Seakeeper 26 User manual

Rev 7 MAR 2021
OPERATION MANUAL
*THIS MANUAL ALSO COVERS THE SEAKEEPER 20HD MODEL*

OPERATION
MANUAL
Product:
Document #:
Rev:
SEAKEEPER 26 / 20HD
90266
7
SEAKEEPER 26 / 20HD
OPERATION MANUAL
MARCH 2021
Contents:
Section 1 –System Overview
Section 2 –System Operation
Section 3 –Power Failures, Alarms, and Troubleshooting
Section 4 –Maintenance
Section 5 –Warranty, Limit of Liability, Property Rights
Section 6 –Specs and Summary
45310 ABELL HOUSE LANE, SUITE 350
CALIFORNIA, MD 20619, U.S.A.
PHONE: [phone]
FAX: [phone]
E-MAIL: [e-mail]

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Section 1: SYSTEM OVERVIEW
1.0 System Overview
The Seakeeper 26 uses gyroscopic principles to reduce boat roll motions in waves and wakes
independent of boat speed. In multiple Seakeeper installations, the Seakeepers operate
independently of each other and therefore this manual only discusses operation of a single unit.
A Seakeeper 26 consists of a gyroscope assembly, a CAN communications cable, and a Display.
Figure 1 illustrates the interconnection of these components and their interface with the boat.
FIGURE 1 –SEAKEEPER 26 STABILIZATION SYSTEM COMPONENTS
Technical specifications provided in Section 6 list the power consumption, total weight, and
dimensions of the major components. Gyroscopic principals that apply to boat roll control are
discussed on Seakeeper’s web site at www.seakeeper.com. The Seakeeper web site also
contains videos of Seakeeper operation and videos of several different boats operating in waves
with the Seakeeper on and off. It is recommended that the reader play these videos prior to
reading the remainder of this manual.

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Section 1: SYSTEM OVERVIEW
The gimbal angle and the rate of rotation about the gimbal axis (termed precession rate) play an
important role in its operation. These parameters are illustrated in Figure 2. At zero degree
gimbal angle, the sphere is vertical; it can precess a maximum of +/- 60 degrees about this
position. The amount of torque that the Seakeeper exerts on a boat’s hull to counter the wave
induced roll is directly proportional to the precession rate. The further the Seakeeper is from
vertical (zero degrees) the lower the anti-roll torque. The vertical arrows in Figure 2 illustrate the
direction of the forces that the Seakeeper exerts on the boat’s hull to damp roll motion.
FIGURE 2 –SEAKEEPER PRECESSION
Seakeeper precession is actively controlled by an electronic controller and a hydraulic brake
throughout each roll cycle so the Seakeeper supplies the maximum anti-roll torque and does not
make mechanical contact with hard stops that limit the maximum gimbal angle travel to +/- 60o.

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Section 1: SYSTEM OVERVIEW
There is a large torque about the gimbal axis when the Seakeeper is
precessing. Seakeeper cover panels are provided to prevent personnel or
equipment from contacting the Seakeeper while it is in operation. These
covers should not be stood on or have anything placed on top. The covers
should always be in place during operation. If it is ever necessary to touch
the Seakeeper while the flywheel is spinning, the Seakeeper must be
locked at the display to stop the Seakeeper from precessing. Seakeeper
maintenance should not be attempted unless the Seakeeper is locked and
the flywheel has stopped spinning.

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Section 1: SYSTEM OVERVIEW
1.1 Seakeeper Assembly
The Seakeeper assembly consists of a flywheel housed in a cast aluminum vacuum-tight
enclosure. The flywheel spins about a vertical axis and is supported by upper and lower pairs of
bearings. A Permanent Magnet AC motor mounted inside the enclosure spins the flywheel at
high speed.
The enclosure is fastened to two gimbal shafts that are supported by gimbal bearings on either
side. These shafts establish an athwart ship gimbal axis about which the flywheel and enclosure
precess or rotate up to +/- 60 degrees during operation. The gimbal bearings are supported by a
foundation which is attached to the hull structure. This foundation transfers the loads that the
Seakeeper produces to the hull structure.
An active hydraulic brake mechanism is located on the Seakeeper assembly to regulate the
Seakeeper’s precession motions about the gimbal shaft. It includes four hydraulic cylinders and
a hydraulic manifold.
A coolant pump, heat exchanger with reservoir, and thermostat are located near the manifold. A
glycol/water mix is circulated through a closed loop to the motor drive box, hydraulic manifold,
and the water jackets of the flywheel enclosure to remove heat.
FIGURE 3 –SEAKEEPER ASSEMBLY

