By Gary Caputi
Seakeeper gyrostabilizers have revolutionized the boating industry. The story of how beneficial Seakeepers can be for those who use them has been widely told. How they are made and exactly how they work, however, is as fascinating as the results they produce.
At its most basic level, a Seakeeper works by creating torque through rapidly spinning a flywheel inside of its housing. The force of the torque is then transferred to the hull of the boat. The force of this application keeps the boat steady, even as it would otherwise roll with wave action.
Here is the expert breakdown: How Seakeepers Work Andrew Semprevivo, Seakeeper’s President and CEO, provides some context as to how Seakeeper units reduce the roll of the boat on the ocean.
“A gyroscopic stabilizer is the most unintuitive technology you could imagine, but that is the magic of it. Something so small, quiet, and completely internal of the hull is creating such a great impact,” he said as we got into the operational dynamics of the system.
He explained that the concept was not new and showed me pictures of a ship with two massive ball-shaped gyros from way back in 1905. The systems fell in and out of favor in the shipping industry because they were so large and heavy, but the basic principles were the same.
A Seakeeper is composed of a heavy flywheel that spins horizontally at a high rate of speed inside of a ball-shaped housing. To achieve its desired result, a Seakeeper applies torque created by the rapid spin of the flywheel using the angular momentum. Angular momentum represents to gyroscopes the equivalent of what horsepower is for an engine.
Angular momentum is the product of the flywheel mass, flywheel diameter, and how fast the flywheel is spinning (angular velocity, technically speaking). It is the angular momentum of the unit that will determine the amount of torque available over time.
The faster the gyro tilts (precesses), the higher the peak torque that is available. Instantaneous peak torque, however, would not be the most effective use of the gyro’s angular momentum. To understand why requires a bit of a physics lesson. Ocean waves are not single bursts of energy. Rather, waves apply force to the boat sinusoidally (in a wave-like manner) over a period of three to seven seconds.
Seakeeper uses its active control system to apply the force of the gyro to the boat in the most effective way possible. Seakeepers precisely apply torque to counter the sinusoidal application
of the wave force over the course of this three to seven-second period. Simply stated, as waves try to force the boat to roll, Seakeepers apply torque precisely when it best impedes the movement.
The torque created by the flywheel tilting (precessing) fore and aft is then applied to the transverse axis of the boat to dampen movement caused by wave action. The effect of the torque applied precisely in line with the transverse axis of the boat results in the elimination of roll.
If you’ve ever played with one of those toy gyroscopes, you’ve experienced precession. When you hold the spinning toy still you don’t feel any pressure being applied to your hand, but as soon as you begin turning it you can feel it apply force dampening against the movement.
Seakeeper has developed a sophisticated, active control system that combines motion sensors with a computer module that gauges the roll rate of the hull. The Seakeeper then uses its hydraulic braking system to dampen the precession rate and inertia generated by the spinning gyro. The effect of this system is to match the precession (tilt) of the unit to the roll rate of the boat on the waves.
The active control of precession is why you can stop the effects of the unit by locking it in a standby position, even as the flywheel is still spinning at thousands of revolutions per minute. This active control system is also why the Seakeeper can be used in any sea state, at any speed, without the need for manual adjustments. The computer automatically senses any change in conditions and instantaneously adjusts the gyro’s precession with the hydraulic brakes to optimize the torque output with every roll cycle.
How a Seakeeper is Made
The technology that goes into manufacturing a Seakeeper is nothing short of remarkable. The equipment housed in their facility and the expertise of the machinists and technicians that operate the dozens of high-tech milling, balancing and testing machines is on a level commensurate with companies in the aerospace industry building components for fighter jets and the space shuttle.
The heart of the unit is the flywheel. To spin it at such high speeds, 9,750 RPM in some models, requires machining a single massive steel forging. The gyro’s components are ground to tolerances of 1/10,000th of an inch. To put this into perspective, that is roughly 1/3 the diameter of a strand of hair. This level of minute tolerances can only be achieved in a temperature-controlled environment.
Even a few degrees variance can cause expansion or contraction which could alter vital component fit. There are very few “off the shelf” parts available for such an intricate build. The ceramic bearings the flywheel spins on are purpose-built for Seakeeper. Even the lubricants require special properties, so they won’t disperse while operating in a vacuum. The balancing of the flywheel is critical, so the units run smoothly and do not impart vibrations to the boat.
The precision involved became evident when I placed my hand on the flywheel housing of a Seakeeper 26 spinning at 5,000 RPM on a test platform. The movement was almost imperceptible and it was so quiet I had to be told it was actually running. Now that’s precision!
