Vectran steering cables

[Asylum]

Wheel steering on my 38 foot racer is via a short chain on sprocket on the wheel - the chain then connects to two vectran cables that run through turning blocks and back to the rudder post quadrant. The chain connects to the vectran by spectra lashings. The lashings have to be adjusted to account for stretch fairly frequently. The kind of boat that I have (Sydney 38) has had a number of failures of this system. Some of the failures have been caused by the vectran cables rubbing / chafing on each other and eventually parting. They touch where they criss-cross on the way to the quadrant. Other failures have been from breakage of the lashings.

I'd like to make two changes:
1) I'd like to put some kind of thin jacket over the vectran where they can rub and chafe. The jacket may make the rubbing slightly worse but would be intended to protect the vectran "core".

Any opinions about this 'fix' would be appreciated.

2) I'd like to replace the lashings with some small stainless or bronze turnbuckles - both to minimize the chance of failure and to make it easier to adjust the steering. Again - any thoughts on whether this is a good idea are welcome.

The last thing that I may be able to do is to slightly move (raise) one of the turning blocks that the vectran runs over to provide a bit of clearance between the two cables at the crossover.

[Brian Duff]

iI your leads are fair, an the sheaves and quadrant smooth (like sand to 400g smooth) then chafe should not be a problem. Moving one of the sheaves down a 1/4" or something to eliminate the rubbing at the crossover is a good idea, as long as you can maintain fair leads. You can also get great 'thin cover' with a messenger in it from Yale Cordage - available through any rigger and many marine retailers.

The lashings connecting the chain to the vectran do not make sense. Steering systems are usually adjusted at the quadrant with an eye bolt, as the chain termination is usually inside the pedestal and not accessable. One common problem with these systems that we find is that the rudder stops are not placed correctly, such that the end of the chain is allowed to ride onto the sproket on the wheel axle that drives the system by over steering. The sharp tips of the sproket will crush and break stainless cable, and I imagine effectively cut vecrtan as well. Be sure your chain ends cannot get onto the sproket. That said, if you are thinking a turnbuckle might work here, then this must no be the case on your boat, and the chain ends must be operating in the clear below deck.

Stretch should not be a problem with that system - we use vectran to replace stainless cables in many rigging applications, and find it to be less stretchy than stainless. Perhaps your lashing knots are working loose?

just some thoughts to consider -

[Asylum]

As a matter of interest, the rudder stops are a single piece of 6mm spectra that goes from the centre point of the quadrant to a fixed padeye on a strongpoint about 400mm forward of the quadrant. It's length prvents the quadrant from turning more than nn degrees.

Thanks for the input. I think that the system loosens up because we're not getting the lashings tensioned enough, hence my thought about the turnbuckles.

Anyway - thanks for validating my plan - I'll check back with results.
Meanwhile if you hear about a boat going out of control in Australia because the owner made mods to the steering system, it may be me :-)

By the way - the builders (They've built 70 of these boats here) says that they just recommend changing the Vectran frequently and changing the lashings more frequently. They said they saw no problem with the turnbuckles so long as I make sure that they can't run over the sprocket or into the sheaves.

[Brian Duff]

that spectra strops is very effictive rudder stop. we use those often on all types of boats - just put one in a catalina 42 last week.. anyway


your builders are right, you can use turnbuckles, but make sure that if the turnbuckles are working on a horizontal plate, that slack in the system will not cause the weight of the turnbuckle to pull the vectran off the sheaves or quadrant.

i think your best bet would be to use a straight legth of vectran from splice to splice hooked directly to the chain an the eyebolt at the quadrant.

fun stuff

[matt the rigger]

Mr. Duff is correct in what he said about the connection to the chain. That connection should not get any where near the turning blocks or the quadrant. On the lashing end, I have found in the past on many number of race boats that no matter how tight you get the lashing. It will all ways loosen up over time, do to the pressure on the system. One way I've found to fix this is to not use a low stretch line like spectra for the lashing. Instead I would use a more stretchy material like 3\16" or 1\4" braided nylon. As long as you have 8 to 10 wraps on the lashing it is PLENTY strong enough. This will keep the constant pressure needed on the vectran to keep it on the quadrant. Also make sure that the rudder stop strop is still the right length. It can,and will grow over time. I think the best way to eliminate the chafe on the vectran is to replace it with 7x19 wire. It will do the same job,but last a lot longer. Hope this helps.

[Brian Duff]

good suggestions Matt, about using something like polyester for the lashing. we have been trying that with dux rigged boats, using polyester for the lashings in the deadeyes allows us to keep tension at rest... same theroy

[Brion Toss]

Hello,
First, I originally heard about Vectran for lashings in connection with lightning strikes; people who had wire tackle were being blown off the helm from a bolt coming up the rudder post. Vectran was used because of its high melting point (which means that the Spectra lashings are not necessarily a good idea). It sounds, in this case, as though the builders made the transition without taking the characteristics of of the HM into account. Vectran has essentially no creep, and the multiple turns on the lashings and their short run should eliminate Spectra creep, so that leaves constructional stretch as the likely culprit.
In addition, the fact that the lines are chafing at all seems to indicate that the system was simply not worked out well. Recommending frequent replacement of the materials sounds like a way of acknowledging the problem by saying, "Them are like that," without addressing the root causes of the problem.
Going back to wire might seem tempting, but that means going back to wire's downsides, including fatigue and conductivity. Therefore, assuming there's no slop in the axles and such that might account for slack, I agree that Polyester or Nylon lashings should do the trick. Assuming, of course, that the constructional stretch is taken out of the equation and the leads are corrected.
Fair leads,
Brion Toss

[Asylum]

Thanks to all of you. I now feel like I can go about solving the problem.

[Brian Duff]

I second what :"Big B" said

[mrgnstrn]

To eliminate the chafe where the Vectran Crosses, put in a simple upright block, like a Harken 096. This will push one of the lines up (or down) to prevent them from touching.

Everything else can be same as designed.

A friends Hunter 45 had a similar issue, only their wire chafed thru, during the "bringing it home from purchase" delivery from Porto Rico to New Orleans, during a nasty gale.
They got to use the emergency tiller on a 25000 lb "dinghy". HA!

First purchase after the new wire was the 096 block to prevent them from touching.

-M