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Section 1: SYSTEM OVERVIEW
1.2 Display
The display shown below is the user interface to the Seakeeper 26 and should be mounted at
the primary helm station, unless the vessel has compatible Multi-Function Display, in which
case the Seakeeper Display can be mounted elsewhere. It is used to start, operate, monitor and
shutdown the Seakeeper. Sensors, alarms, and shutdowns are provided to allow unattended
operation.
The display provides information in the event of an alarm. Alarms cause precession to stop
(Stabilize Off) and the Seakeeper to start coasting down (Power Off).
FIGURE 4 –OPERATOR DISPLAY

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Section 1: SYSTEM OVERVIEW
1.3 Drive Box
The glycol/water mix that cools the Seakeeper is also circulated through a cold plate inside the
Drive Box to remove heat from high-power electronic components.
The Motor Drive Box contains hazardous voltage. The cover
should not be removed while the flywheel is spinning and the
AC input voltage is present. This high voltage exists even if the
flywheel is coasting down and the supply voltage has been
shut off. The flywheel must be at Zero (0000) RPM and AC input
power disconnected for at least 10 minutes prior to any service
work on the motor drive box.
FIGURE 5 –DRIVE BOX

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Section 1: SYSTEM OVERVIEW
1.4 Electronic Control Module
The Electronic Control Module (ECM) monitors all the system sensors and automatically regulates
operation of the Seakeeper.
The controller commands the motor speed and regulates the Seakeeper’s precession rate and
gimbal angle. This is accomplished by commands to a high response flow control valve in the
hydraulic brake circuit that increases or decreases the brake pressure.
1.5 Inertia Measurement Unit (IMU)
The motion sensor suite in the IMU measures the angular movements of the vessel and the
vertical and lateral boat movement. These signals are communicated to the ECM through the
Seakeeper’s wire harness.
1.6 Brake
The brake mechanism consists of four hydraulic cylinders that attach to crank arms on the gimbal
shafts. The Seakeeper controller modulates how fast the oil can flow through the control valve
thus controlling the precession rate of the Seakeeper.
The brake hydraulic circuit is a pre-charged closed loop system –that is, there is no pump, motor,
or reservoir in the circuit. Accumulators are installed in the circuit so the pre-charge pressure
does not increase as the fluid temperature rises due to the braking action. Locking solenoids are
installed in the circuit to lock the Seakeeper so it cannot precess if there is a leak in the circuit or
a mechanical problem with the Seakeeper.
Seakeeper Hydraulic Hand Pump Kit, P/N 10384, is required for servicing the brake system.
Pressure should never be relieved unless this tool is available.
FIGURE 6 –BRAKE SYSTEM COMPONENTS

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Section 1: SYSTEM OVERVIEW
1.7 Cooling
The cooling circuit is a closed loop that supplies a glycol/water (50% distilled water and 50%
glycol) mix to:
•The motor drive box to remove heat from the drive electronics
•The brake manifold to remove heat from the brake hydraulic circuit
•The flywheel enclosure water jackets to remove heat from the flywheel bearings
The heated fluid then passes through a thermostat before bypassing or flowing through a heat
exchanger that has sea water on the cold side. The circuit also contains a coolant reservoir for
coolant expansion and to make filling easy. The reservoir contains a 7 psi (0.5 bar) pressure cap.
The heat exchanger contains zinc anodes that must be inspected and changed regularly to ensure
maximum heat exchanger life.
FIGURE 7 –COOLING SYSTEM COMPONENTS

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Section 2: SYSTEM OPERATION
2.0 Introduction
This section describes operation of the Seakeeper 26 system.
2.1 Display Screens: Overview
1) When 24 VDC is applied to the Seakeeper the DISPLAY will power up and initialize. The
SPLASH screen will be displayed.
2) After the DISPLAY has initialized the HOME screen will be displayed.

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3) The display uses a touch screen to allow users to select functions.
POWER button: The button will change from grey (Power Off) to blue (Power On).
STABILIZE button: The button will change from grey (Stabilize Off) to blue
(Stabilize On).
Home screen view. These buttons toggle home screen between the Roll Angle
Gauge and the Roll Angle Graph as shown below.

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Section 2: SYSTEM OPERATION
4) When the MENU button is pressed, the menu bar will appear or disappear at the bottom
of the screen.
The menu bar is used to navigate between pages. From left to right, the available pages
are home, settings, information, service, and alarm history. The selected page is
highlighted in blue on the menu bar.