When Seakeeper first went into production almost every component was machined in house. As unit production increased, the company has contracted specialty manufacturers to cast and perform initial machining of certain parts and subassemblies. Today, all of the finishing and assembly is carried out in house to maintain the critical tolerances required and assure overall quality control.
Once the flywheel and housing are complete, the assembly process begins with the installation of the ceramic bearings and the proprietary glycol cooling system components. The housing, consisting of two halves, is reassembled with the flywheel in place. The unit then moves to a test platform where the flywheel is spooled up for an initial run-in period. This ramp up period is critical to evenly dispersing the special bearing grease.
The entire assembly undergoes a second balancing process that uses laser measuring devices to detect even minute vibrations. The housing is then fully sealed and the air is removed, creating a vacuum. The unit is pumped down to zero torr, then backfilled to 10 torr of helium (a Torr is a unit of measure that describes pressure).
Seakeeper units are filled with helium because of its thermal conductivity properties. Together these processes—run-in, creating the vacuum, and baking out the excess grease—take upwards of ten
hours to complete on each unit. That doesn’t even include machining, assembly, or testing.
Upon assembly and testing, the flywheel enclosure is mated to the unit frame and the final assembly process is underway. This stage includes the assembly and integration of the hydraulic brake, motor drive, computer control box, cooling system and wiring harnesses.
The finished Seakeeper then undergoes a series of grueling quality control tests. These tests, designed to measure the unit’s response and effectiveness, include a five-hour stint on a hydraulic tilt table that simulates real world, on board operation. Only after satisfying all of these requirements is a finished Seakeeper crated and prepped for shipping.
The Line Up
With the introduction of the diminutive Seakeeper 1, Seakeeper now offers 10 models that cover the recreational boat market from 23-feet to greater than 85-feet with displacements up to 100 tons. Larger vessels, and those without space for one unit, can be accommodated with multi-unit installations.
Each unit is designed to provide the ideal amount of angular momentum at the rated RPM to impart the necessary torque required to arrest roll for the prescribed vessel size range. All Seakeeper units are designed to reduce vessel roll by up to 95 percent.
The Seakeeper 1, launched in February of 2020, is designed for boats from 20 to 23 feet in length with displacements of up to 5.5 tons. tons. At just 365 lbs., the new Seakeeper 1 features a flush
mount design for easier installation, runs exclusively on 12V DC power, and can be installed virtually anywhere on board.
Do you have any comments or questions for us? We’d love to hear from you.
By Steve Katz
It’s often an emergency that prompts a look at a boat’s steering system. While routine maintenance of modern steering systems is usually simple, an at sea steering issue can quickly and easily result in rudderless steering and an oily bilge! While I have witnessed many captains maneuver a boat with amazing skill using just the engines, having a properly operating steering system is prudent and allows safe operation in all conditions.
What type of steering system do you have? While most sportfish crew would answer hydraulic, there are many variables today that differentiate the design, components and operation of a vessel’s steering system. Learning about your boat’s system can assist when it comes time for maintenance, ordering repair parts and performing bleeding (more about this later).
Steering Systems of Old – And their Modern Counterparts
Some readers may remember the cable and pulley steering systems on sportfish boats of the past. This system was complete with cables and pulleys neatly hidden under the headliner and jackshafts, with more pulleys and cables, transferring the steering power to the rudders.
Most of these mechanical systems have gone the way of the dinosaur – replaced with a variety of hydraulic solutions on sportfish boats. Hydraulic systems provide better command of the vessel’s directional stability and result in less fatigue on the captain.
At its most basic level, a hydraulic steering system consists of a helm pump, steering cylinder, rudder(s) and interconnecting hoses. The helm pump is a hydraulic pump attached under the helm wheel.
When the helm wheel is turned, the helm pump pushes hydraulic oil through the hydraulic fluid lines and into the cylinder that pushes the internal piston one direction or the other, depending which way you turn the helm wheel. While most steering systems on sportfish boats are more complex with additional components, the operating principal is the same.
Steering systems are designed with many considerations in mind. These factors include: the size, weight and speed of the vessel, how the vessel is used, and the design and location of the rudder.
Physics and fluid mechanics provide the basis for the design of these systems. Luckily, most marine steering companies and boat manufacturers will perform the necessary calculations to recommend various steering solutions for your specific vessels requirements. Thankfully, you can leave your calculators and physics workbooks at home.
Steering System Maintenance
No matter what steering system your boat has, there are two common components to all systems: the hydraulic oil and cylinders. The most critical part of any hydraulic system is clean hydraulic oil. Many times, we hear about the need to bleed a steering system. The need is often caused by a leak in the system that let air or water into the system, while letting oil out.
