We have all been there, caught unexpectedly in rough seas that hit the boat broadside causing uncomfortable rolling of the vessel from side to side. Stabilizers help dampen the roll for a more comfortable ride.
There are several different types of stabilizers; and boaters now have the added option of the new laminar flow stabilizer, described in this article. Here are some things to consider when selecting a stabilization system:
- Gyro Stabilizer – is a heavy spinning disc turning at high RPMs. When the boat rolls, the spin of the disc is in opposition to the roll. The gyro is governed by software that senses the motion of the hull. Gyros have no external appendage in the water so there is no drag or exposure to being damaged by debris in the water. For fast boats, say a 30-knot boat, the gyro has to be much bigger and space may be limited. With few exceptions, the gyro is wholly dependent on AC power off the generator.
- Active Fin Stabilizers – as water flows over the wing surface, the fins alter their angle based on the rate of roll to generate an opposing force. The power of the fin increases with speed exponentially generating lift and stability. They also help the vessel bank into turns. They are much lighter than gyros, and maintenance of bearings and cylinders can be done in place. The downside is the fact that fins are appendages that protrude downward and outward from the hull, and are prone to damage by debris in the water. They also create drag, reducing fuel efficiency. For installation, fins must be positioned roughly at mid-ships which may pose a challenge when retrofitting an older boat. Fins require ample structure and support.
- Paravane Stabilizers – a boom system on each side of the vessel that is lowered manually to a nearly horizontal position by the use of controlling gear. A delta-shaped metal “fish”, at the end of chain attached to the boom, drags through the water reducing roll. Paravanes give the look of an offshore commercial fish boat and have to be deployed carefully. On larger yachts, paravanes can become unwieldy, so are not normally used for short runs. The “fish” creates more drag than do active fin stabilizers and can reduce speed and cost fuel. While paravanes are relatively inexpensive, the controlling gear needs to be properly arranged to allow for safe handling.
- Laminar Flow Stabilizer – this is the new generation of stabilizers, with a cylindrical arm (rotor) that extends perpendicular on each side of the vessel when activated at the helm. The rotors or arms spin in opposite directions, providing lift and stabilization. This new stabilizing system is especially suited for low-speed displacement and semi-displacement vessels up to 90 feet. Roll damping is achieved as low as 3 knots and up to 12 knots of boat speed.
How the New Laminar Flow Stabilizer Works
The movement of the vessel through the water produces a laminar flow over the MagnusMaster rotor(s)/arms that in turn produce either an upward or downward force depending on the direction of rotation of the rotor. For example, as waves hit the port side of a vessel, the port side rotor will spin clockwise while the starboard side rotor will spin counterclockwise providing lift. This Magnus effect was discovered and documented by Heinrich Gustav Magnus, and has been perfected by Dynamic Marine Systems of Holland.
The arm/rotor is retractable when not needed, thus less vulnerable to damage. The swivel knee (elbow) that extends the rotor is secured by a series of shear bolts, which helps prevent damage to the hull in the case of a debris strike. The MagnusMaster Rotors do NOT need to be positioned in the mid-ships area of the vessel, so it’s easier to find a suitable location within the engine room. A control cabinet houses all the control electronics, including the motion sensors.
The MagnusMaster stabilizer system is activated by a touch screen at the helm by pressing ‘stabilize’ to deploy, or pressing ‘park’ to retract the rotor, which tucks parallel along the underside of the vessel’s hull. The rotor(s) also self-retract when the engines are put into neutral, or pass through neutral and into reverse. They will only deploy again when pressing ‘stabilize’.
The new generation laminar stabilization system is popular in Europe and has only recently been introduced in the U.S., with a dealer in Ft. Lauderdale, Florida. The manufacturer, Dynamic Marine Systems of Holland, also specializes in producing other stabilization options, including the unique Anti Rolling Gyro, and unique fin stabilizing systems for both low speed and high-speed vessels. For more information, go to www.dmsholland.com.
Illustrations and Photo: Dynamic Marine Systems