Stabilizer Preventive Maintenance

A seemingly complex system is easy to maintain.

Maintenance 001It’s not surprising that most of us find the gentle, rhythmic motion of our boat one of the delights of being on the water. After all, we experienced this type of movement well before we were born. However, repetitive rolling can become intensely uncomfortable and, in the extreme, dangerous.

Years ago, boaters either rigged small steadying sails or deployed flopper-stoppers, metal plates called “fish” towed from the end of booms swung out to port and starboard, to provide roll-resistance. Today’s stabilizers are hydraulically driven fins that mount on your boat so when the boat rolls, the fins turn like a rudder to provide a greater amount of stability. The faster the speed, the more effective they are. Conversely, a fairly new type of stabilizer is an at-rest stabilizer that provides smoother anchoring. Although different companies make stabilizers with their own slightly different features, they are all, for the most part, the same in effectiveness.

Stabilizers are complex systems, with sensors linked to movable fins through a hydraulic system. When a sensor detects the start of a roll, it signals the hydraulics to deflect the fins; water pressure on the fins creates a force opposite to the direction of roll, thereby damping it. These amazing and complex cruising aids are designed for reliability and require little maintenance that can be performed by any skipper with a little mechanical ability.

Prior to each use, check the hydraulic fluid level, prior to starting the main engines, so the oil temperature is cool. Keep in mind that as the oil warms during operation it expands and its level will change. Add clean oil if necessary. Hydraulics are very sensitive to dirty oil, so use clean oil poured from a clean container through a clean funnel. Adding oil should be infrequent, so if your stabilizer’s fluid level keeps dropping, check for leaks. It’s also a good idea to perform a walkthrough and visual check of all stabilizer system components. Keep in mind that the fin actuators, the mechanical assembly that drives the fins, are sometimes under cover. Some people tend to overlook these. Check to be certain all looks good and there are no loose connections or hose chafing in the area. Be certain that the bonding wire is still attached to the fin actuator assembly, to help prevent galvanic corrosion.

While operating the system, check for leaks around all fittings, pumps, valves, motors and hydraulic cylinders, and make sure all the hoses are in good condition. Lubricate the system; consult the manual for the location of grease fittings and for the type of grease to use. Check that cooling water is flowing freely. Some systems are equipped with a dedicated cooling water pump. Most are a centrifugal type and do not require impeller maintenance. A self-priming impeller type will require you to check the impeller on a regular basis and change it if necessary. If the vessel is hauled for any reason, the cooling water pump may need to be primed. It’s a good idea to check prior to operation.

Manufacturers recommend scheduling a trained service technician to change the hydraulic oil, the filter element every two to three years, and replace the lower shaft seals during a regularly scheduled haulout.

Once you’ve gone cruising with stabilizers, you never want to go to sea without them.