Boat rolling a problem? 'Smart' gyro to the rescue
4/22/2019

Maximizing stability at sea has both practical and comfort benefits: it’s safer and more pleasant for everyone onboard, whether they’re 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 located externally on both sides 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. Other methods are wing-like paravanes or ‘flopper stoppers’ that hang from outrigger poles to port and starboard and, in effect, anchor the boat in the water column. Paravanes are typically used to reduce or eliminate rolling while underway while flopper stoppers are deployed when stopped.

A relatively new entry on the ‘anti-roll’ block is Seakeeper’s gyro stabilizer, a combined hardware and software system that 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—up to 4700 rpm, that’s about 550 mph—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’s vacuum encapsulation enables the flywheel to spin roughly three times faster, cuts flywheel weight by two-thirds and halves power requirements,” according to the company.

Seakeeper has developed a particularly sophisticated anti-roll gyro that eliminates up to 95% of boat roll on vessels 27 feet and up. A unique feature is that 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.  Seakeeper’s solution uses a CAN bus to coordinate a distributed control system.
 
CAN has been the mechanism by which a host of electronic devices connect to each other via a central, high-reliability backbone to control complex electro-mechanical systems. The addition of a Seakeeper to the list of marine control systems that use CAN is welcome news to boaters looking for a smoother ride.

Sensing sea state and boat speed

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 Seakeeper Inc., says: "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. "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,” says Lawrie.  "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.”

Both rec and commercial vessels

Seakeeper caters to vessels from 7 tons up to 100 tons (the size of a small cargo ship or tug boat). Larger vessels can be fitted with multiple units to achieve optimal results. While the system’s sophistication may result in a higher initial investment cost compared to a traditional fin stabilizer, the benefits include increased stabilization at zero speed and reduced drag, which improve top speed, fuel consumption and range. The upkeep costs of a gyro are potentially also lower than an external fin as there’s no risk of snagging on marine detritus or seaweed, or damage from grounding when operating in shallow waters.
 
Seakeepers are regularly installed aboard new vessels as well as retrofitted on older boats. In fact, more than 25% of the systems sold are retrofits, some 1,000 in all to date. Typical installations take about two days.
 
Seakeeper makes systems for both recreational and commercial vessels. The recreational line starts with a unit designed for 27-32 foot boats priced at $22,700 and tops out with a system for boats 85 feet and over for $216,300. Commercial units start at $45,900 for 35-41 foot vessels and work their way up to $216,300 for boats 75 feet and larger. Prices do not include installation.

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Page 1 of 3 ( 13 comments)

 
Jp:(8/11/2018 5:28:29 PM) "I have a 2018 Yamaha f40 la and Humminbird helix 7 di , I would like to leverage the nema 2000 capability of the helix 7 to display engine info, what do I need , Humminbird does have a gateway and lowrance makes a Yamaha nema cable, but I'm reading connectors are proprietary . How can I get what is needed?

Joe,
Since these products are not NMEA 2000 certified there is little assurance that they will share data with each other.

1. Here is the link to see all NMEA 2000 certified products: https://www.nmea.org/content/nmea_standards/certified_produ.asp

2. The NMEA 2000 cables and connectors are from many manufacturers: Here is the link for approved cables and connector manufacturers:
http://www.nmea.org/Assets/20180227%20%20nmea%202000%20approved%20cables%20and%20connectors%20table.pdf


"
 
 
AC/DC grounding distance:(8/2/2018 1:29:35 AM) "What about the grounding points of AC /DC systems? can they be grounded at the same point?
If one system has both AC and DC can they both be grounded to a common buss-bar that has only one conection to the hull?

Toby,
Here's what Ed Sherman, electric tech guru at the American Boat & Yacht Council, said:

The ultimate goal should always be to tie ac and dc grounds together on board at a single point. In ABYC Standard E-11, it is described as “the engine negative terminal or its buss.” It is most commonly done at a buss."
 
 
Hard-Over with Brushed APilot Pump:(12/18/2017 5:37:05 PM) "Jim.
What do you mean by ...."Garmin GHP 20 with SmartPump...Because it is a brushless system, it is fail-safe and won’t execute a hard-over turn the way a brushed pump can."


John,
Thanks for the note. Since the description came from Garmin I contacted the company for an explanation. Here's what one of their engineers told me:

On brushed DC actuators, a single-point failure in the drive circuit (shorted wire or blown component inside the controller) could cause the motor to run full speed in one direction and take the rudder all the way to one rail. A brushless actuator relies on timing-controlled commutation, so a short or component fail would cause the actuator to stop moving rather than moving at full speed.


Hope this helps,

Jim"
 
 
trawlerdeejay:(10/13/2017 3:46:51 PM) "Excellent article. I had no idea what the differences were between o183 and 2000, Thank you so much."
 
 
Darryl:(3/27/2017 10:17:15 PM) "Putting the MSRP with each unit reviewed would have been helpful. If each unit was actually tested, the reports on each unit would have been helpful too.


Thanks Darryl---we generally don't mention prices due to confusion over so many variations---MSRP (mfg. suggested retail price), MAP (min. advertised price), MRP (min. resale price) and then there are internet prices on some websites that go their own way. But your point is well taken--buyers need to know if something is in their price range. We'll work on it.
There is independent testing of some of these products on sites like panbo.com but the information we receive from manufacturers rarely cites the results of any shootouts they may conduct against the competition's products. "
 
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