[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 -