Tensioning Dynex rig

[seacap]

Hi all,
I have had a rig built with Dynex Dux for the last 4 years. One of the questions has always been how tight to set it up.
I did as I have always done. Taken the boat out sailing and tension until the shrouds no longer goes slack on the leeward side.
I now see that Colligo Marine has issued a modified guide for using the Loos PT-3 gauge. On the chart for 7mm they list 6 on the gauge as being equal to a 650lb load. My rig is tight, no slack on the leeward sailing side. But it measures only 2 on the Loos gauge.
Is this because of the stretch of the Dynex being lower than wire? I'm I just not tight enough? Why would I want to be tighter? Mast appears to stay in column.

Inquiring minds want to know.
TA
Gary

[Brion Toss]

Hi,
First, are you sailing in typical max loading conditions? The leeward shrouds won't go slack, even with a relatively slack rig, if you aren't loading the rig up. The typical max will vary with your location, so you'd tune tighter, for higher average windspeeds, in San Francisco, versus San Diego, for instance.
Next, what is the strength of that 7mm relative to the vessel's righting moment? If it is on the large side, you won't need as much tension to keep the leeward shrouds from getting floppy.
Finally, yes, Dux is less elastic than wire, at least when it is sized correctly. but it still wants tuning.
Hoping that John Franta will chime in here, too.
Fair leads,
Brion Toss

[jfranta]

Hi Gary, yes as Brion says it depends on the conditions you are in, but in general you want the leeward shrouds to just start loosening at your reef point with full sail (however you define it) As far as the dux goes, the only issue you need to worry about is creep, we base that on pretension, since creep is a time based phenomena. Your rig will see the pretension load for most of its life, depending on how much you sail. (Sadly most boats are above 95% of the time with pretension as the rig load). Our creep target is 0.1" per year or less (1' in 10 years). For a 50 foot shroud in 9 mm that is about 1200 lbs constant tension. For a 50 foot shroud in 7 mm that is about 700 lbs constant tension. So use that as a reference, interpolating or extrapolating for length as needed and keep the loads below the limit and you will have no creep issues. My Guess is for your boat you will have no issues staying below 700 lbs on your 7 mm line and you could proably tolerate more as I am sure your length is shorter than 50 ft. If you want to send me your exact lengths I can do the calculations and get you an exact number.

Caution: if you are one of the few who really spend alot of time sailing then dynamic loads need to be figured in to the creep equation.

Hope that helps.

John Franta, Colligo Marine.

[seacap]

Solid information gentlemen. Thank you for the replies.