Converting to and Fabricating Bronze Chainplates/Tangs

[Jack]

There is a number of things to consider. Dynex does not need to be tensioned to 15%. In fact you do not size Dynex Dux that way. You size it to eliminate creep and stretch. It is so strong you do not use the same set up.....sorta

Here is an example: Westsail 32 Formerly had 1/4" and 5/16" SS wire. Brion says to never load a shroud more than 10% of it's breaking strength and a headstay/backstay more than 15%. If I recall 20% is the ultimate maximum on any wire.

1/4" wire is 6,900 lbs
5/16" wire is 10,600 Lbs.

The maximum tension on your stays should never exceed 1590 lbs. (15% of 10,600)

This would be the same tension you put on a Dynex Dux rig....those numbers.

This is the number we use to determine what size Dux rope to replace the wire. Our rule is keep the static load or tension under 15% of the breaking load of the rope, and you will eliminate creep and stretch. In fact it stretches less than wire, when sized properly.

We used 9mm Dux on the Westsail. Breaking strength 26,500 lbs. If the Westsail is tensioned to 1k or so (in reality) We have a huge margin before we ever reach the 15% point.

15% of 9mm Dynex Dux is 3,975!

By replacing the rig with rope that is more than two times as strong, we have gained a huge leap in overall strength, and have no stretch or creep. The rig uses the same tension numbers as with wire.

You are right, if we were to tension it to the 15% of the ropes strength, we would pull the mast right trough the bottom, or some other nasty thing.

I uploaded a bunch of photos of the boat on the URL below. Enjoy!