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OK, thanks. I don't think that back in 1976 Pearson could manufacture a boat to that level of specification, so it would be overkill to apply those standards now. It seems to me that if the mast is "in column" at the slip, then it would have to be the same when sailing (even though that column is at an angle) and that the looseness of the shrouds comes only from hull flex, which would not necessitate adjustment to the shroud tension as that would take the mast "out of column" when the stresses are removed. What an opportunity for some circular reasoning!
As to tension, a gauge would be useful to insure that one is not over tightening the shrouds and stays for reasons noted above, but certainly not to "tune" every wire to a specific number. Kind of like building a bicycle wheel.
John
 

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. It seems to me that if the mast is "in column" at the slip, then it would have to be the same when sailing (even though that column is at an angle) and that the looseness of the shrouds comes only from hull flex, which would not necessitate adjustment to the shroud tension as that would take the mast "out of column" when the stresses are removed.
John
Not at all. Systems are only static while they are in fact static. We tend to think of masts and rigging as being static because in normal conditions it is a little odd to think of steel and aluminum stretching. But under the loads expected and the length involved there is a substantial amount of stretch that is expected.

Just a quick run thru the numbers using a Pearson 28 as an example. The upper shrouds are 1/4" 1x19 wire 38' 6.5" long. The tuning guide indicates 700lbs on the upper shrouds.

The in/in/1000lbs stretch for 3/16" 1x19 wire is 0.0013059.

So the length in inches is 38*12=456+6.5= 462.5"

Just from the static load expected then the wire has already stretched...

462.5 * (700/1000) * 0.0013059 = .422 inches.
 

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Do not expect things to remain exactly the same under sail, as they are at the dock. There are no loads on the rigging at the dock, and things do move and bend.

You don't need to sight up all the way from the base of the mast. Plant your cheek on the sail track above the boom, and sight the masthead.

If the mast tip is falling to leeward, this is bad. The upper shrouds need to be adjusted.
If the center of the mast is falling off to leeward, the lower shrouds need to be adjusted.

You could also try a laser pointer sighted along the track, pointed at the masthead. I imagine that you'd have to try that early in the morning, or in the evening, when ambient light is lower.
 
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