Catamaran Steering System

Contains designs for parts of the steering system of a composite catamaran TEK-45 (AKA Tektron 44) built by TEK-Composites in 1998.

Mostly made public as an example for other boat owners, to borrow ideas and designs from.

The vessel has two steering wheels.

Components:

• helms
• roller chains
• stainless steel cables
• pulleys
• radiants
• bearing bushings
• rudders

Quite basic, yet very reliable and easy to maintain.

Helms

Two stainless steel helms by Edson Marine.  Each helm has a sprocket and 520 ANSI roller chain that translates rotating motion into push/pull force to the cables.

Radials

There're two radials, 400mm in diameter, 24mm thick.  There's a square cutout in the middle for rudder post, 50mm wide.  Each radiant has stops, mounted using bolts that go through its body.  Grove for stainless steel cable all the way around, metal corners where the cable bends.  Autopilot mounts for angle sensor and hydraulic actuator on starboard side.  The radials incorporate Ackermann steering geometry, meaning a slight offset to produce differential between two rudders when turned to either side.

Rudders

Two identical unsinkable carbon fiber foam core rudders.  Round post, square stainless steel mounting shaft (50mm).  There's a PTFE “washer” (spacer) between the top bushing and the radial.

Bushings

Two bushings per post, four in total for the entire system.  They “hug” stainless steel cylinders on the post, remain glued to the socket (hull).

References

• https://jefa.dk/products/rudder-blades/