Rigging experts

[idlerboat 116]

.....measuring rigging stretch is a reasonable way of checking tension....

you can find a wire size to stretch tables on the internet.

The actual measured distance matters only as a fraction of the calculation. (and the longer the distance the more accurate)

Otherwise use  a Lews guage.. (loos) ..

They are not hard to make if you want. 

Snatch loads on rigging is bad ! ( slack tension) BUT..there is a surprising amount of boats that when you start to get the tension up properly the boats beam decreases and the freeboard increases.....!!

Older timber boats need to be treated with caution. This means they are more prone to serious rigging failure because the rigging cant be pulled up enough to reduce snatch loads...

The greatest load is on the lowers first then D2s, then caps in a two spreader rig. (That is why the wire size on the lowers is traditionally larger than the caps.)

In a swept back spreader rig with discontinuous stays and aft only lowers, the balance is between those and the fore stay and inner stay (baby stay) if you have one,

The back stay does very little. Increasing the tension on the backstay (adjustable backstays) is more about mast bend to create a different sail shape.

The rig should be set so that there is a reasonable but not excessive tension on the forestay. (without large backstay tension).

Remember that hanging a furler with foil windage etc is heavy...dont expect a rod straight bar up front. 

Keep the mast in reasonable column when setting it up (sight up the sail track) . Use a plumb bob on a still day to set aft rake ( no aft tension ) to your rigging plans. Check mast set athwart with a tape from the lower spreaders to the chain plates for evenness. (trusting that your boat was a miracle build and perfectly symmetrical )

With very light tapered mast sections and heavy furlers it can be tricky...just make sure that you have the right mast rake and the right length on your forestay before you start !!

It is common for people to get it wrong....they get tension on the furler, but the whole mast ends up like an S or a banana (and they dont notice it) . ((remember site up the sail track)) The mast not being in column then creates far more stresses on the rig ..

 

Not an expert ..just get paid to do it 

 

cheers. 

 

(ps..the perhaps counter intuitive thing with the mast loadings.....the lower the stay the greater the load due to angle / leverage. ...and it is vitally important that the lower section do not stray out of column. It is why so many masts fail at the lower spreaders. ) I will shut up now 

[Island Time 1,230]

Silly question here ,is the 2 mtr measurement on all size rigs ,

As IB said, the 2m section is just convenient. Most people can reach up 2m. The stretch table for standard 1x19 and 1x19 dyform is given in my earlier post. But generally the stretch is the same for all sizes (but of course larger wire is harder to stretch, loads are more, but elongation measurement is the same related to % of breaking strain), provided its 1x19.....

[Myjane 40]

Thanks all for this learning curve , what I will do is one step at a time. Sail being cut down a 100 mills as it was topping out between the tack and the head if the furler and not getting the halyard tension More kiwi slides are being fitted they were two far apart so I will be able to tension the furler foil tighter so may look better on the stay , I had put a turn on the forstay earlyier , so will try it again with the updated sail , my back stay doesn’t have a continuous Y stay with the pull blocks linked to pull on tension , it has a broken Y with the block purchase in the Y I may have to change that to the latter. ,as it is I can undo the jammer and there is no tension on the back stay at all ,just floppy , the cap tensions will check after all this if the prob persists, somewone said go for a 8 mill rod on the forstay it will hold shape better with the foil , don’t know. ,will try the one step first