Changing standing rigging - Am I being had?

My mast is currently set up with old rod standing rigging and is well past its use by date. Rather then changing to new rod I want to change to wire. The local rig shop who Ive been into a few times were suggesting once or twice over the winter that I should change the spar to a new modern factory spar and that I should buy a new rig before sails which Ive already got.

When I told them I wanted new wires I was told it could take up to 3 weeks for them to do it then when I told them the thickness for the current rods and fittings they were saying for new wire I would need to go up a size and then I would have to consider backing plates and it could be difficult to fit new terminals and backing plates into the mast where once again it was suggested that getting a new mast might be easier. My feeling on the whole thing is they just want to sell a new mast and spinning as much bull **** as possible

Do you really need to increase the thickness of the wire from the rod? I would have thought that modern wires have a strong enough breaking point that an exta milimetre is going to cause the wire to bring the rig down at the same or less breaking point then rod

 

Get a good rigger from somewhere else to examine the rigging. When you have another opinion, especially from someone who won't be selling you the parts, you will be more assured of an unbiased report.

 

We can hope they are just being careful. Unless you have the original rigging calculations you don't know what the safety factors are on each piece, neither does your rigger. So absent new calculations they will be careful and up sizes just to be safe (cover their butts) as one should always do if you want to stay in business. And switching from rod to wire can be (depending on the end fittings) a real pain.

 

Better still, learn how to calculate the forces and you can then work out roughly what you would need.
Instead of them telling (selling) you, you can tell them.

 

Dyneema Dux
Just sayin'

 

The end fittings are the same T terminals, eyes and bottle screws

 

seems like a good idea to dig up the web sites of the various wire rope manufacturers. They are likely to have some good information about the concerns and calculations that will be useful to the OP.

Failing that, consultation with a structural analyst might be worth the trouble or possible cost. from a down home perspective, the local electric utility will have a person with some skills in that area. He/she has to keep the utility poles up during hurricanes and such.

 

Are the rods terminated with a ball or a T?

 

Why change rod to wire ?

Rod is not expensive...the fittings are. If your terminals , fittings and spreader tips are still good, stay with rod.

Best not to second guess the rigger. They are the ones giving the promise of reliability.

When asking questions on BDN post a picture or a technical drawing.

Is your mast 30 meters tall or 30 ft tall ? 5 spreaders or one ?

 

Without looking at any tables, logic would suggest that a rod of a given diameter would have a higher tensile strength than a cable of the same diameter. What I would do is mic the rods and then look up the tensile strengths and then see what cable size equals the rod, my guess is you will need to upsize the diameter. The rod terminals are completely different to wire terminals so as has already been said, it would be a pain to switch.

Steve.

 

Neris, one thing you have to consider is that wire stretches a fair bit more than rod, and that is one reason to go up a size when switching to wire; this is commonly done. As long as the terminals are the same at each end as on the rod rigging, you should be able to make the switch, and I would accept the slightly larger wire over the size of the rod.

Eric