Mast Rigging Tensions

Concerto

Concerto

.
May 9, 2013
55
Catalina 310 Oyster Bay, NY
When the mast was pulled and stepped for maintenance this summer, the yard told me they "dock tuned" the rigging. My Loos PT-2 gauge shows many different tensions on each set of 1/4" shrouds. Has anyone tuned their rigging and if so, would you please tell me the proper tensions for the aft lowers, forward lowers, intermediates, uppers and split backstay. The uppers are 9/32 and don't fit in the PT-2 device. I will be buying a PT-3 as soon as I know the proper tension for the uppers and that will take care of both sizes.

As always, I thank you for your responses and advice.
Alan, Concerto in Sea, #189
 
BC Bernie

BC Bernie

.
Aug 29, 2016
131
Catalina 2004 310 (Hull #250) BC
Hey Alan,
Jesse has written a great blog on rig tensions on this forum and his Smitty blog. I’ve been talking to pro riggers and many of them are using the Spinlock Rig-Sense gauge now in place of the Loos gauge; I’m getting this as I’m about to change out those Garhauer turnbuckles with some nice Blue wave ones.

Good luck!
 
shemandr

shemandr

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Jan 1, 2006
7,068
Slickcraft 26 Sailfish
The tension is more or less a function of the wire diameter. Usually 20% or 25% of yield strength. These numbers are readily available from wire manufacturers. There is a difference in terminology in failure strengths and I'm not an engineer. So don't kill me on "Yield" vs. other definitions of failure. The wire manufacturers show the working loads - use what they give you. It is incorrect to think you tune the rig by changing standing rig tensions. The reason tuning guides focus on measuring lengths is that is how you tune the rig.
Oh yeah, and a "Dock Tune" means the mast was still standing when the workers left the boat.
 
jviss

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
shemandr said:
It is incorrect to think you tune the rig by changing standing rig tensions.
Click to expand
That is certainly not true, to my knowledge. There are lots of books on this topic; I hav a couple. You can certainly change the shape of the mast and its behavior with shroud and stay tension, especially stay tension. Hence, the backstay tensioner.
 
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Will Gilmore

Will Gilmore

.
Oct 19, 2017
7,744
O'Day 19 Littleton, NH
I would take "dock tuned" to mean they have centered and plumbed or raked everything as recommended and tensioned the rig to a minimum starting point. The next step is to take her sailing and watch for movement, forestay sag, lose and dancing turnbuckles when reaching. Be sure to take up slack and tighten symmetrically. Don't over bend or allow spreaders to drop below horizontal or keep just above horizontal, depending upon the standards for your rig. Keep the mast inline, no 'S' curves. Natural symmetry, proper rake and bend and no loosening of the lee shrouds in 20 knot winds on a beam reach.

-Will (Dragonfly)



-Will (Dragonfly)
 
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JK_Boston_Catalina310

JK_Boston_Catalina310

.
Nov 18, 2010
2,441
Catalina 310 Hingham, MA
Will Gilmore said:
I would take "dock tuned" to mean they have centered and plumbed or raked everything as recommended and tensioned the rig to a minimum starting point.
Click to expand
I take it a step further. I use the halyard to tension the rig by tying it to a cleat on the dock an cranking until I have a good heal. Then you can check the tensions again in a more controlled manner. When I do it this way I have never found the tune to be off when I go sailing. At anchor or on mooring I have had to get a little more creative and either connect to another mooring or put out an anchor on the beam of the boat.

Fair winds,

Jesse
 
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JK_Boston_Catalina310

JK_Boston_Catalina310

.
Nov 18, 2010
2,441
Catalina 310 Hingham, MA
BC Bernie said:
Hey Alan,
Jesse has written a great blog on rig tensions on this forum and his Smitty blog. I’ve been talking to pro riggers and many of them are using the Spinlock Rig-Sense gauge now in place of the Loos gauge; I’m getting this as I’m about to change out those Garhauer turnbuckles with some nice Blue wave ones.

