The boat can move up and down, side to side, and forward and aft in the direction of each axis. It can also swing or rotate on each axis. Two motions per axis equals six motions total: surge, roll, pitch, sway, heave, and yaw. Another big factor is sway, the side-to-side motion. If you can reduce the degree and acceleration of the roll, you can go a long way towards reducing the incidence of seasickness. For example, a narrow, round-bottom boat e.
You might think the flat-bottom boat would be more stable, and in smooth water, it is, but that also means it will hug the surface of the wave more readily in longer waves and that makes it harder to stabilize. By comparison, the narrower, rounder shape typically will be easier to stabilize. Note these are general rules, and the bottom line is that the boat will roll the most when the natural roll period of the boat is equal to the roll period of the wave. In this scenario, the momentum of the rolling boat causes it to continue to roll even as the wave passes, thus creating the greatest degree of roll.
Eventually, the boat will stabilize somewhat until the cycle starts anew. No stabilizer system will counteract some of these motions, particularly heave and to an extent, pitch. But Vector Fins in particular can make a big difference in yaw, roll and sway, which is good, since those last two are the two motions most likely to cause seasickness.
Because gyros do not have an appendage in the water, they do not influence sway and yaw. The gyro stabilizer is essentially a large, heavy spinning disc, turning at very high rpms, sort of like a throwing wheel used to make a clay pot. As the boat rolls, the spinning wheel naturally angles forward or aft, imparting a force on the hull in opposition to the roll. As a series of waves tries to roll the boat, the gyro constantly tilts forward or aft, within the limits of the hydraulic cylinders controlling it.
If you have ever stuck your arm out of the car window on the highway, you know that angling your flat hand will cause your arm to go up or down depending on which direction you rotate your hand. The fins moving through the water basically create the same effect. This is the time it takes for a boat to roll to one side, then other, and then back to center.
It also happens to be the natural roll period of most motor yachts in the range of about 55 to 90 feet, so stabilizers become particularly useful on these yachts.
Of course, stabilizers will control unwanted boat roll on any size boat. Vacuum Encapsulation The vacuum containment enables us to spin the flywheel three times faster, cut its weight by two-thirds, and halve the power requirements.
Is the vacuum necessary? Active Control Every Seakeeper has a hydraulic braking system and active control, smart technology that automatically gauges the sea state and reacts instantaneously. Are air-cooled systems better? Why would I need more than one Seakeeper? Follow Seakeeper for Updates Get on the list to receive updates about new Seakeeper products, exclusive sales and more.
First Name. Last Name. The increased mass does represent a hull drag cost, however when compared to the drag of inefficient low aspect ratio zero speed fins especially if they are actually working , a significant net reduction in drag is achieved. No Risk of Grounding Damage — We have all experienced or heard stories of stabilizing fins being damaged by collision with floating debris, or grounding.
This usually results in time consuming and expensive dry-docking for repair of replacement. This is simply not possible with a gyrostabilizer located inside the hull. No Fouling with Nets or Cables — The risk of fouling fishing nets, long lines, buoy anchors, or cables is removed completely with a gyrostabilizer located inside the hull.
No Equipment Outside of the Engine Room — By locating the gyrostabilizer s in the engine room, noise levels are reduced as compared to fins most important at night , and there is no requirement for technical personnel to enter the owners spaces for operational or maintenance tasks related to fins. No Dry-Docking for Maintenance, Ever — Dry-docking is a hectic and crammed period, with many systems requiring attention.
So take a few lines off the docking list by selecting a gyro over fins. Having the gyro delivered as a fully self-contained item of equipment saves a vast amount of time, effort and money coordinating frame penetrations, cable runs and piping runs through the hull.
As a relatively new product, there are still several myths about Gyrostabilizers that we wanted to clear up. In fact, just as important is the way in which precession motion is controlled.
The major considerations that define the performance of a gyr stabilizer are: flywheel angular momentum, the precession range allowed, the maximum precession rate allowed, and the ability of the gyrostabilizer to maintain full precession range when vessel rolling rates are low.
All of these considerations are handled differently by the various vendors of gyro stabilizers. Understanding exactly how each unit works will allow the most informed selection of the best gyrostabilizer system for your application. A good place to start is to find out exactly how much stabilizing torque is generated across a range of rolling periods.
This will unearth many of the considerations discussed above. It is also very important to understand what the operational envelope of the gyrostabilizer is.
Will the unit continue to operate in rough conditions when you need it most? In what conditions if any will the unit shut down or de-rate to protect itself? This is theoretically possible, but not a practical reality. The resulting uncomfortable harmonics introduced into the rolling motions of the yacht would create a significantly less comfortable experience for those on-board. Given that there is a finite range of precession available before the stabilization torque starts to increase rolling motion, if you accelerate precession motion through some of that range then you need to decelerate this motion somewhere else in the cycle.
So while it theoretically possible to do this, it is not a practical solution. If it sounds too good to be true…then it probably is. In fact, in very small waves where the gyrostabilizer is not overpowered, a vertical axis gyrostabilizer could work without any control system whatsoever.
A horizontal axis gyrostabilizer would also work a little, but the very high resistance to precession of the slew ring bearings used on these systems would significantly limit the stabilizing torque generated. Stabilization torque is not caused by the precession axis braking torque, it is caused by the precession oscillation rate combining with the angular momentum of the flywheel to generate torque in the roll axis.
The precession braking is only applied to manage the precession motion to within a nominated precession oscillation range and in most cases also to limit the rate of precession oscillation so that the gyrostabilizer torque created is effectively capped allowing the supporting structure to be designed to withstand a defined maximum level of load.
Because a gyrostabilizer produces a pure torque, it can theoretically be located anywhere on the vessel. The stabilizing torque will always neatly oppose the rolling torque whether on or off vessel centre-line, or whether forward or aft.
To avoid high vertical accelerations that might shorten the life of the bearings, VEEM recommends that the unit s are located aft of mid-ships. So long as the overall mass distribution of the vessel is maintained, there is absolutely no performance disadvantage to locating the gyrostabilizer s off centerline.
If the gyrostabilizer s are located more than 2m above the waterline, please discuss this with VEEM. The flexible rubber isolation mounts may need to be transversely supported to prevent over-load.
In most cases, the convenience of electrical power supply and suitably strong supporting structure will result in the gyrostabilizer being located within the engine room. This has the added advantage of enclosing the gyrostabilizer within a noise lagged space. Where the gyrostabilizer s are located outside of the engine room, noise isolation considerations should be addressed.
This helps to eliminate annoying night-time noise, and to ensure that service technicians do not need access to the owners spaces. In fact, a pre gyrostabilizer invention claimed to work without precession. This was eventually debunked and the invention discredited. If the flywheel does not precess, no stabilization torque is generated. This is how a gyrostabilizer can be turned OFF without stopping the flywheel from spinning.
The precession oscillation axis is simply locked. In fact a spinning flywheel does not have any inherent stability, or tendency to remain at its current orientation.
This is this basis of inertial navigation systems INS. In an INS, sensors on the gimbals' axles detect when the platform rotates. The INS uses those signals to understand the vehicle's rotations relative to the platform. If you add to the platform a set of three sensitive accelerometers , you can tell exactly where the vehicle is heading and how its motion is changing in all three directions.
With this information, an airplane's autopilot can keep the plane on course, and a rocket's guidance system can insert the rocket into a desired orbit! Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe.
How Gyroscopes Work. Precession " ". Click here to download the second full-motion video showing precession at work. In figure 1, the gyroscope is spinning on its axis. In figure 2, a force is applied to try to rotate the spin axis.
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