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Waveless Stab stabilizers

Discussion in 'Stabs, Tabs & Gyros' started by JadePanama, Feb 12, 2021.

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  1. olderboater

    olderboater Senior Member

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    I don't appreciate the implication that by praising Sleipner one has a vested interest with them. It seems anytime one has an opinion you don't agree with you take shots at them. Please don't make accusations like that when one has an opinion different from yours. It's possible to respect another's opinion, even if you disagree with it.

    I do praise Sleipner as does Capt J. I owned a Sunseeker Manhattan 65 with them and covered over 9000 nm in that boat. How much have you run a boat with Sleipner Vector Fins? Before buying I also tested the same boat with gyros. I've run similar sized and styled boats with Naiad and with ABT. I'm sure Capt J thought I was exaggerating until he ran a Sunseeker Manhattan 66 with them. I can't speak to all boats or all situations. I can simply say on the Manhattan 65 they performed exceptionally well and better than other systems on that boat. They did the job well at both speed and at anchor. There is no vested interest there. I thought before running them that the information was likely all hype. I was very pleasantly surprised.

    I cannot speak to CMC. I have a lot of experience with Naiad and very good luck and know a lot of ABT fans, although some less certain since their acquisition. Our most recently purchased boat has Humphree Interceptors and Fins and I've been amazed at that combination. I saw the information but again can't tell how much is real. For instance, the talk about the fins rotating 360 degrees at anchor. Well, I don't know how much that does, but I know the system worked well at anchor. I will say they have some very impressive sea trials of Cranchi and Sunseeker on their web site. Now all they show also have their Interceptors so I don't know how one would know much of the Fins by themselves.

    Like you, I am not a fan of gyros, especially on the boats under discussion. I do think one thing they have done. They've pushed others into really working on improvements to zero speed systems. As a result, I think you're seeing great improvements in fin systems which were already performing well at speed but now are doing so at anchor. I hope so, because I don't like the idea of having both fins and gyros on a boat and my favorite builder is doing that widely now. I think on fins we're going to see a typical technology situation where the one with the most recent introduction is slightly ahead until the next one jumps them.
  2. mapism

    mapism Senior Member

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    Yet again shooting the messenger rather than discussing actual content, OB?
    I never, ever disagreed that Sleipner fins works very well.
    I just think that they do because they are good stabs, not because the fins are curved.
    In fact, their fin stabilizers were very good also before they introduced curved fins.

    The reason why your experience is irrelevant is NOT that my experience matters more than yours (or the other way round), but it's that it's very far from being scientifical.
    The only scientific way to compare straight vs. curved fins would be in fully AOTBE conditions, and to my knowledge not even Sleipner ever did that - let alone any independent institute.
    OTOH, what I said ref. very large fins used on megayachts being all straight is a simple observation of the reality, not an opinion.

    Even having never tried any Humphree stabilized boat, I am sure you are correct in saying that a system with STRAIGHT fins worked very well at anchor. :D
    Do you know why? Because they all do, it's that simple.
    If properly sized and tuned, obviously.

    The 180 (not 360) deg rotation during zero speed operation has only to see with avoiding the "swim forward" effect introduced by fins, whenever neither wind nor current is keeping the boat away from the anchor.
    Effectiveness in roll stabilization doesn't depend on that - and neither on interceptors, which at zero speed are as useful as a chocolate teapot.
    BTW, only electrical systems allow the full fin rotation, which is obviously impossible with hydraulic actuators.
    Last edited: Jun 22, 2021
  3. mapism

    mapism Senior Member

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    I meant to comment on previous post but I forgot.
    Not sure of who you have in mind, Westport possibly?
    Anyway, there's actually something to be said about the choice of fitting both gyro(s) and fins, because you can use either system where they work better - namely, fins for cruising and gyro for zero speed.
    And it's not like you are completely doubling the cost either, because the fins can be smaller and the whole system much simpler, compared to zero speed fins.
    Lastly, eliminating the risk of flipping fins that could easily kill someone swimming around them while anchored can be a very important factor for someone - particularly when operating the vessel also commercially.
  4. Capt J

    Capt J Senior Member

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    My non scientific experience. The curved fins worked amazing on the 66' Manhattan. Unlike any other type of stabilization I've used, and I've used most all of the different brands. I believe the curved fins don't slow the boat down like large traditional zero speed fins. But I've also seen where they help with pitch at anchor.....now possibly it may be for other reasons such as pushing the boat forward a hair so the bow isn't bobbing on the anchor chain.....idk.....

    There's one yacht I run a lot that performs worse at cruise 1/2 of the time with the gyro on, that 1/2 of the time I run it with the gyro locked.....the gyro is also undersized..........but anytime the waves are from the stern area.....think stern light degrees of the stern......it makes the boat flop on it's side when it rocks and it stays there at a list for 1-2 minutes at speed.

    Gyro's generally shine at hull speed and below. They are also good in areas with a lot of debris and logs since you don't have anything protruding from the hull.

    If someone is swimming, turn the stabilizers off!!!!! No different than having the engines off if someone is in the water.
  5. mapism

    mapism Senior Member

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    I tend to agree that turning fins off when anyone is swimming would be safer, but in my experience most owners / captains are happy with just placing warning labels along the hull sides and briefing everyone onboard about the hazard.
    In fact, I took some videos myself of zero speed fins working while snorkeling arount them - of course at reasonably safe distance.
    That said, sh!t can always happen, particularly with children who might be not so careful about any briefing...
    That's why I mentioned this as an advantage of gyros, at the end of my previous post.
  6. John Linn

    John Linn New Member

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    Reviving this thread in hopes of getting an answer to the simple question… does anyone have first hand experience with CMC Waveless fins operating at anchor and at displacement speed (8-9 kn)? I am considering either a SeaKeeper 6 or the Waveless STAB 20 for our new NPY45 being built now.