Engineer’s Angle: Anchor gear may be brutish, but it still requires loving care

Jul 27, 2019 by JD Anson

Engineer’s Angle: by JD Anson

The anchoring system is, by function, quite robust. It has to be able to raise not only the anchor, but several hundred feet of chain from the ocean bottom. It must secure the ship in high winds and seas, and keep it securely fastened to the bottom. But because it is so strong, it is rarely given the attention it needs to continue to perform. No one wants to have to pull in a couple hundred feet of chain when the windlass decides to take the day off.

Whether a small 12-volt tender windlass or a mega yacht windlass/capstan combination, an annual service needs to be performed – at the minimum. This should consist of disassembly of the above deck components. Be sure to photograph and label all parts as the come off to ensure they all go back to their correct positions. There’s nothing worse than finishing a reassembly to find a spare spring. Removing the capstan will allow visual inspection of the brake and clutch pads to check for wear. Checking the manufacturer’s specifications will tell when replacement of these pads may be necessary. 

This is also a good time for some crew bonding by offering the deck crew the opportunity to give the chrome a good polishing when access is much easier for them. They can get all those crannies that usually are letting down the overall appearance of the deck jewelry.

Below decks, the gearbox oil should be checked for water intrusion, which could indicate a failing shaft seal above. This can be determined by draining off a small bit of oil from the bottom, checking for milkiness in the oil, or dipping a rod coated in water-finding paste to the bottom of the reservoir. 

The time to replace the seal is when the above-deck components are already apart. Changing the oil is usually not required unless contamination is found. These gears are used very intermittently compared with a transmission. It will take a decade to get to even 100 hours of run time on most boats.

Yachts tend to be evenly split between electric motor-driven and hydraulically powered windlasses, and each has its own requirements for service. Hydraulic motors are driven by the ship’s system, and thus require less direct maintenance. Look for rust or corrosion on the plumbing and the motor and keep as clean as possible. Listen for abnormal sounds. Usually there are two windlasses, so comparing the performance to each other can help indicate any issues. 

Electric motors need to be kept dry. If they are rusty or corroded on the outside, they are probably corroding on the interior. On an AC motor, a quick megohm test of the windings will indicate the condition of the windings insulation inside and help determine if service is necessary. These motors are driven by frequency drives, and these should be checked for proper function as well. An AC clamp meter on the phase lines can help diagnose overloads due to electric problems or mechanical issues.

Back above deck, a thorough cleaning and re-greasing of the moving components (NOT the clutches or brakes) before reassembly will make future use a breeze and will get a thumbs-up from the deck crew when they are anchoring in foul weather. Be sure to use a waterproof grease, as these parts tend to spend a bit of time submerged when green water comes across the cap rail in heavy weather.

Now that all the shiny bits are squared away, its time to inspect the rough stuff. The anchor chain link diameter should be measured at several points along its length. Dragging across rocks and being pulled through the wildcat will wear on the metal, causing it to weaken. A variation of 8% from the diameter when new calls for an end-to-end swap of the chain, as the front part is used more than the bitter end. Chain manufacturers and class societies require replacement of the chain if worn much more, usually to 83% of new trade size, i.e. 20mm chain must be replaced at 16.5mm thickness. This is because the metal becomes weaker as it thins from wear.

When possible, dropping the anchor onto the hard allows inspection of swivels, detachable links and anchor stock joints for binding or wear. While anchor gear is brutish, it still requires attention. Ignore it at your peril.

JD Anson has over 20 years of experience as a chief engineer on megayachts. He is currently project manager at Fine Line Marine Electric ( in Fort Lauderdale. Comments are welcome below.