Sizing Colligo Dux
Stretch, Creep, and Break strength.
Colligo dux is Dyneema based. Dyneema is a different material than steel so it needs to be sized differently. When sized correctly, using it for standing rigging will give you the safest standing rigging you can buy and equal or better performance than steel rigging.
Where wire is sized according to its breaking strength—taking into account a boat’s righting moment and the forces exerted on its rig, plus a safety factor—Dux is sized according to how much it stretches. Stretch is really the performance that you are looking for in standing rigging. We always size our rigging to have the same or less stretch then the steel (rod or wire) that it replaces.
The second thing we size for is a material property called creep. Creep is basically permanent elongation over time. All materials creep, some more than others. Steel has very little creep so you don’t hear people talking about it much. Colligo Dux is Dyneema based. Dyneema is really ultra high molecular weight polyethylene (UHMWP), a plastic. UHMWP has higher creep properties than steel so we have to be careful with using it for constant load applications like standing rigging. Having said that, we know what the creep properties are, we take a look at the rig loads and we size Colligo Dux accordingly. Our creep target is 0.1” of creep pre year or less. That is 1” of elongation in 10 years, Maximum. Most of the rigs we have completed actually have much less design creep than our target, as it is easy to design around. As of July of 2015 we have rigged over 750 boats without any sign of creep issues.
The third property we always look at when sizing Colligo Dux is breaking strength. When sized correctly, using the above parameters the, each shroud or stay will be 2-5 times stronger than the steel it replaces (rod or wire). A typical rig factor of safety can go from 3 or 4 to 6 or more for the same boat.
The 2 failure modes of Colligo Dux Rigging are chafe and UV damage. Both of these types of damage to the line result in visible cues, that is, the line gets fussy. You will see the damage in both cases. It’s almost like a flashing red light on the line. Keep in mind here how much stronger the line is that it needs to be. Most times you can chafe half way thru the line and still be stronger than the steel that you replaced was. UV damage will gradually make the line fuzzy, sometime in the future the line will just get too fuzzy for you and you will have to replace it. Contrast that with a swage fitting that you have no idea what is going on inside it.
When the above three parameters are completed correctly (keeping in mind that Colligo Dux Standing Rigging is fully inspectable) than it is easy to see how it can be the safest standing rigging you can buy for your boat.