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  #31  
Old 01-23-2012
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Most insurance carriers now (in the fine print of most of their policies and 'renewals') require rig changeout every ~ten years ... even if the rigging is stored in a box and not used, etc. Or if damage occurs because of rig failure and the rigging wasnt replaced in that time frame ... casualty loss not covered!

You better have previous receipts to prove this if you do have a failure or casualty loss, etc. One really has to actually read the fine print of your policy.
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  #32  
Old 01-23-2012
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Quote:
Originally Posted by DougSabbag View Post
What constitues this: "If the standing rigging is toggled correctly.." ?

The toggle acts like a universal joint

The best example is roller furling as IF toggles are not installed on deck and at the masthead the stay will break pretty fast
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  #33  
Old 01-23-2012
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Quote:
Originally Posted by RichH View Post
I dynamically tune my boats ... but I have a healthy dose of material science, metallurgy, engineering, amateur sailmaking, etc. background; so my reasons may be quite different from anyone else.

I dynamically tune for the following reasons:
1. first and foremost - sail shape ... if the forestay tension (improper sag when windloaded) doesnt precisely match the leading edge shape of the sail as cut/designed, then I readjust (while underway) to get it 'close'.
2. Most rigging is stainless steel and that presents a special problem all by the very nature of 300 series stainless --- vulnerability to fatigue failure. Fatigue is vastly accelerated any time 300 series stainless is cyclically loaded beyond ~30,000 psi (even that the material has a ~90000 psi 'ultimate tensile strength' ... but that applies only to 'ductile failure' & non repetitive load conditions). The all important material characteristic for 'boat rigging' and plates, etc, I adhere to, is that I expect that the material/rigging WILL catastrophically fail when there are more than (estimated) 1 million 'cycles' (about 1 circumnavigation) where the component goes beyond 30K psi. Keep that loading UNDER 30K psi (30% of rig tension, etc.) and the part 'can' last virtually 'forever' (theoretically from a materials science or metallurgical point of view).

So, I do use a tension gage the rigging while getting the boat over 'towards' a 45° heel angle ... as after the 45° heel angle the loads diminish due to 'trigonometry'. If I cant get the boat to 45° I simply measure what I have at the max. angle and then calculate what the loads would be @ 45° over, etc. ... and then assuming that my rig has an appropriate inbuilt design safety factor (probably at least 3X+ for a "perry-boat") I arrive at the max. tension and then reduce the 'static' tensions as needed and still to get the needed mast 'pre-bends', forestay 'shape', etc.
When Im sailing 'hard', I simply dont want any part of the rig tension to (much) 'go over' 30% UTS ... and will apply 'helpers' (runners, etc.) to get what I want ... (hopefully) less than 30% UTS at 'max'. conditions.
When 'sailing' I monitor the backstay tension (gage attached) and if that backstay is going much over 30%, I then reduce/reef of change a sail, head off, etc. etc.
(FWIW I sail a Taiwanese made Ty37 and the Formosans are long noted for their lack of metallurgy expertise ... and I claim so too many 'riggers' also fit in this category but 'graciously understand' and 'accept' this .... as I dont want my cost of maintenance exceeding the cost of the national debt of the USA.).

I didnt do this when I was actively racing my 'sport boat' (dynamic on-the-fly mast raking and 'very' bendable mast, independent forestay tension, etc. and over-design Safety Factor of 1.5X) and did lose a few masts, rigs, etc. overboard - all due to 'catastrophic' fatigue failure.

Thats my 'impression' of dynamic tuning ... for sail 'shaping' and for keeping the rig up without undue fatigue failure 'surprises'.

Ultimately one has to consider that since there ARE noted rig failures, increasingly insurance underwriters demanding (panic, seemingly) a total rigging changeout every 10 years, etc. ... that the 'inherent design and selection' of the these materials ... is quite 'faulty' ... and 'someone' is erroneously designing rigging etc. in accordance to 'ductile' values and not 'fatigue endurance' values. Cant be otherwise.
WOW!!!! now that IS impressive.

May I ask some questions?

1. When healed over at 45 degrees, are you checking and adjusting the windward or down wind shrouds / stays?

2. Using a Gulfstar 50 as an example, I usually had about 65 lbs of tension on my shrouds / stays. If that is the setting / reading, at the dock, what am I shooting for, i.e., how many lbs. of tension, while under way, while "dynamically tuning"?

3. How would I determine what the "30% UTS" / ultimate tensile strength of the cables to be, related to lbs of tension as read from a guage?

THANK YOU for your very detailed information!!!
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  #34  
Old 01-23-2012
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Quote:
Originally Posted by tommays View Post
The toggle acts like a universal joint

The best example is roller furling as IF toggles are not installed on deck and at the masthead the stay will break pretty fast
Hmmmmmm, I am wondering if ALL boats have these toggles installed?

When I stepped the main, I clearly remember that all there was at the masthead were bent flat flanges, with holes where a pin went through, and went through an eyelet which the cables were affixed to.

I don't remember any special "universal" like joint at the cable to chainplate connection either. More along the lines of a bolt and a nut, with a locking pin.
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  #35  
Old 01-23-2012
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Quote:
Originally Posted by casey1999 View Post
I am also concerned with my rig and truly only feel confident in it after I do the inspection and tune it myself. I purchased a Loos rig tension gage (model PT3-M) so I could determine the tenstion of all shrouds and stays. The tension gage can be used while under sail, so it will give me real time rig tensions.

