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Yacht Stabilizers

Discussion in 'Stabs, Tabs & Gyros' started by John B, Jun 2, 2004.

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  1. John B

    John B Senior Member

    Joined:
    Jan 28, 2004
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    New York
    I am curious about stabilizers and how they work.

    Are these all computer controlled these days?
    What size boats do they start appearing in?
    How basically do they work?
    Are there many different designs for these?
    Do they all work in forward/aft and roll side to side?
    How effective are they in reality?

    Conceptually "I think" I understand what these do, but it's an area where I would like to have a better grasp of what these are, how they work and different types.

    Hope this isn't too broad of a question!

    Thanks in advance,
    John
  2. mik-48

    mik-48 New Member

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    Slovenia
    all stabilizers works on a principle of gyroscope.More specifically, the gyroscope tends to resist any power applied to it, but when it is applied it reacts so that its axes moves perpendicularly to the power applied.
    In case of boats the applied power is achieved thru movement of the boat ( rolling ).

    The whole staff, consists of a hydraulic plant, gyroscope and of coarse the fins.
    Rotation of the gyro is achieved thru the hydraulic turbine to which it is connected at one side,while the other side serve to control the valves in the hydraulic system in order to properly swing the fins. Basically as the boat rolls the gyro axes moves fore and aft and so opens and closes the appropriate valves.
    The only thing which can be controlled by the user, is synchronization of the movement of fins with rolling of the boat.

    All stabilizers are effective while rolling, they have no effect on pitching of the boat.

    Tough there are no specific limitations on the size of the boat where they should be installed, it make sense to install them on boats 60 feet and over
    ( my opinion only)
  3. JHA

    JHA Senior Member

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    More and more stab. systems have computer controllers which often eliminate the need for any user input. Also - I believe that a four-fin configuration (as found in many lazzaras) will help control pitch to an extent.
  4. John B

    John B Senior Member

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    JHA,

    That was my understanding that some of these can control pitch as well, but I'm really not sure.

    If it is not computer controlled, what is the 'user input'?

    John
  5. John B

    John B Senior Member

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    Just saw an article in the newest issue (July) of Power & Motoryacht on new designs in stabilizers. Very interesting.

    There are several new designs, including one from Ferretti and Mitsubishi that uses a large gyroscope and no fins. Also some that work while the vessel is at anchor and designs that handle pitch as well as roll.

    According to the aricle, analog based systems from 15 years ago could dampen about 40% of roll in three to four foot beam seas. Digital sysems are much more responsive and can now eliminate 90%-98% of roll in same conditions.

    Pretty good article.
  6. OceanFlyer

    OceanFlyer Guest

    New Stabilizer Types

    New stabilizer systems include roll, pitch and yaw (steerage assist in following seas) Control. The most advanced system uses digital control and dual T-Foils (from hydrofoil technology) mounted on the transom. It controls all motion underway and roll at anchor.

    Stabilizer systems are normally installed on power yachts 36' and up. All yachts benefit from stabilization. Once you have spent time on a stabilized yacht, nothing else will do.

    All rely on a roll/rate sensor connected to a hydraulic control system which directs underwater hydrofoils of some type to move in a direction to produce lift. This lift works to oppose the motion induced on the boat by the weather and sea.

    The trend now is to install systems which control all motion underway and roll at anchor.