Maybe both ? Different companies different publized specs ?

Surely there is more then one company in the world make steel wires ?

However, I've written most of my post from memory, I haven't done a detailed check-up on the facts. Although I'm pretty sure about most specs used in the posting.





Good question, How would anyone go about that ?

Such a calculation would require a much more elaborate model and in depth knowlegde of the causes of such shock loads like wind gusts, sea-state and sailor behaviour. And even then it can only be made to work after making a whole lot of assumptions. Such a model will easily take 1000's of hours in research and implementation. Even when using some of the modern software simulation packages. These packages make creating pictures and nice looking graphs easy, but they do not do the modelling for you or finding all the parameters for the variables involved in such an elaborate model.

Basically this is the reason why engineers use safety margins so much. And it is the prime reason I don't want to skim on these. I made a static calculation assuming perfectly stable conditions and flat water. The result was that the forestay would see 571 kg (rounded off to 600 kg) tension already under these conditions. A 720 3mm 1x19 wire only had some 26 % safety margin on that. Apparently 2.5 mm dyform has less then that. I felt that considering the "perfect" nature of my model that that was too little. So I went for 1235 kg for 4 mm 1x19 with a safety margin of 116%. A little bit too much but it was the only alternative I could find. No-one could sell me 3.5 mm 1x19 or 3 mm dyform, both of them would have better.

Wouter