A boat’s hydraulic steering is a closed system that operates on high pressures of 1000 PSI or more. At these pressures, even a slight leak from a hose or seal will quickly cause oil to leak out. This can possibly disable the steering system.
Each steering system manufacturer offers specific procedures for filling and bleeding of their systems. The basic premise for bleeding is to circulate clean hydraulic oil through the system while bleeding the air out until a steady stream of air and contaminant free oil is observed.
EPS systems often have a maintenance mode that may be accessed through the steering control display. Maintenance mode will walk you through the procedure for bleeding the system.
Varieties of Steering Systems in Sportfishing Boats – Description and Application
Cars, trucks and off-road machinery all have power steering, so why isn’t power steering as common on the sportfish market? Marine steering system manufacturers have made it easy to have safe and reliable marine power steering systems. Such systems provide precise steering from the helm, reducing operator fatigue and increasing steering accuracy at both low and high speeds.
The most common power steering system uses an engine-driven hydraulic pump to provide high pressure hydraulic oil for the power circuit of the steering system.
A marine power steering system adds a second hydraulic cylinder and second hydraulic oil circuit from the engine-driven pump. The high-pressure power circuit is actuated by the manual system from the helm wheel.
This is accomplished using a small servo cylinder/valve mounted on or near the steering cylinder. This cylinder/valve directs the power steering oil to the power cylinder when the helm wheel is turned. The nice feature of this system is that if the power steering circuit fails, the traditional manual steering at the helm can still function – though more force is often needed with more wheel turns lock-to-lock.
Electric Power Steering Pumps
This type of hydraulic steering operates similarly to the engine-driven power steering system, but without the engine driven pump. The hydraulic power comes from a standalone electric motor, usually supplied with DC power. These systems vary in design. While their primary application lies with large center console boats powered by multiple outboards, electric power steering pumps are becoming more popular in sportfish boats.
There are two design styles of electric power steering systems – one with a constantly running electric hydraulic pump and the other with an on-demand electric motor pump. While the end result is similar, the feel of the system and response time is slightly different.
Most of the large sportfish boats that use electric power steering include the constantly running engine, while the on-demand pumps system is often used in center console boats.
The constantly running pump system supplies high pressure hydraulic steering oil to the steering system continuously while the steering system is powered on. Contrarily, the demand system pump is always off, until the captain begins to turn the helm wheel, which triggers a sensor in the hydraulic system that turns on the pumps motor.
The on-demand system uses less electricity and helps reduce the steering effort as compared to manual steering, though the feel and reaction time is much different that and constant running pump.
Steer by Wire – Electronic Power Steering (EPS)
Electronic controls are not just for the engines anymore. Today’s electronic steering systems operate in a similar fashion to the electronic engine controls that run the vessel’s engines and marine gear. These steering systems are often called Electronic Power Steering or EPS.
In an EPS system, the helm wheel is connected to an electronic sensor instead of a hydraulic helm pump. Digital data signals are sent along wires to the steering system below deck, usually consisting of a computer processor, electric pump(s) and steering cylinder(s) that are connected to the rudders.
The most popular form of EPS is the Seastar Optimus system for outboards. This system consists of independent pumps and cylinders for each outboard engine. As you might imagine, a computer system controls the coordination of each outboard engine relative to the others. When the captain turns the helm wheel, the signals travel into the computer and then to each electric pump and engine cylinder.
This set up enables some amazing features that are unavailable with any other steering systems. An EPS system can be programmed to decrease the number of helm wheel turns lock-to-lock for ease of low speed maneuverability.
An EPS can also increase the lock-to-lock turns at high speed to improve stability, tracking and course keeping. The steering angles can also be customized based on the boat’s performance and speed curves.
Another feature of EPS systems is that the large hydraulic steering lines are replaced with small wires connected to each helm wheel. This makes adding a second or third steering station a much simpler task – as compared to routing bulky hydraulic lines. The new EPS systems are designed for both new construction and retrofit projects to replace traditional steering systems.
While a joystick was once reserved for steering Pac Man, the EPS steering system enables joystick control of outboard vessels at low speeds. Joystick control is possible in conjunction with digital fly by wire engine controls. This set up allows the joystick control to change the engine rpm, engine gear direction and engine steering angle. These joysticks steering for outboards are similar to the vectored thrust systems used in the Volvo Penta and ZF pod systems on sportfish boats.
Not just for outboards
The Seastar Optimus EPS system is now also available for inboard boats up to 70’. The Optimus system operates in similar fashion as other electric inboard power steering systems, but is also available in more advanced configurations, depending on the application.
