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Gyro Stabilizers

Discussion in 'Stabs, Tabs & Gyros' started by johnnry, Oct 2, 2019.

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  1. johnnry

    johnnry New Member

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    I see even some of the med. boats have added the gyro stabilizer option so most likely the stern is not deep enough for real rough (meaning the stern deadrise is flatish) or wavy anchorages but my god I cant imagine the fuel consumption if these boats were any deeper..:(:oops:...would like to hear what you guys think about those gyros?
  2. Fiammetta42

    Fiammetta42 Member

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    They ( gyros ) are only really effective at anchor or displacement speeds - stop roll etc .keeps your plates on the table if another boats wake hits .
    At planing speeds the boats own dynamic stability takes over and the benefit at slow speeds is gradually lost as you go faster to be of marginal if any benefit at all in a big sea .
    So folks are disappointed at fast planing speeds with gyros .

    Fitting a gyro to a low dead rise boat isn’t going to alter its head seas performance.It will still slam .

    As far as fuel consumption goes , wetted area = drag .
    But in correctly configured high dead rise like Itama they have majored on lift inducing tactics in the hull design like enlarged full length lifting strips .
    As you go faster the boat lifts up thus reducing the wetted area .
    Additionally ( not wanting to drift ) the under water exhausts outlets are configured to reduce / air rate the area behind thus reducing further drag .
    The rudder arrangements have lifting rudders thus reducing blade drag .
    The engines are mid mounted ( destroying any countenance of a vast mid cabin ) .This helps the angle of attack .Ie they run flat with minimal flap .They also have lower than average shaft angles thus minimising thrust lost .
    They also have in a money no object attitude over large engines thus max power .
    It’s this power that creates the speed and lift .
    Because the engines are over powered compared to competitors ( similar L ) you run them lower down the rev range or turning it around along way from the near exponential fuel gobbling right hand side .

    So it’s the sum of a lot , not just a few details .
    A deep V hull needs the rest of the package .
    But you are right it should not be taken in isolation.

    It’s part or should be of a basket of measures.

    Dead rise a good place to start as it’s quantifiable .
    Last edited: Oct 2, 2019
  3. captholli

    captholli Senior Member

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    Excellent post with good explanations and reasoning.
  4. Capt J

    Capt J Senior Member

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    Except the fact that gyro's are still effective at planning speeds. That I can assure you. They are only about 30-50% effective at planning speeds, but it is still a very noticeable improvement. Hull speed (or slower) and anchored is where they really really shine. I've run lots of seakeeper boats and they do improve at cruise speed. I've also been playing with a yacht with the side power curved stabilizer fins, those are as good if not better at anchor as the seakeeper AND they help with fore and aft movement at anchor a bit too. I'm really impressed with them, aside from the minor issues we've been having with the system, but it's a new boat and some new boat issues.
  5. captholli

    captholli Senior Member

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    Veem is the only manufacturer at the present time producing a high speed (RPM) units for non displacement vessels and the only manufacturer to publish data to back the findings of roll reductions @ "on plane" speeds. Seakeeper is playing catch up at this point but they are introducing new products to compete with Veem. Lets hope that Seakeeper has corrected the internal gimbal bearing problems with the new line of high speed gyro's. Interesting that you've had experience with a fin stabilization system that could alleviate "pitch" or fore and aft movement as you called it. Outside of an active canard ride system , any reduction in pitch is unheard of from fin stabilization. What system was this that reduced pitch while anchored or underway?
    Last edited: Oct 2, 2019
  6. johnnry

    johnnry New Member

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    Thanks ,Capt J,thanks for the comments on gyros at plane..I'm sure their effectiveness at speed is entirely specific to each hull design..as far as itama and magnums,well I think we where talking about sporty lux. Suv's and your comparing to corvettes lol
  7. Capt J

    Capt J Senior Member

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    Fiametta42 is saying that gyro stabilizers benefit is marginal if any benefit when underway at speed. With the standard seakeepers you do still see a benefit when underway at cruise speed. Their reduction at roll is less impressive than when at hull speed, drifting, or anchor. BUT, it is still there and still noticeable. I would say it reduces roll at cruise speed in the dozen or more different Flybridge motoryachts or SF that I've run them in at cruise, somewhere in the neighborhood of 30-50%, generally closer to 30%, but you still see a noticeable difference over not having them at all. I've run dozens of different seakeeper boats. Today I ran a newish 55' Azimut FB that had a seakeeper, yesterday and the day before a new 44' Tiara FB with a seakeeper, and have never run either model of those prior. Every seakeeper boat I've ever run is a planning hull, so not even sure about the comment about non-displacement boat is about. Almost every seakeeper test is on a non-displacement planning hulled yacht on their website. Every Princess comes with beefed up stringers in the place designated to put the seakeeper, regardless of whether or not the owner ordered one. There are times in an aft or following sea on some yachts where I have to lock the seakeeper because it makes the yacht too stiff and when rolls to one side will keep it there for 20-30 seconds. Yes, Seakeeper on publishes data at rest or drifting on their website, but I can assure you that they're a noticeable help when running at cruise. Granted, fins are even more effective at cruise from what I've seen, maybe even twice as much...……. I run 100-150 different yachts a year from all different types to all different manufacturers. I've run 7 different yachts on multiple occasions even on the same day.

    The faster you push any hull, the more stable it will be generally. IN the case of Magnums and Otams and such, when it gets rough enough that you have to start slowing down from your 35-45 knot cruising speed to somewhere in the 20-35 knot range, a seakeeper or other gyro will start helping retain the stability more and more. But you're talking about a very very small segment of the yacht market. Heck, has Magnum produced more than one yacht in the last 5-6 years?
    Last edited: Oct 2, 2019
  8. olderboater

    olderboater Senior Member

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    As to Seakeepers at speed. Do they do anything? Yes. Perhaps a 30% reduction at 25 knots. Does that fit the definition of effective? Depends on who you are.

    However, when I see what Sleipner/Side Power Vector Fins will do on the same boat, then I could never be satisfied with Seakeeper on a planning boat as they perform today. 30% isn't enough for me.

    Many larger planning boats are installing Seakeeper and Naiad Fins.

    I'm not knowledgeable on Veem and perhaps need to learn more about them. However, at their current level and since I'm only interested in running on plane, Seakeeper by itself is not a solution I'd consider.
  9. Capt J

    Capt J Senior Member

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    Depends what you're doing. The beauty of the Seakeeper is you don't have anything additional protruding from the hull. So, in the case of a boat that travels in areas with lots of Debris......PNW or the Loop, etc. That might be advantageous to some.
  10. Capt J

    Capt J Senior Member

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    The side power curved Vector stabilizer fins. At anchor they sweep in parallel with the boat hull and then kick straight out parallel with the boat (similar to someone paddling, they don't turn side to side like traditional fins (or a rudder)...…. Olderboater has personal experience with these fins and owned a boat with them as well. Several manufacturers are putting them on as standard equipment. I've found we lose .4-.5 knots at cruise with them on versus locked. But the first trip I did with them was Miami through the Exumas as far as Staniel Cay, 7 nights, 4 of them anchored at 4 different locations. Also did a 2 day trip and anchored overnight. I've been very impressed with them and there's no noise when at anchor. I've run a lot of different sea keeper boats (as well as trac, wesmar, etc.) and these are even better than sea keeper at anchor or at least equivalent, at speed they do a great job.

    See the link below...
    https://side-power.com/kategori/1978/vector-finstm/
  11. 101TUG

    101TUG Senior Member

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