Seakeeper 18 User manual

December 2019, Revision 1
OPERATION MANUAL
*THIS MANUAL ALSO COVERS THE SEAKEEPER 16 MODEL*
NOTE: THIS APPLIES TO SEAKEEPER 16 MODELS AFTER SERIAL No. 16-201-XXXX or LATER

OPERATION
MANUAL
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SEAKEEPER 16 / 18
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SEAKEEPER 16 / 18
OPERATION MANUAL
DECEMBER 2019
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, MARYLAND, 20619, U.S.A
PHONE: [phone]
E-MAIL: [e-mail]

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Section 1: SYSTEM OVERVIEW
1.0 System Overview
The Seakeeper 16/18 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 16/18 consists of a Gyro assembly, a CAN communications cable (30243 and
30301), and a Display (30298). Figure 1 illustrates the interconnection of these components and
their interface with the boat.
FIGURE 1 –SEAKEEPER 16/18 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 website 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 +/- 70 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 because the torque is exerted
perpendicular to axis of the flywheel. 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 +/- 70o.

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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 DC brushless 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 +/- 70 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 and heat exchanger with reservoir are located near the manifold. A glycol/water
mix is circulated through a closed loop to the motor drive box, hydraulic manifold, and the end
caps 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 16/18 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. However, the Seakeeper is a high-speed machine and special attention should be
paid to abnormal vibration and noise as this could be the first hint of a mechanical problem.
The display provides information in the event of an alarm. Alarms automatically cause precession
to stop (LOCK) and the Seakeeper to start coasting down (STOP).
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 and 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 wiring harness.
1.6 Brake
The brake mechanism consists of four hydraulic cylinders that attach to crank arms on the
Seakeeper gimbal shafts. The Seakeeper controller modulates how fast the oil can flow through
a 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. An accumulator is installed in the circuit, so the pre-charge pressure
does not increase as the fluid temperature rises due to the braking action. Locking solenoid
valves are installed in the circuit to lock the Seakeeper, so it cannot precess if there are any
alarms or a mechanical problem with the Seakeeper.

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Section 1: SYSTEM OVERVIEW
FIGURE 6 –BRAKE SYSTEM COMPONENTS