BoatingLocal’s Tom Richardson stopped by the MacDougalls’ Cape Cod Marine Service booth at the 2011 New England Boat Show to talk with Director of Customer Services Tim Shields about the remarkable Seakeeper anti-roll gyro-stabilizer system. MacDougalls’ was recently certified as an official dealer and installer of the Seakeeper gyros, which are designed to reduce boat roll.
As Shields explains in the accompanying video, the Seakeeper system is typically installed on larger yachts, although smaller vessels can also benefit from the gyro-stabilizer, which is available in 2 sizes. Prices run from $70,000 to $120,000, with the average install of the smaller unit typically running $20,000 to $30,000.
So, how does it work? Naturally, there’s a lot of complicated physics involved. The Seakeeper website explains the product’s ability to counter roll thusly:
“The gyroscope has 3 axes: a spin axis, an input axis and an output axis. The first is the axis in which the flywheel spins. In the Seakeeper gyro, the spin axis is vertical. The input axis is the axis via which inputs are applied. In the Seakeeper’s case, the principal input axis is the longitudinal axis of the boat, since that is the axis around which the boat rolls. The principal output axis is the transverse (athwartship) axis around which the gyro rotates, or precesses, in reaction to an input.
“The roll of the boat inputs information to the rapidly spinning gyro, causing it to generate rotation around its output axis. The spin axis rotates to align itself with the input axis. This output rotation is called precession. In the Seakeeper’s case, the gyro is rotating fore and aft around the output, or gimbal, axis.
“Two hydraulic cylinders coupled to the gyro’s gimbal axis act as a brake, which controls the gyro precession rate and counteracts the boat roll.”
Got that? Yeah, me too. The important thing is that it works (watch the video). Shields—a reliable friend and experienced boater—tested the product himself in Florida, and said the results are nothing short of extraordinary.
Seakeeper gyro-stabilizers are ideal for anyone who has the money and spends time anchored, drifting or cruising in rough water, and have been shown to reduce seasickness for some people. Seakeeper recommends that the gyro unit, which weighs around 1,000 pounds, be located in a soundproofed space aft of amidships. The space must contain a mounting position that has “sufficient structural coupling to transmit the gyro’s righting torque safely to the hull structure”. However, the gyro does not have to be located on the centerline of the boat to be effective.
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