Anchor Windlass Product

Overview

An anchor windlass is the deck machine that deploys and recovers a vessel's anchor and rode. In a vertical windlass the drive axis is perpendicular to the deck: the motor and reduction gearbox hang below in the chain locker space, while only the Deck Unit with its chain wheel and warping drum shows above deck. The chain wraps 180° around the Gypsy Wheel (Chain Wheel), which gives better engagement than the 90° wrap of a horizontal windlass and keeps the heavy components low.

The machine is sized by maximum pull, conventionally specified as at least three times the combined weight of anchor and rode. A unit rated 1000 kgf suits a 12 m cruising yacht carrying a 25 kg anchor and 60 m of 10 mm chain. The windlass is not intended to hold the boat at anchor: once set, the load is transferred to the Chain Stopper or a snubber line so the gypsy and gearbox see no sustained shock loading.

How it works

Hauling current flows from the battery through the Windlass Circuit Breaker to the Reversing Solenoid Box, whose paired contactors reverse polarity to the Drive Motor for up or down. The motor is series-wound because the configuration produces maximum torque at stall, exactly what is needed to break an anchor out of the seabed; the trade-off is current draw that can reach 150 A, which is why the supply uses 35 mm² cable and why engines are normally kept running while weighing anchor.

The Motor Pinion / Worm Shaft is a hardened steel worm meshing with the Bronze Worm Wheel in the oil-filled Reduction Gearbox. The roughly 70:1 reduction multiplies torque and, because a worm mesh of this lead angle cannot be back-driven, the gear train self-locks: a loaded chain cannot spin the motor backwards. A secondary Helical Gear Pair trims the final ratio, and Oil Seals on the output shaft keep the EP90 Gear Oil Fill in and seawater out.

Torque reaches the deck through the Mainshaft, a 28 mm 316 stainless shaft running in two Ball Bearings inside the Base Casting and sealed by the Deck Seal. The gypsy is not keyed solid to this shaft. Instead the Clutch & Brake couples them: tightening the Clutch Adjusting Nut clamps two tapered Clutch Cones against the gypsy hub so it turns with the shaft. Backing the nut off frees the gypsy, letting the anchor free-fall under gravity while the operator modulates descent with the same cones acting as a friction brake. The Emergency / Clutch Handle both adjusts the clutch and, fitted to the Drum Cap Nut, cranks the windlass manually if electrical power is lost.

Chain handling

The Gypsy Wheel (Chain Wheel) is the one component matched exactly to the rode: its five whelped pockets are machined to a single chain calibration such as 10 mm DIN 766, and running mismatched chain causes jumping and accelerated pocket wear. The spring-loaded Chain Pressure Arm presses the chain into the pockets through the wrap, and the fixed Chain Stripper then levers each link out of its pocket and deflects it down the Chain Pipe into the locker. Without the stripper, wet chain tends to ride around the wheel and jam.

Above the gypsy, the independent Capstan Drum handles rope. Its concave Drum Body takes three or four turns of warp for kedging or docking; because the drum is keyed to the shaft while the gypsy is clutched, the drum can haul line while the chain stays put.

Controls and monitoring

Operation is by momentary Deck Foot Switches set flush in the foredeck, with guarded covers, wired in parallel with a Helm Rocker Switch at the steering station. The Reversing Solenoid Box keeps the heavy switching at the motor so control wiring carries only coil current. The Chain Counter counts gypsy revolutions via a Neodymium Magnet cast into the wheel and a Hall Sensor under the deck; its Microcontroller multiplies counts by chain pitch per revolution and shows metres deployed on a helm LCD Panel.

Installation and maintenance

The deck unit bolts through the foredeck onto the Backing Plate, with the Deck Gasket sealing the penetration; alignment matters, since the bow roller, gypsy, and chain pipe must lie on one line for the chain to feed cleanly. Routine service is modest: annual gearbox oil checks, greasing the clutch cones and Mainshaft splines, replacing the motor's Carbon Brush Set every few hundred hours of running, and freshwater rinsing of the deck components. The single most common failure mode is corrosion of the below-deck motor terminals in a damp chain locker, which is why the Motor Housing is sealed to IP66 and terminals are kept coated.