Steering sheaves / pulleys

[casual]

The weakest part of the system is the end link of the chain.Edson has a new quadrant system that eliminates all the chain cable pulleys ect. Might want to take a look. No I, am not a seller.

[coopec43]

Originally Posted by casual

The weakest part of the system is the end link of the chain.Edson has a new quadrant system that eliminates all the chain cable pulleys ect. Might want to take a look. No I, am not a seller.

Thanks for that but it sounds like conduit?


The experts have specifically warned me against that as you cannot monitor the condition of the cable and they pointed out that you don't use plastic coated lifelines on boats for the same reason. But I'll check it out anyway..


Clive

[johnmort]

Originally Posted by jkishel

Correct, the force on the rudder could be several thousand pounds, but the force on the wire rope itself is much less. The resultant force on a spade rudder turned hard over is located several inches aft of the centerline of the stock and the quadrant is much larger than that. For example, with an 18 inch radius quadrant and a resultant located 2 inches aft of the stock centerline, the mechanical advantage is 18/2 or 9. With 3751 pounds on the rudder per the previous post, the load on the wire rope would be 3751/9 or about 417 pounds.

The breaking strength of 1/4 inch 6/19 wire rope is around 5000 pounds. this may seem like a lot for a 417 pound design load, but with an appropriate safety factor and strength reduction due to u-bolt clips and chain connections, this could be about right.

We offshore race most common failure on participants is boat steering, every race with out exception one or more sailboats retire from the events with steering problems!
Consult with the manufacturer to make sure you have this project correct.
Side note if using Dyneema line for steering cable like Beneteau does,make sure it is of a flat section not round,
The loading on the circumference of the Dyneema is asking for failure.