Good luck!
Click to expand
@Concerto

Here is the article BC mentioned.

Good luck and fair winds,

Jesse
 
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Tom J

Tom J

.
Sep 30, 2008
2,304
Catalina 310 Quincy, MA
shemandr said:
The tension is more or less a function of the wire diameter. Usually 20% or 25% of yield strength. These numbers are readily available from wire manufacturers. There is a difference in terminology in failure strengths and I'm not an engineer. So don't kill me on "Yield" vs. other definitions of failure. The wire manufacturers show the working loads - use what they give you. It is incorrect to think you tune the rig by changing standing rig tensions. The reason tuning guides focus on measuring lengths is that is how you tune the rig.
Oh yeah, and a "Dock Tune" means the mast was still standing when the workers left the boat.
Click to expand
This goes against everything that Catalina says in the owner's manual supplied with the boat. You must first eyeball the mast for plumb and straightness, adjusting the stays and shrouds as needed. The rest of the tuning goes along with what Jesse described.
 
shemandr

shemandr

.
Jan 1, 2006
7,068
Slickcraft 26 Sailfish
I think eyeballing a rig is extremely difficult to do accurately. I'm not sure what the Catalina tuning guide says because I've never read it. My point is that use a tape measure to center the rig by comparing lengths of shrouds. I mis-spoke about adjusting turnbuckles. You do adjust them, but not to increase tension on the shroud at this stage. It is make pt. and st. lengths the same. Done also with lowers and the mast is centered. Then you adjust the tension on the shrouds by tightening one side and then the other with the same # of turns. The tension you will stop at is in that range of the working load of that diameter of wire. I believe those numbers are right there on the Loos gauge. Put another way the tension in a shroud is a function of the diameter of the wire not the position of the mast.
I
 
JK_Boston_Catalina310

JK_Boston_Catalina310

.
Nov 18, 2010
2,441
Catalina 310 Hingham, MA
shemandr said:
The tension is more or less a function of the wire diameter. Usually 20% or 25% of yield strength.
Click to expand
Wow. Didn't realize you said numbers this high until Tom commented. The Loos Gauge numbers are around 15% of breaking strength for forestays and 10% for shrouds.
 
jviss

jviss

.
Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
Yield strength is incorrect. Rigging tension is always specified in terms of % breaking strength.

(The yield point is that point where elastic deformation ends and plastic deformation begins.)
 
shemandr

shemandr

.
Jan 1, 2006
7,068
Slickcraft 26 Sailfish
This is why I didn't want to get into the details of physical properties of wire. Whatever the parameter, it is still a function of wire diameter. :banghead:
 
jviss

jviss

.
Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
shemandr said:
This is why I didn't want to get into the details of physical properties of wire. Whatever the parameter, it is still a function of wire diameter. :banghead:
Click to expand
YOU are the one who said "yield strength!"
 
shemandr

shemandr

.
Jan 1, 2006
7,068
Slickcraft 26 Sailfish
I also said " There is a difference in terminology in failure strengths and I'm not an engineer. So don't kill me on "Yield" vs. other definitions of failure." None of which change my Rx of tuning technique based on measurement.
 
BC Bernie

BC Bernie

.
Aug 29, 2016
131
Catalina 2004 310 (Hull #250) BC
Finally got around to replacing those 8 IMG_3362.JPGIMG_3361.JPGIMG_3363.JPGIMG_3367.JPGGarhauer turnbuckles with some 1/2" Bluewave ones. A flat $10 pry bar fits perfectly into the slot. Pre measured using Spinlock Rig Sense for rig tension, and callipers for shroud inter stud distance, then verified settings duplication post switch up. Next up: tuning.
 
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JK_Boston_Catalina310

JK_Boston_Catalina310

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Nov 18, 2010
2,441
Catalina 310 Hingham, MA
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