I have been using 8mm double braid for the control lines on Morning Bird's Fleming wind vane steering. It works well but on longer passages it stretches a lot and needs to be adjusted regularly.
The optimum rope will be non stretch, flexible to go around the blocks on the Fleming and in the cockpit and low weight/friction. I thought of using spectra but it doesn't seem flexible enough.
Whitworths have a Usacord double braid in their catalogue. Anyone got any experience of it?
Can the brains trust suggest a good rope? I'll need about 20 metres of it to allow for a spare set.
I use 5mm Spectra through roller bearing blocks. I have Spectra mainly because the local marine business only stocks Spectra, it's best you know! 6mm double braid would be more than adequate. I have a twin cleat system on the end of my tiller so I can adjust any slack out individually or if I want to adjust overall slackness just lift up the tiller slightly.
How about Dyneema Ocean 12? This is single braid dyneema (=spectra). 4mm has a breaking strain of about 2t, more than 8mm double braid. But I'm sure the 3mm, at 1.1t, would be plenty strong enough. It is incredibly light, has low stretch, flexible and slippery, and very easy to splice.http://www.ropegalore.com.au/4mm-dyneema-rope-sold-per-metre-free-delivery/
I'm not familiar with the application - if you need to apply significant tension by hand, this stuff would be no good on its own although you may be able splice on a tail of double braid.
Its more about reducing friction through turning blocks and reducing bulk if you have wheel steering. The breaking strain is not really a concern.
Hi
For what its worth, George, who owns and makes the Flemming (I have one, but dont use it) and who installed mine used I think either 6 or 8 mil blue with a white fleck,
As I said for what its worth
PS Wheel steer
Select to expand quoteMorningBird said..
MB has a tiller.
I am so glad to hear that. Is it as disgustingly phallic as the one in the video?? 
Select to expand quotecisco said..MorningBird said..
MB has a tiller.
I am so glad to hear that. Is it as disgustingly phallic as the one in the video??
Would not have noticed that till you mentioned it! Chain link is quick and easy but there are times when a slight variation in weather helm needs only one side adjusted slightly. Two jam cleats make this much easier.
This is my video. The two jam cleats are near the end of the tiller. There are 3 turning points for the control lines so I can alter the ratio. Normally I use the centre one but sometimes when sailing directly down wind I use the bottom one which gives a faster reaction time at the expense of less power. In the video the twin SS rods for the vanes tiller have been changed for a twin SS tube set up now after the original set up suffered some severe bending on a heavy breeze day.
Having seen the videos, the 3mm Dyneema would be more than adequate re strength and stretch, and the smaller diameter gives increased flexibility round the blocks. It's incredibly light. The only drawback would be because of its slipperiness it does not take a knot or cleat well. You could splice a loop in each tiller end though (it's trivial to splice), and perform final adjustments with some lashing between the Dyneema and the tiller (or chain loops).
Select to expand quotecisco said..MorningBird said..
MB has a tiller.
I am so glad to hear that. Is it as disgustingly phallic as the one in the video??
More so. Calm down, its legal not compulsory.
I bought some 4mm Dyneema. It is so much lighter than the old double braid so should reduce the friction and load in the system. I am expecting a big improvement in lighter airs with it in place. And it won't stretch.
Thanks for all the advice. I wouldn't have thought of Dyneema on my own.
