Rudders

A rudder is a device used to steer vessels or other conveyances that move through the water. Rudders operate by re-directing the flow of water past the hull, thus imparting a turning or yawing motion to the craft. In basic form, a rudder is a flat plane or sheet of material attached with hinges to the craft's stern, or after end. Often rudders are shaped so as to minimize hydrodynamic drag. On simple watercraft, a tiller—essentially, a stick or pole acting as a lever arm—may be attached to the top of the rudder to allow it to be steered by a helmsman. In larger vessels, cables, pushrods and hydraulics may be used to link rudders to steering wheels.

Boat rudders may be either outboard or inboard. Outboard rudders are hung on the stern or transom. Inboard rudders are hung from a keel or skeg and are thus fully submerged beneath the hull, connected to the steering mechanism by a rudder post which comes up through the hull to deck level, often into a cockpit.

Some sailors use rudder post and mast placement to define the difference between a ketch and a yawl, similar two-masted vessels. Yawls are defined as having the mizzen mast abaft (ie. "aft of") the rudder post; ketches are defined as having the mizzen mast forward of the rudder post.

Small boat rudders that can be steered more or less perpendicular to the hull's longitudinal axis make effective brakes when pushed "hard over." However, terms such as "hard over," "hard to starboard," etc. signify a maximum-rate turn for larger vessels.

A sailboat rudder is of particular concern to the surveyor because many are laminated of a combination of wood,  foam, and fiberglass. I find that many are saturated with water and punky. When sounded with a metal mallet a very dull "thud" sound is returned. Often they have cracks in the skin and some deep cracks into the laminate.

Rudder bushings/bearings are also a cause for concern as they are frequently overlooked or not even on the maintenance list. On most sailboats the rudder bushings are difficult to check, never mind change. Bushings have been made from nylon for years and are almost always shot in vessels over ten years old. If the vessel is hauled for the inspection, it is easy to check the bushings. First. try to lift the rudder to check for end play, then move the rudder, at the shaft, back and forth to determine side to side play.

 

If the bushings need to be replaced, the rudder must be removed (lowered)  from the vessel. Usually, because of the length of the rudder and shaft the rudder must be repaired in a boat yard so the vessel can be lifted, or if the vessel can not be lifted a hole must be dug under the rudder to drop it. This is a difficult procedure and is probably the reason most mariners avoid rudder maintenance unless a failure occurs. The rudder tube houses the rudder shaft and lower bushing. It is a tube which extends from the hull penetration to a point well above the water line. Using a rudder tube to house and support the rudder shaft eliminates the need for a device to prevent water from entering the vessel.

 

 

 

 

 

 

 

 

Rudder Pintles and Gudgeons

Pintles are a hook or pin on which the rudder hangs and turns. We carry bronze pintles, sized by the width between their straps, in 1/2 in., 3/4 in., 1 in. and 1.5 in. sizes. Bronze rudder pintles are used primarily to attach a rudder to the stern or transom of a sailboat. The pintles are designed to fit onto the rudder, pins facing down, and the pintles fit into the appropriate sized gudgeon, which is attached to the stern of the boat. Pintles are measured by the width between their straps.

                       

Gudgeons are a metal eye or socket attached to the stern post to receive the pintle of the rudder. We carry bronze gudgeons sized by the width between their straps.

 

Steering Quadrant

A wheel steering apparatus for a boat. A pedestal housing is mounted onto a cockpit sole or other support member. The housing supports a shaft and sprocket that are rotated by a wheel. A quadrant is mounted onto the rudder post that extends from the rudder. A chain and or cable linkage couples the sprocket and the sheave to pivot the quadrant as the wheel rotates the sprocket. The pedestal housing encloses the entire assembly. The apparatus is particularly suited to convert boats steered by a tiller normally attached to the rudder post to wheel steering

Typical Quadrant

Tiller

 

A tiller is a lever attached to a rudder post  of a boat in order to provide the leverage for the helmsman to turn the rudder. The tiller is normally used by the helmsman directly pulling or pushing it, but it may also be moved remotely using tiller lines.

As the size of boat increases the power needed to control the rudder via a tiller becomes excessive. In the 21st century, tiller steering tends not to be used on new boats with an overall length in excess of approximately 10 meters.

 

 

Rudder Support System

 

Bearing,  Rudder Log,  and  Rudder Shoe

 

Rudder tower

 

Power vessels that are equipped with inboard engines and direct or v-drives usually have small bronze rudders. Every rudder needs a device inboard the vessel which supports the upper section of the rudder shaft. On many older vessels a length of wood secured to the hull parallel to the transom  is equipped with rudder shaft bushings and performs this tasks until it becomes rotted. On newer vessels the rudder shaft support, (rudder tower) may be a metal bracket which is attached to the hull. Often this metal bracket is, believe it or not,  regular steel. This support system must be inspected with care because if it is  rusted or rotted and you break it you might own it.

 

         

 

The photo above is of a wood two by eight plank which is supporting the upper section of the rudder shaft. The wood must be checked for rot or other deterioration and must be well secured to the vessel structure.

 

 

The photo above is of a rudder post that was supported by a steel rudder tower.  The rudder tower has completely rotted away. This was a very popular SeaRay feature which is no longer used.

 

 

 

 

 

The photo above is of a solid bronze bar rudder tower which is supporting the upper section of the rudder shaft. This is a desirable arrangement and will probably outlast the vessel.

 

  

 

The photo above is of a steel rudder tower which was supporting the upper section of the rudder shaft in an earlier life. This arrangement of the steel rudder tower which was secured to the hull and steel control arm, (note red arrows) was standard

 equipment on many vessels for years. The tower in this photo has completely rotted away and the owner was unaware of this situation.

 

 

The photo above is of a solid steel bar  (lower red arrow) which is supporting the upper section of the rudder shaft.  Note the upper red arrow which is indicating a rusted control shaft and rusted hydraulic link assembly.

 

 

Rudder shaft control arm

 

The rudder shaft control arm is a short length of metal which is attached to the rudder shaft and then connected to the steering linkage. While the rudder shaft is usually bronze or some type of stainless material the shaft control arm is often made from steel. The control arm link bushing is also usually steel. This combination of this hardware often becomes rusted. Note photo above.