Trevor Thompson

My last post contained errors. The errors don’t change the outcome but for anyone with a vaguely scientific background there are glaring. So to correct it (I tried editing the post but the system wouldn’t do it.)

the 100 kg that the helm can apply to the tiller has to be converted into a force in Newtons

F = m x g so F = 100 x 9.81 = 981N

The torque on the TILLER stock is T = F x L = 981 x 1 = 981 Nm

The force on the wire is 981 / 0.075 = 1308N

The safe working load for the wire was given in kg – as if a weight was hanging on the end of the wire.

So that force on the wire of 1308N can be converted to a weight using F = m x g transposed to m = F / g

So m = 1308 / 9.81 = 1333.33 kg.

That is 92% of the safe working load for the wire.

Why have I calculated this? I think I have established that a helms person cannot apply enough force to overload that wire – but they could get close to its safe working load. This applies whether the blade is up or down. If it is up you cant apply enough force to exceed the wires safe working load – the rudder blade will control the tiller not you.

The situation is very different with the tiller held still by ropes. The raised rudder blade can exert sufficient force on the wire to exceed the wires safe working load.

My conclusion remains as per the last post. Repeatedly exceeding the safe working load of the wire is bound to reduce its working life and lead to premature failure.