Construction of the Windvane Self Steering System

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Description / Materials

Castings

All LM 25 aluminium alloy, which contains 0.48% Magnesium for strength and corrosion resisting qualities, with anodized finish.

Machining

For standardization, CNC computer controlled machines are used.

Tubes

Aluminium grade 6063, with anodized finish

Shafts

Grade 316 stainless steel – polished finish

Bearings

Machined out of Vesconite or Vesconite Hylube with PTFE self lubricating qualities. These materials are used in ocean liner stern tubes and stern gear.

Gears

Du Pont Delrin 100C010 Injection moulded UV stabilized Acetal

Course Adjusting

SHORT CRANK – 60 mm long. This is fitted directly to the worm.
LONG CRANK – This incorporates a flexible coupling using 16 ID push lock hose, which has a 450mm extension with a crank on the end.
One turn of either crank represents 6 degrees course change.
OPTIONAL LINE COURSE ADJUSTER – A line is used to adjust course and each pull of 12 cm (4 inches) produces a 2 degree course change.

Airfoil

6mm Marine ply, finished silver/grey to match gear. It is machined with a 100mm slot at the lower end, allowing adjustment to suit the weather.

Application :

  1. In heavy weather, to dampen the airfoil movement, lower it in the counter-weight clamp and tilt it backwards, as required.
  2. In light winds, the sensitivity can be increased by raising the airfoil and keeping it perpendicular at the top of the slot

Glass reinforced plastic ( 180 x 920 x 23T) silver/grey finish, with 2 nylon shear screws, which will shear, should the rudder strike an object in the water.

Servo Linkage From Airfoil to Pinion Gear

Double supported on 4mm stainless steel shafts for low friction.

Weight

Model M650 (mk2) 16 kgs
Model M790 (mk2) 17 kgs
Model M950 (mk2) 18 kgs
Model M1070 (mk2) 19 kgs

Stowage

The 30 mm diameter main shaft spigots into the mounting boss and is held in place by a 12 mm pointed cap screw, which fits into the dimple in the 30 mm shaft. If this cap screw is loosened, the whole gear can be slipped off for easy stowage. When the Neptune is not in use, the rudder can be rotated 180 degrees (see right), to stand erect, out of the water.

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