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CAN Newsletter magazine

Calming the seas with CAN

For non-boating experts, it may be a surprise to learn that boats don’t have to make that seasickness-inducing roll anymore. There is a way to use angled fins to oppose the rolling force of the waves.

(Photo: Seakeeper)

This article originally appeared in the September issue of the CAN Newsletter magazine 2018. This is just an excerpt.

Maximizing stability has both practical and comfort benefits: it’s safer and more pleasant for all onboard, whether you happen to be hauling in fishing nets, patrolling heavy seas, or drinking champagne on a luxury yacht. The traditional “anti-roll” solution is a set of movable fins that sit externally at either side of the keel. Whether fixed or retractable, these angled fins generate a corrective hydrodynamic force that opposes the rolling force of the waves. The solution is speed dependent, with specification requiring that fin size is balanced with the projected cruising speed.

A relatively new kid on the block is Seakeeper’s gyro stabilizer. It is a computer controlled gyroscope that eliminates most boat roll, including the fatigue, anxiety, and seasickness that go with it. The calm-inducing combined hardware and software system can be installed virtually anywhere on the boat, because it requires no external equipment outside the hull. A gyro stabilizer works by spinning a flywheel inside an enclosure at high speed, creating an inertial force forward and aft that counteracts the side to side roll. A major selling point is that it will work at any speed, even when the boat is stationary.

Seakeeper has developed a particularly sophisticated anti-roll gyro that eliminates up to 95 % of boat roll on vessels 8 meters and up. A unique feature is its vacuum-sealed enclosure, which protects the gyro’s flywheel, bearings, and motor from the marine environment and facilitates a smaller, lighter, and less power-consuming design. This solution uses the CAN network to coordinate a distributed control system. Among the attributes that set Seakeeper’s gyro apart from competitor solutions is its “smart” nature, whereby it automatically gauges variables including sea state and boat speed, then optimizes performance quasi-instantaneously.

Explaining CAN’s role in the Seakeeper control system, Bob Lawrie, Director of Advanced Projects at the company: “We use the CAN bus to coordinate various sensor readings and actuator outputs to optimize stabilization. Our CAN network has a system controller, an IMU (which senses boat motion), a drive (which powers the motor that spins the flywheel), and a user interface display. We also have a second, electrically isolated CAN bus located in the user interface display that allows replication of the user interface functions on larger display screens.”

During control system development and testing, Seakeeper used a combination of the Kvaser Leaf Light Rugged and Kvaser USBcan Light 2xHS to connect to their calibration tools. Recounts Lawrie: “As a calibration tool interface, these provide access to all data needed to monitor and log data, adjust calibration parameters, and optimize the control system. We also use the Kvaser interfaces to log data to proprietary software during our final assembly test qualifications and to program the controllers on the CAN bus during production and for software updates in the field.”

If you want to continue reading this article, you can download the PDF of Vanessa Knivett. Or you download the full magazine.


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