In its simplest form, the electronic power steering system uses an electronic helm, single power steering pump and single cylinder at the rudders. In a more advanced system, there can be one pump and cylinder for each rudder without a tie bar. This allows the rudders to operate independently or in unison, depending on the pre-programmed operating parameters.
Viking Yachts knew an EPS system like this would have many advantages for sportfish boats and designed their own system years ago. The steer-by-wire Viking Independent Proportional Electro-Hydraulic Rudder system is referred to as the VIPER steering system. The VIPER’s rudders are individually controlled with one steering cylinder per rudder. When the helm wheel is turned, an electric signal is sent to a controller whose software dictates the optimum position for each rudder.
Viking can adjust the offset or rudder toe and the number of turns lock to lock by altering the software programming. The system can also be programmed with different parameters based on the vessel’s speed. The Viper system has its own graphic display, showing each rudder position and other steering information.
Whether cruising, docking, fishing or backing down, advancements in steering systems have contributed to the ease and reliability of operating a sportfish boat.
No matter how advanced the system, steering still relies on traditional aspects such as rudder size and shape, properly sized hydraulic cylinders, helm pump, hoses and other components. A regular visual inspection of your steering system components will help you to learn what you have and determine if and when maintenance is needed.
Most autopilot manufacturers offer a system for boats with EPS systems. These autopilot systems are similar to a traditional autopilot system, except for one component – the hydraulic pump. In an EPS system, the autopilot manufacturers substitute a gateway or electronic module for the hydraulic pump. This gateway
electronically connects the autopilot to the vessels steering system, allowing the autopilot to send steering commands to the EPS computer in a similar fashion that the electronic helm wheel would send steering input signals. This autopilot gateway is specific for each type/brand of steering system.
Boats with traditional hydraulic steering use an autopilot system that incorporates a standalone autopilot hydraulic pump connected to the steering system as an additional station. There are a variety of hydraulic pumps available and are selected by capacity based on the volume of the steering cylinders. Don’t guess or select the pump by price as an undersized or oversized autopilot pump can cause unacceptable autopilot performance.
If your boat has a constant running power steering system, you may be able to forgo the need for the traditional autopilot pump. Some autopilots can connect to the existing directional solenoid valves in the power steering system.
A technical note – In regards to the hydraulic portion of the autopilot system the National Marine Electronics Association (NMEA) installation standard 0400, indicates that “Isolation valves shall be installed in the hydraulic lines connected to all ports entering the autopilot pump.”
This allows for isolation, service or replacement of the autopilot hydraulic pump without disturbing the rest of the vessel’s hydraulic steering system. This practice is often overlooked in many boat steering systems.
Autopilots have advanced a long way in just a few years. Most components are shrinking in size and heading sensors are becoming solid state, multi-axis sensors and even using GPS as a basis for heading in place of a fluxgate compass. The advancement has also allowed autopilots to perform better and allow for new interesting features, such as Furuno’s Sabiki mode.
Captain Steve Katz is the owner of Steve’s Marine Service Inc in Ocean City, Maryland. He is the Vice President of the National Marine Manufacturers Association and holds ABYC Master Technician certification, NMEA AMEI, NMEA2000 certificates along with factory training from many manufacturers. To contact Steve, email firstname.lastname@example.org.
Anatomy of a SAR Case: Beware the Bar
As seen in the Coast Guard Mid Atlantic
All is quiet on the pier at Coast Guard Station Oregon Inlet, where two steely boats bob and sway in the shadows. One of the two suddenly roars to life, deck lights blazing and radar antenna twirling.
Five orange-clad figures bustle around on the boat, popping in and out of the compartments, snapping on life jackets. When the boat is deemed ready, they huddle up on the back deck and discuss the plan for this early morning underway trip.
Their objective: conduct a bar report.
Every morning, approximately 30 minutes before sunrise, the station crew heads out to assess the conditions of the Oregon Inlet bar, a sandy shelf that lurks only about 5 feet underwater at the inlet’s entrance. The bar serves as a harsh welcome mat for boats entering the inlet; rushing water collides with the sand bar, rockets up to the ocean’s surface, then spikes in a turbulent pile of breaking waves.
Station Oregon Inlet crews monitor the conditions at the bar, relay the information to local mariners, and help boaters navigate the dangerous strip of whitecaps and waves. It is a recurring part of the crew’s routine; depending on the weather and boat traffic, they often conduct bar reports more than once a day.
At 6:34 a.m., the crew reaches the bar, pleased to see that conditions are considerably mild. Waves arc about 2 feet over the ocean’s surface before dipping back down, tugged along by a strong ebbing current. Winds skim the waves at 10 mph, tossing up a pleasant, 64-degree breeze.