The instructions that came with the gage say you should tension the rig at the dock (several tension values are given depending on your rig). Then you take the boat for a sail in a stiff wind and basically tune the rig so that the lee shrouds do not go slack (dynamic tune?). As long as there is no slop in your rig including mast pumping, and the tensions are close to what is considered typical, rig should be considered well tuned (assuming rake and mast bend are acceptable).
Casey.... this was what I did not do after the main mast stepping 10 months prior to my rig "failure":
"Then you take the boat for a sail in a stiff wind and basically tune the rig so that the lee shrouds do not go slack..."

Assuming that the lee (downwind) shrouds / stays do go slack, and you adjust those to be, oh lets say 65 lbs of tension, then wouldn't the mast be bent toward that recently adjusted side when you come about?

Or how do you do this dynamic tuning, without pulling the mast to one side or the other, if you're adjusting it while she is heeled over?

Please pardon my ignorance, but what the hell, I am ignorant. :-)
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  #36  
Old 01-23-2012
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Quote:
Originally Posted by Sailormon6 View Post
What about backstay adjusters? When you round the weather mark and ease a backstay adjuster, or, when you start to become overpowered on a windward leg and you increase the tension on the backstay adjuster, bending the mast on a fractional rig, or reducing headstay sag on a masthead rigged boat, doesn't that make a radical change in rig tuning on the fly? It seems to me that using a backstay adjuster is the essence of dynamic rig-tuning.
You're right "using a backstay adjuster is the essence of dynamic rig-tuning", but Pythagoras' rule comes into play; tighten the backstay, the forestay lengthens (or rather the distance between the top of the mast and the furler gets longer). Furthermore, that's why the shrouds should be toggled (and that they're functional, not seized). You're better off being a bit sloppy than overtightened.
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  #38  
Old 01-23-2012
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"Casey.... this was what I did not do after the main mast stepping 10 months prior to my rig "failure":
"Then you take the boat for a sail in a stiff wind and basically tune the rig so that the lee shrouds do not go slack..."

Assuming that the lee (downwind) shrouds / stays do go slack, and you adjust those to be, oh lets say 65 lbs of tension, then wouldn't the mast be bent toward that recently adjusted side when you come about?

Or how do you do this dynamic tuning, without pulling the mast to one side or the other, if you're adjusting it while she is heeled over?

Please pardon my ignorance, but what the hell, I am ignorant. :-)"



Take half of the slack from lee shrouds, tack and tension the new lee shrouds as much as the old ones.
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  #39  
Old 01-23-2012
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Dynamic tuning – Yes you need to make sure both sides have equal tension. If not, your mast will no longer be in column (not good!) and, you will be slower on one tack than the other. I use my Loos gauge to check for equal tension. You can do this without a gauge by counting the number of new turns you are putting on the turnbuckle and doing the same to the other side after you tack. Properly tuned, your wire shouldn’t stretch for a very long time so dynamic tuning is something done very infrequently like after a re-wiring. I actually have two sets of tune, one for light days and the other for our (normal) heavy air days. A boat tuned for heavy air will be a little too stiff and not perform as well on light days. Probably more important for the racer types than the cruisers. On a mast head rigged boat, the backstay adjuster pulls out the stretch in the headstay, stiffening up the boat and causing it to heel less. Next time you are sailing in heavy air site your headstay along the mast. If you see it bowing out to leeward, chances are you need to tighten headstay tension or would benefit from a backstay adjuster. On fractional rigged boats, you are pulling a curve into the mast using the headstay as a fulcrum. This reshapes the main.
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  #40  
Old 01-23-2012
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Quote:
Originally Posted by DougSabbag View Post
WOW!!!! now that IS impressive.

May I ask some questions?

1. When healed over at 45 degrees, are you checking and adjusting the windward or down wind shrouds / stays?

2. Using a Gulfstar 50 as an example, I usually had about 65 lbs of tension on my shrouds / stays. If that is the setting / reading, at the dock, what am I shooting for, i.e., how many lbs. of tension, while under way, while "dynamically tuning"?

3. How would I determine what the "30% UTS" / ultimate tensile strength of the cables to be, related to lbs of tension as read from a guage?

THANK YOU for your very detailed information!!!
Many designers (seem, to me) to use the 45° heeled angle as the maximum 'normal' developed stress vector in the caps shrouds ... and then add the appropriate safety factor (multiplier) to that value and then seemingly choose the 'next large' wire diameter to bear that stress. at least thats how I 'back-calculate' when Im 'trying to 'get inside their heads' and WHY did they select this or that, etc. (For example, a 'blue water' design with FS=3 will only be using '1/3' of the load bearing capability of the wire when the boat is over at 45° ... meaning you have 2/3 of the that ability in 'reserve' to handle 'unforseen and unpredicted' loadings ... and stunningly most 'well designed' boats seem to always back-calculate that 45° angle yielding *slightly less than that 30% UTS* ... and 30% UTS is the 'go-by' of *fatigue endurance value*. This may be entirely wrong in how the designers actually do this but this is what I see when I 'back-calculate', for 'fun'.

You Gulfst'r is probably going to have 3/8"Ø cap shrouds ..... with 14,800 lb. UTS. 30% of 14.8K = 4,400 lb.; 15% = 2,200 lb. 65#/.110 sq. in (cross sectional area of 3/8"Ø.) = 588 lb. ( = 4% UTS of 3/8 wire).

A Loos, etc. gage will have a 'size index' in the margin of the gage to determine wire diameter .... just use the scale that corresponds to the diameter and read in %.

;-)

Last edited by RichH; 01-23-2012 at 05:47 PM.
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