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Seakeeper and Sea Ray: The Math of Gyroscopic Stabilization


I’ve always been fascinated by the technology in Seakeeper gyro stabilizers. Stabilization in general is part of boating and always has been, since the first shipwrights figured out how to make their boats more stable (using hull design) and therefore more pleasant to be on and safer in all conditions.

Now I admit that no small part of my fascination here is a personal inclination to occasional seasickness. If you’ve ever succumbed, you know it’s something you would not wish on your worst enemy. So the seemingly ever-growing segment of the boat business dedicated to stabilizing boats says to me that even the saltiest among us may sympathize with the unpleasantness that goes along with mal de mer.

Stabilization is something that you feel. And only feel. We can’t really show it in photos, and we really can’t write about it so you fully understand. Even video fails to capture the onboard sensation (like the one I shot on a Seakeeper demo boat at the Ft. Lauderdale International Boat Show in 2014).

The best way to understand is to get on a boat equipped with it and have the captain show you the boat without stabilization, then turn it on, then shut it off again. Only then can you know what the system can do. And if you do sea-trial the system, hopefully you’ll get a day with some sporty conditions, so you get a sense of what to expect, should you install a system.

Seakeeper has always said its gyros can be placed anywhere on the boat, because each unit works independently in the way they detect the boat’s motion and move to counteract it (“precess” is what they call it). Also a boat can be equipped with just one unit—provided it’s placed so it doesn’t affect the running attitude of the boat adversely—or more than one.

And that brings me to my point, since Sea Ray installed a pair of Seakeeper M8000 units (a comparable model is now called the Seakeeper 9) for the new Sea Ray L650 Fly tested by Senior Editor Kevin Koenig in our May 2015 issue. I reached out to Seakeeper and Sea Ray to find out why the boat had a two-unit install.

Sea Ray L650 Fly

“When the 65 was first launched, we didn’t have the Seakeeper 16 available so the design was around two Seakeeper 9s,” says Andrew Semprevivo, vice president of sales and marketing for Seakeeper, in an e-mail. “The boat loaded is 43 tons, and as our Seakeeper 9 is only suited for up to 35 tons, we need two units.”

“Seakeeper’s evolved and filled-out product line now offers builders great flexibility in gyro configuration,” Semprevivo says. “Meaning, in some cases one space large enough for a [Seakeeper] 16 can not be found so two Seakeeper 9s are used. Or there’s no available space for a single 9, but two smaller places for a pair of [Seakeeper] 5s.”

Sea Ray VP of Marketing Matt Guilford also e-mailed me his company’s take: “While we’re certainly interested in the 16 unit, one of the great benefits to an OEM partnership with Seakeeper is the flexibility of their product offerings to meet different design envelopes. It varies from boat to boat; sometimes it’s easier to incorporate two smaller units off of the centerline than it is to locate a larger unit on the centerline. Whenever we use the units prescribed by Seakeeper, we’ve been happy with the outcome and stabilization achieved.”

Comparing the Systems

According to Seakeeper’s Andrew Semprevivo, the price of the two-unit Seakeeper 9 installation would be about $133,800 while the single Seakeeper 16 would be around $89,000. That gets you the single unit, which is a simpler system with a single keypad control head, and that uses 3 kilowatts rather than 4 kilowatts for the pair. The single is also 200 pounds lighter, weighing in at 2,200 pounds rather than the pair tipping the scale at 2,400. And the single is cheaper to maintain. But the pair of Seakeeper 9s has the redundancy all experienced boaters look for, and also has 12.5-percent better performance by the company’s measurement.