The 2-foot breakers are a welcome sight to the crew, who have experienced upwards of 14-foot waves at the bar. Boat rides are often wild, stomach-dropping roller coaster rides in the inlet, but such is life at a Coast Guard surf station.
The crew hovers near the bar to watch the procession of recreational fishing boats parade by, most of them headed out for a day of angling at the Gulf Stream. They all glide easily through the small waves at the bar, and the Oregon Inlet crew starts entertaining thoughts of breakfast back at the station.
Until, that is, a 60-foot sport fisher crests the bar, then completely stalls.
A flip switches on in coxswain BM2 Travis Porter’s mind. His eyes scan the name stamped on the boat’s stern – Lor-A-Di – and he calls out to its crew on the radio, trying different frequencies. When they don’t respond, he approaches. The Coast Guard crew sidles up alongside the stalled boat, their 47-foot Motor Lifeboat looking quite stalwart beside the sleek, white Lor-A-Di.
Through a shouted conversation, BM2 Porter learns that the vessel’s engines have failed and that the Lor-A-Di is completely dead in the water.
For a brief moment, he observes the vessel crawling south, tugged along by the strong current. He glances at the waves, now building to heights of 4 feet, and makes the call: “Prepare the deck for a stern tow!”
The well-trained crew flies into action, coiling lines and rigging gear. Even SN Nathan Kapsar, now technically participating in his very first search and rescue case, moves without hesitation, unfurling the heavy towline. On Porter’s command, the MLB’s engineer, MK2 Mathieu Desautels, chucks a heaving line to a crewman waiting on the Lor-A-Di’s bow: success in one throw.
Station Oregon Inlet coxswains and crew members practice towing on a regular basis, and on this February morning, it shows. In a matter of minutes, Porter tows the Lor-A-Di over the bar and away from the breaking waves.
Once clear of the whitecaps, the Coast Guard crew detaches the tow and waits nearby while the boaters examine their vessel for damage and try to restart the engines. They rumble to life, but the Lor-A-Di’s captain reports a severe vibration in the propeller shafts. They need to head back to Wanchese Harbor, but they won’t be making the journey alone.
Porter and his crew focus on the new mission at hand: escorting the seven people aboard the Lor-A-Di back to their homeport.
Although it’s only about 10 miles to Wanchese Harbor, the going is slow and the trip takes over an hour. The Station Oregon Inlet crew sees the Lor-A-Di safely moored, then waits for another MLB crew to arrive and relieve them.
This second crew conducts a vessel inspection to check all of the mariners’ safety equipment. The inspection goes smoothly; this was only the Lor-A-Di’s second voyage, and the brand new sport fisher is well-equipped.
Meanwhile, Porter wheels the MLB around and points the bow southeast, where the sun now gleams over the waters of Oregon Inlet. They have already accomplished so much, and all of it before breakfast.
Later, when asked about this case and others like it, Station Oregon Inlet personnel revealed that this is a common occurrence in the area.
“I have been stationed at Oregon Inlet for four years and have been a part of about 50 cases,” said Porter. “The most common case we get here is towing disabled vessels. Oregon Inlet is beautiful, but is a very dynamic and challenging area for mariners.”
“The shoaling conditions change on a daily basis, which is another reason this area is so dangerous,” SN Kapsar added.
When the station crew responds to a disabled vessel, they often find that the culprit is none other than the Oregon Inlet bar.
“We see lots of capsizing, grounding, and damage on the bar,” said Senior Chief Petty Officer Mark Dilenge, the station’s officer in charge. “Even on a flat day, the amount of ocean water that flows in and out creates huge tidal effects, which can be super dangerous.”
Luckily, the crew is not only well-trained to tow vessels around and over the notorious bar, they are also well-equipped.
The 47-foot Motor Lifeboat is the workhorse on which station personnel rely to facilitate these missions, and rightfully so – the robust, aluminum boat is capable of handling much harsher conditions than those the crew experienced on Feb. 23.
In order to avoid being pulled to safety by a 47 MLB, the Station Oregon Inlet crew urges mariners to keep a constant eye on weather forecasts, heed the station’s bar reports, and take time to familiarize themselves with the Army Corps of Engineers’ depth surveys.
After properly outfitting their vessels and preparing themselves for every voyage, boaters should be able to fully enjoy Oregon Inlet and all its charms.
“I love the area,” said Kapsar. “I love how much history the Outer Banks have. The first Surfmen were here, and now I get to be a part of that history, protecting the same coastline they did.”