Synthetic shrouds on a 3 spreader rig?

[Gashmore]

make sure you run some numbers on the loads involved and do not just take the sizes of the original wires

I have just spent the weekend with Mssrs. Larsson and Eliasson and it is easy to see how the original rod specs were calculated. For example the tension on V3/D4 comes out 4,100 lb. According to L&E for the top diagonal the design load is 2.8 times the tension or 11,480lb. D4 was spec'ed as -12 so I am pretty confident of that 4,100lb. The choices of all the other rod works out similarly. When it comes to selecting Dynex I think I just work with the tension and use a 5:1 factor to stay under 20% of breaking strength. In this case 9mm. Does that sound right? If so 11mm will handle everything below that.

Actually selecting Dynex is a lot simpler than optimizing rod. Rod would take 6 different sizes to minimize weight. With Dynex there are only two in the ranges I need. Makes for more windage but the weight up saving is amazing. Also I can make up a Brummel in a few minutes. I have to drive to Charleston to get a rod headed. :-)

[Joe Henderson]

Dear Gashmore,

You have a handle on the problem.

9 and 11 mm sound about right - as does the 5:1 safety factor.

You must pardon the pun, but you have hit the nail on the head when you talk about ease of modification etc. This I think will be the greatest boon and, paradoxically, the greatest threat, to the wider acceptance of fibre rigging.

With something so easy to access there will inevitably be the rash of bad and unsucessful projects until it becomes comonplace and accepted my the masses.

There will of course be the usual amount of litigation and argument when the first high profile rig comes down and hurts someone, but we will have to guard against that eventuality with competent workmanship and the education of our customers.

Regards,
Joe Henderson.