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5) The settings page allows the user to adjust the following:
Increase or decrease the brightness of the display with the brightness slider.
Adjust the sleep timer from 1 minutes to 60 minutes or on all the time using sleep time
slider. Touching the screen will wake the display up after it has gone to sleep.
Change the sign of the roll angle value displayed in the roll angle gauge so the gauge
matches the motion of the boat. This will depend on installation orientation and will only
need to be adjusted once.
Seakeeper facing rear Seakeeper facing forward

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Change the speed of the Seakeeper between normal operation and low power operation.
Low power mode consumes less power and should generate less noise. The selected
speed is colored blue. When power is cycled (or Seakeeper turned Off), this speed will
default back to the normal operating speed. Speed selection buttons shown below are
examples and may not match operating speed of installed Seakeeper.
Change the display between day and night mode. The selected mode is colored blue.
Change the units of the temperatures displayed on the service page between degrees Celsius
and degrees Fahrenheit. The selected units are colored blue.
6) The information page displays the Seakeeper model, Seakeeper serial number,
Seakeeper software versions, RUN hours, and SEA hours, and other information.

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7) The service page displays operating information from the Seakeeper.
8) The alarm history page shows what alarms have occurred in the past and the
associated run hours. The scroll bar is used to move up and down through the list.
2.2 Start-up
1) Energize AC and DC power supplies.
2) Turn on the boat’s DC circuit breaker that supplies power to the Seakeeper.
3) Turn on the boat’s AC circuit breaker that supplies power to the Seakeeper.
4) In most cases, the seawater pump will be wired directly to the Seakeeper and turn on
when the Seakeeper is turned on. However, in some cases the seawater pump is on a
separate AC or DC circuit breaker and it is necessary to turn it on.
5) When the DC power is turned on the DISPLAY will initialize and the HOME screen will
appear. If a FAULT is present an ALARM screen will appear.

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To turn the Seakeeper on, press the POWER button; the button will turn blue. The
progress bar will appear and indicate how soon the Seakeeper will be available for
stabilization. When the Seakeeper is initialized and up to minimum operating speed the
STABILIZE button will appear. At this point, the Seakeeper is available for stabilization.
6) When the Seakeeper reaches its maximum operating speed where maximum stabilization
is available, the progress bar will disappear and the Seakeeper is available for maximum
stabilization.

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Section 2: SYSTEM OPERATION
2.3 Stabilization
To stabilize the boat after Seakeeper is on and above the minimum operating speed:
1) Press the STABILIZE button. The button will turn blue indicating that the Seakeeper is
stabilizing the roll motion. The stabilization mode starts gradually; it takes 5-10 seconds
to reach full effectiveness.
If it is necessary to shutoff power to the flywheel motor
and slow the flywheel for any reason, press the
Seakeeper POWER button; the button will turn grey and
the stabilize button will disappear indicating the
command has been accepted. It takes approximately 6+
hours for the speed to drop to zero rpm.
If it is necessary to stop Seakeeper motion for any reason
press the STABILIZE button. The stabilize button will turn
grey indicating that the Seakeeper is locked. Never
attempt to work on the Seakeeper until the flywheel has
stopped spinning. If the brake system has automatically
locked the Seakeeper due to an alarm or failure, no
attempt should be made to bypass the alarm or automatic
lock.
!
!

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Section 2: SYSTEM OPERATION
2.4 Normal Shut-Down
The Seakeeper should be stopped when pulling into port and stabilization is no longer
required. This maximizes life by allowing the Seakeeper to start the coast down cycle
before cooling is shutoff. Once the vessel is secured, the AC and DC breakers can be
switched OFF. The Seakeeper will continue to spool down to zero rpm. No cooling is
required during this time.
Note: The seawater pump may run for 5 minutes after the Seakeeper is switched off and
is coasting (with AC power applied).
1) Press the Seakeeper POWER button. The POWER button will turn grey. The Seakeeper
will start coasting.
2) Once the vessel is secured in the slip and the crew has shut down the generator and
engines, switch the AC and DC breakers that control the Seakeeper OFF. The flywheel
will continue to spool down to zero rpm. This can take 6+ hours from full speed.
When the flywheel has stopped spinning 0 RPM will appear on the screen

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Section 2: SYSTEM OPERATION
The circuit breakers should be left on as long as possible
while the Seakeeper is spinning to remove heat from the
Seakeeper. During normal operation, the Seakeeper
should be stopped when pulling into port and stabilization
is no longer required. This maximizes long term life as it
allows the Seakeeper to start the coast down cycle before
cooling is shutoff. Once the vessel is secured in the slip
and the crew has shut down the generator and engines, the
AC and DC breakers that control the Seakeeper should be
switched to the OFF position. The Seakeeper will continue
to spool down to zero rpm. No cooling is required during
this time. Note Seakeeper 26 will take approximately 6+
hours to coast down to zero rpm from full speed. The
Display will indicate 0 RPM when the flywheel has stopped.
Note: The seawater pump may run for 5 minutes after the
Seakeeper is switched off and is coasting (with AC power
applied).
!