:03:00:

I have been asked what does a semi permanent tensioning device look like and how
would it deploy? a very simple one would be to purchase a boom vang system with
at least a 4:1 purchase and instal one end at the base of the mast and the other
end around the shroud, if more tension is required the tail end could be reeved
backed to the cockpit winch area through the deck organinizers that generally
have a spare position. This type of arrangement would be easily used and could
be stored away when sailing

regards Simon

Follow Ups:

Re: rig tension

Posted by Simon Slater on June 03, 2003 at 06:52:00:
In Reply to: rig tension posted by Simon Slater on June 02, 2003 at 11:03:00:

Hello everyone
The launch went well and we think that the bare boat weighs about 7500 pounds
without the rig or any liquids. That is probably a savings of about 2000 pounds,
with the 50 % more sail area it should make for an interesting summer

Anyway back to the serious stuff. I have had some input from other people via
e-mail that has suggested that the reason that the lowers may end up too tight
is due to a desire to reduce the sympathetic vibrations that are established in
the spar in certain wind conditions. This is aproblem that I have experinced
myself, I corrected it by creating aspanish windlass using a length of rope and
broom handle, admittedly not terribly elegant but effective. one certainly could
arrange a more elegant semi permanent tensioning device to allow for the rig
tension requirements that I discussed in yesterdays missive

One other issue that I failed to mention yesterday is that ther is an
interesting relationship between the backstays and the capshrouds. When the
capshrouds are tightened the backstays loosen and of course vice versa, this
issue needs to be dealt with by ensuring one returns the previously tightened
stay to tigthen accordingly. This circus act may need to be repeated several
times depending how tentative one is with the wrenches. By the way lubricating
with appropriate lubricants is an absolute must to ensure that the turnbuckles
can work properly with out being damaged

As for Mr.West's problem, the issue is one of movement. The leak is caused the
chain plate is moving ever so slightly. To eliminate the leak one must tighten
the bolts to prevent movement and breaking of the seal. Thes bolts are usually
very accessable, this can be made a little more difficult if ther are optional
foot lockers installed. This is a two man job unless one is gifted with
exceptionally long arms. We have found it helpfull to remove the entire
chainplate assembly roughen both surfaces to create more friction between the
two surfaces. Installing the bolts with epoxy would also help prevent the wood
from crushing

I hope these are useful thoughts, I am not, as some of you know, very reachable
by phone, however I do regularily check e-mail through the day and will be happy
to respond

P.S. there is actualy no specific outside dianeter to the rudder shafts as they
are 1 1/2" schedule 40. What that means is these are pipes that measure the
inside diameter for use when calculating fluid movement. The outside diameter
can vary but is supposed to be aproximately 1.9" The bearings we use are custom
made for us using UHMW polyethylene plastic. We then will fit each one to ensure
a good fit.
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