When selecting stabilization solutions for either a refit or a newbuild project, customers today can choose from a variety of different systems and technologies. The stabilization system can be passive or active, and the most popular include fins and gyroscopes.
PASSIVE AND ACTIVE STABILIZATION
Passive stabilization relies on the design and weight distribution of the boat to naturally stabilize it in the water. This can include features such as a deep keel or a low center of gravity, which help to keep the boat steady. They are a cost-effective and straightforward solution for smaller boats, however, passive stabilization is limited in its effectiveness and may not be enough in rough conditions or for larger vessels.
Active stabilization, on the other hand, uses mechanical devices to actively counteract the forces causing the boat roll. This can include fins, which extend from the hull of the boat and provide resistance to the water, or gyros, which use rapidly spinning weights to stabilize the boat.
MAIN STABILIZERS: FINS VS GYROS
Fins and gyros are the two main types of active stabilizers used in recreational boating. Fin stabilizers are long, narrow blades that extend from the hull of the boat and provide resistance to the water. They work by creating a downward force (generating hydrodynamic forces) on the water, which counteracts the rolling motion of the boat. This helps to keep the boat level and reduce the amount of rocking and rolling that you experience. Fins are typically mounted on the hull of the boat and can be adjusted to provide more or less stabilization depending on the conditions.
Gyro stabilizers use rapidly spinning weights to create a gyroscopic force that counteracts the force of the water pushing against the boat, keeping it stable. Gyros are often installed as part of a boat's design or added as an aftermarket upgrade and require less maintenance than fin stabilizers.
The principle aim of these rival systems is to reduce uncomfortable boat motions, and therefore seasickness, minimising the inconvenience for passengers and crew, but they achieve this common task in very different ways. A gyro stabiliser, such as a Smartgyro, uses a rapidly spinning flywheel mounted on hinged bearings within a spherical enclosure that applies a counteracting force to the boat’s motions. In a Smartgyro, the flywheel spins in a vacuum for additional efficiency, high performance, and reduced heat build-up. A fin stabiliser on the other hand, works outside the hull, like a small aircraft wing that constantly adjusts using sensors and electronic or hydraulic actuators, so that the flow of water over it can create a righting movement.
PROS AND CONS: CHOOSING THE RIGHT STABILIZER FOR YOUR NEEDS
While fins have been the go-to option for many years, they do have some downsides. For one, they can be quite noisy when they're in use. This can be a problem if you're trying to enjoy a peaceful day on the water. Additionally, fins can be less effective in rough sea conditions, as the waves can cause them to lose their grip on the water.
As equipment and installation costs are comparable, purchase decisions usually need to be made on the performance characteristics of the systems, which vary due to their operational differences.
Sometimes, particularly in a refit scenario where the boatyard can be very confined in its decisions by other equipment and the basic layout of the yacht, the decision is made on different factors. Inconveniently located bulkheads and inner mouldings, for example, can mean it is difficult for fin stabilisers to be installed in the optimum location on the hull. Fin stabilisers are quite sensitive to their mounting location; they need to be located deep enough to ensure they cannot pop out of the water, while also as far outboard as possible on the hull so that they can generate sufficient righting leverage. This means hulls have certain ‘sweet spots’ where fin stabilisers will work well, but often these external positions do not correspond well with convenient or even possible positions to locate the fins’ extensive internal hardware.
Gyroscopic stabilizers, however, have much less sensitivity to mounting location. A Smartgyro stabilizer can be mounted in various positions aft of the centre of the boat, does not need to be located on the centreline and can even be fitted above or below the waterline. Often, gyros are most conveniently located in the engine space, with boatbuilders increasing considering a space for a gyro within the design of the engine compartment.
In a refit scenario, the necessary location of fin stabilisers can mean the extensive tearing out of internal accommodation, for cabling and motors, any later servicing of the internal units during the life of the boat can also mean technical crew are routinely accessing the owner or guest accommodation. Installation of a gyro stabilizer avoids this disruptive intrusion.
While some of the latest fin stabilisers can provide a limited stabilization force while the boat is at anchor, gyros are always superior to fins at slow speeds and at anchor. This is because fins require constant movement of water over their surface to work, remembering the aircraft wing analogy again - a wing must be moving to generate lift.
Which explains the single main advantage that fins do have over gyros. As speeds rise, the force fins produce rises exponentially, so fins can generate very large amounts of lift over 15 knots. This can also generate constant righting from one side, such as required to keep a flybridge cruiser level when underway in a strong sidewind, where gyros can only counteract changes in a vessels movement, not a continuous strong force in one direction.
Fins are located outside of the boat, and like anything that requires holes in the hull and in-water appendages, they need care in use and regular maintenance such as for antifouling, which necessitates dry docking of the vessel. Fins are also susceptible to entanglement or impact with flotsam and grounding damage, can impact docks and other vessels when berthing, and are best avoided for high latitude cruisers that could encounter floating ice. Fins that provide limited righting force at anchor also do so by making fairly sudden, rapid movements, meaning that swimmers cannot safely be in the water around them, and the very time swimmers enter the water is when the vessel is at anchor. None of these problems exist with gyro stabilisers as the system is entirely contained within the hull.
Fins provide drag too, even when entirely switched off in flat calm conditions impacting on both the vessel’s top speed and fuel economy.
THE SMARTGYRO BENEFITS
One of the significant advantages of the Smartgyro system is its ability to provide excellent stabilization both when at anchor and while underway, in total safety. The system can significantly reduce boat roll providing passengers and crew with a more comfortable and stable onboard experience.
Another advantage of the Smartgyro system is its ease of use. The system requires minimal maintenance and can be operated with a simple control panel or via the MFD, making it easy for owners and captains to adjust the unit to suit their needs.
Smartgyro’s modular design, which allows the units to be uniquely broken down into four parts, not only simplifies the initial installation but also allows most maintenance to be completed in situ. This specific design results in reduction of both cost and downtime, which means even more time to experience the joy of being out on the water.
In the end, choosing between different systems comes down to personal preference and individual circumstances. Both types of stabilizers are effective at reducing boat roll but have their own pros and cons. Regardless of the type of stabilizer you choose, be sure to do your research and consult with a professional to ensure that you're getting the right product for your needs.