Re: Rigging Tension

BCC Forum
1

I agree with Eric (and Rod) on the value of the empirical approach as
an alternative to “doing it by the numbers”. Whether setting up a
cruiser or a racing dinghy, after getting the mast in column and
“straight in the boat” I think the main variables are first the degree
of rake and after that the amount of headstay sag. Since the BCC has
a non-bendy mast a lot of other adjustments are probably not so
relevant. I recall some earlier postings in the archives about
weather helm sometimes being an issue with the BCC so perhaps mast
rake is worth special attention. Anyone with more BCC experience than
I have an opinion on that?

Scott
(S/V Itchen BCC #73)

PS. Right now Itchen is moored in Black Sound, Green Turtle Cay and
Dottie and I will be cruising the Abacos and maybe the Exumas until
the end of June or thereabouts. Any other BCCs in the area, or advice
on nice out-of-theway gunkholes to visit?

S.

On 5/14/05, BCC Forums bccforums@samlmorse.com wrote:

Author: epomber
Username: epomber
Subject: Re: Rigging Tension
Forum: BCC Forum
Link: http://www.samlmorse.com/forum/read.php?5,4041,4044#msg-4044

Hello Rod, I have been following the BCC forum for the last three years
while building by BCC. It is a great source of information and inspiration
when the hours get long. I have been racing one designs for 35 years and
have not found two loos gauges that read the same. We have always used a
deflection test to calibrate our gauges and use them as a relative indicator
for set up only. When we have checked them with a strain gauge they were all
inaccurate. The way I have always tensioned a rig on a cruising boat is to
snug the rig up and make sure that it is in the middle of the boat. Then go
for a sail and load the rig up and make sure that the spar is in column. If
not make the necessary adjustments (with the pressure off) without getting
things to tight. As soon as you go on the wind and the leeward shrouds go
slack how tight and strait things were at the dock doesn’t matter. Head stay
tension is more a matter of matching the luff curve on the jib than the
numbers on a gauge. Of course this is just my opinion on the simple
approach.

Eric Pomber
----- Original Message -----
From: “BCC Forums” bccforums@samlmorse.com
To: bccforum@samlmorse.com
Sent: Saturday, May 14, 2005 6:40 AM
Subject: Rigging Tension

Author: IDUNA
Username: IDUNA
Subject: Rigging Tension
Forum: BCC Forum
Link: http://www.samlmorse.com/forum/read.php?5,4041,4041#msg-4041

Rigging tension seems to be more of a guess than engineering. The
guidelines I use are the mast should not deflect to either side nor pump
under load but do not have a good sense of when the rig tension is too
loose
or too tight. I was wondering if someone could suggest a starting point
for
setting the rig tension loading in pounds for the shrouds.

Fair Winds,

Rod

–
Scott

2

Scott:

 To expand on my previous post re: rig tuning and weather helm.  With a full batten Elliot-Pattison mainsail, I had pretty significant weather helm at the suggested 4-5" of aft rake in the mast.  The main has more roach and the boat is much happier at O" rake.
 After using the Loos to set final tensions I found that my "subjective" sense of tight was a little soft for the head/back stays and the cap stays.  I do think it is important to match stay tensions side to side once you have the mast "eyeball" true.  I don't know anyone with a hand calibrated well enough to replicate tensions stay to stay so the less expensive Loos gauge will do that with sufficient relative accuracy.
Just launched Saturday and am watching the 45 degree rain clouds roll in...sure wish I was where you are.

                                   Tom