Gyro Stabilizer for Boats

Gyro stabilization is becoming increasingly common on boat builds and refits.


November 13, 2019
Seakeeper Gyro Boats
Boatbuilders such as Viking now incorporate gyros as an integral piece of the design process, with a designated location should an owner want to add one. Courtesy of Viking Yachts, Forest Johnson

Perhaps three of the biggest features in the history of the sport-fishing boat — besides hull design — are the flying bridge, tuna tower and mezzanine. But now, a fourth is changing the game: gyro stabilization. If builders want to sell a new boat these days, they’d better darn sure plan on installing a gyro. Different-sized boats can handle gyros, including stabilizers for small boats.

History of Gyro Stabilizers

The first experimental gyros were developed in the late 1860s and into the early 1900s, with less than desirable results. Several large ships used the technology, including USS Henderson, a military transport ship, in 1917, which had two 25-ton units, and an Italian cruise liner utilized three large units in 1930. The cost and weight of the systems were prohibitive, and other forms of stabilization became more readily available. External fin stabilization, which used the speed of the vessel to help create anti-roll stabilization, became more popular, but by no means more practical — ­especially in sport-fishers.

How Does a Gyro Stabilizer Work?

The gyro stabilizes the boat through the energy it creates spinning a flywheel at high revolutions per minute. The subsequent angular momentum, or stabilizing power, is determined by the weight, diameter and RPM of the flywheel and measured in Newton meters — a unit of torque. The output rating in Newton meters is the amount of power the unit is capable of generating to stabilize the boat. The more output, the more anti-rolling torque generated by the gyro to stabilize the boat.


Seakeeper Continues to Expand Its Product Line

Several companies make gyros for sport-fishing boats, and they have units to fit almost any application in the sport-fishing industry. Seakeeper, the fastest-growing brand, offers units for practically every size sport-fishing boat made today. In a 10-year period, it not only created demand in the new-boat market but retrofit all kinds of boats.

Mitsubishi Gyros
Mitsubishi’s gyros are self-contained, with no external parts or need for raw-water cooling. Four models are available to fit a variety of vessel sizes. Manufacturer

An aggressive new period of product development advanced technological qualities as well as reduced the overall size of each unit and reduced costs. The company’s latest offerings include the Seakeeper 2 for boats 27 to 32, Seakeeper 3 for the boats 30 to 39 feet, Seakeeper 5 for boats 40 to 45 feet and up to 20 tons, the Seakeeper 6 for boats 46 to 52 feet and up to 24 tons, the Seakeeper 9 for 50- to 59-footers up to 30 tons, the Seakeeper 16 for 65- to 69-foot boats up to 50 tons, the Seakeeper 18 for boats 65 to 75 feet and up to 56 tons, the Seakeeper 26 for boats from 70 to 84 feet and up to 75 tons, and the Seakeeper 35 for vessels over 85 feet and 100 tons. The additional compact designs allow for multiple-unit installation to meet tonnage requirements and space limitations of most boats, and they can also be mounted off the centerline to fit a variety of applications.

Perhaps the most exciting is Seakeeper’s Heavy Duty Line, engineered for rigorous use of more than 1,000 hours per year. The Heavy Duty Line includes the Seakeeper 7HD for boat 45 to 54 feet, Seakeeper 12HD for boats 55 to 64 feet, Seakeeper 20HD for boats 65 to 74 feet, and Seakeeper 30 HD for boats over 75 feet.


Seakeeper does require a raw-water cooling system for its units, as well as DC power and AC power through an inverter to power the controls.

Mitsubishi Gyro Stabilizer

Mitsubishi also designed anti-roll gyros for the sport-fishing market. Now called the Tohmei Anti Rolling Gyro stabilizer, manufactured by Mohmei, its unit only require bolting to the boat and plugging in. Its unit is completely self-contained, with no external moving parts and no need for raw-water cooling. Tohmei Anti Rolling Gyros come in four models: the ARG50T/65T, the ARG175T, the ARG250T/250T-1, and the ARG375T.

Each company’s recommended installation procedure must be adhered to for the units to work properly. The torque generated by the flywheel requires the units to become an integral part of the boat and be tied into the main stringers and strengthened areas of the boat. This makes retrofits difficult. Only the original builder or an experienced boatyard should do this kind of work because they have the capability to integrate the mounting system into the structure of the boat. However, a large portion of Seakeeper business is retrofits, so the opportunity is readily available.


Gyro Stabilizers Have a Major Positive Impact on Your Day’s Fishing

I have ridden several boats with gyros and most recently spent time on a 66-foot Viking. The boat reacted as expected in a beam sea, with some roll and snap, while sitting with the unit on standby. Once the Seakeeper unit switch was flipped, she tightened up and bobbed like a cork, with little roll or yaw. As I said before, it will be hard to sell a boat without an anti-roll gyro from here on out. If you’re ordering a new boat, bite the bullet and install a unit. It’ll make days on the water more enjoyable and help your resale.


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