Just a couple of years ago, boat stabilization, that is the possibility to equip your boat with an anti-rolling system, was still the preserve of big recreational ships. First of all, because of the size of the systems involved in this task: fins emerging from the hull; secondly, because of costs. Moreover, this type of stabilizers worked only when the boat moved. More recently, the so-called “zero speed” stabilizers have come: they keep the boat steady even when it is docked, which is the most delicate situation for guests on board.
The art of gyroscopic stabilizers
A considerable step forward has been represented by the advent of gyroscopic stabilizers which don’t resist motion through submerged fins but use the same principle than gyroscope, that is a tool which, like a top, uses the rocking motion to keep balance around the rotation axis. In practical terms, what we install is a rotating mass that, sized as a function of the boat to be stabilised, moves and reduces boat roll. Which are the advantages of gyro stabilizers when compared with traditional systems? First of all, a least resistance to motion since they do not feature any parties external to the hull; through-holes are totally absent or very small ( in the models that need water to cool); easier installation ( the box containing the gyroscope can be installed anywhere, even on the flybridge; it work always, provided that structural parts can support a considerable ton-force, or better, the kilo newton meter force opposing the roll); more compact size, which makes these systems suitable even for 10-meter boats. However, the gyroscope works only at a specific spool-up speed, which means that it takes about 30 minutes to be operative. During this phase, consumption is higher than the normal use stage. The system takes twice as much time to spool down.
The third way: Magnus effect
Another interesting category includes stabilizers using the so-called Magnus effect: a cylinder immersed in the water moves from left to right if it rotates clockwise and creates an upward force (like a wing); on the contrary, if it rotates counterclockwise, it creates a downward force (of course, phenomena are reversed if the water flows the other way). Higher the speed, greater the effect. The essential thing is that water moves, which means that, if the boat is at the anchor, the systems works the same, provided that the cylinder moves. Less expensive and lighter than gyroscopes, these stabilizers have always all their parts immersed. However, these sections are infinitely smaller than fins. A single Magnus Rotor features the same lifting force than a 1.4 m² zero-speed fin or a 1.2 m² fin running at cruising speed but with a surface of just 0.14 square meters. The choice of the right stabilizer should consider the displacement and not the length of your boat. As for the torque, this should be selected according to the size: about 5 kNm for a 8-ton boat; about 6.5 kNm for a 10-ton boat and 120 kNm when boat displacement ranges between 50 and 130 tons.
Find your way through the market
Probabilmente il nome più noto tra i produttori di stabilizzatori giroscopici. Offrono due linee, la Recreational e la Heavy Duty che si differenziano per tipologia di utilizzo, ovviamente più intensa nel secondo caso, e per la durata della garanzia che per la linea HD è di quattro anni invece che due.
It’s probably the most famous among gyro stabilizers manufacturers. The brand offers two lines, named “Recreational” and “Heavy Duty” which differ for the type of use, which is more intensive in the second case, and for the duration of warranty which is 4 years, instead of 2, in the HD line.
Giri/Rpm: 9000; peso/mass: 188 kg;
prezzo: € 19.000
Quick – MC2X 5k
Thanks to a fly-wheel revolving around a horizontal axis, bearings suffer less friction at lower temperature: they don’t need any water-cooling or vacuum-sealed system and they guarantee easier installation and maintenance.
Giri/Rpm: 5000; peso/mass: 300 kg;
Price: 17.300 €
Tohmei Anti Rolling Gyro (ARG) 50t
The Japanese manufacturer, leader in the segment of megayachts equipment, introduces the first models for small-sized boats and proposes the ARG 50T/65T, for boats up to 10 tons. A constant current battery is offered as part of standard equipment.
Rpm: 4200; mass: 236 kg;
Price: Y 1.550.000 (11.600 €)
Zipwake, the world’s first inexpensive dynamic trim control system, incorporates a state of the art series of durable, fast-acting interceptors, eliminating the well-known trim problems of planning and semi-planning boats between 20-60 feet.
Price: from .2000 €
This stabilizer doesn’t use the gyroscopic effect but the Magnus effect (see the text above). In addition to being immediately operative, it offers three different modes: Zero Speed, Cruising (between and knots) and Rake, when running at over 14 knots.