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2001 Horizon 76 - Sea Trial

Discussion in 'Horizon Yacht' started by TahoeJohn, Oct 8, 2020.

  1. Capt Ralph

    Capt Ralph Senior Member

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    A red neck way to make sure all the blades are in the same position when the prop is spun by hand.
    The Idea is hold a pencil or rule or stick in place on the strut and then rudder and make sure each blade is the same distance away from the strut and rudder as the prop is hand rotated.
    From the rudder at different heights, rake can be compared between both props.
    My thought here is damaged blades can scoop more water and apply more torque to the hull causing a list. Not all damaged wheels vibrate.
    It's a reach of mind (que Twilight Zone music), but possible.
    Now that we feel the hull may have taken a hit, prop damage may not be that far out of mind.
    Last edited: Oct 13, 2020
  2. Capt Ralph

    Capt Ralph Senior Member

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    Re your picture; Something has changed for that list to appear and not correct it self.
    What was involved in turning around? Big round 180? Tight 180? Slow down, stop & spin?

    I wish we could talk to your surveyor (not supplied by seller or broker).
    At least, log your surveyor on to this thread.
    Remember, he works for you, not the kids hired by the owner to 'sposed fix something.
    Last edited: Oct 13, 2020
  3. Capt Ralph

    Capt Ralph Senior Member

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    Hate to say this so late, Could be air in the lines.
    Air compresses and expands and changes volume with heat. The worst thing to have in a pressure line.
    The wrong oil can cause foaming also.
    Air should clear from the gyro fine by itself. Air at the cylinder and in some lines may not self clear.
    I like the kids at Cable. I've been going thru them for many years. But even them (or I???) can mess up, and not bleed the system or install the wrong oil or look the wrong way.
    Frak, I've seen better yards have lines reversed and delivered the boat.
    So anything is possible. Maybe have to go over all this work to make sure all minds were/are clear.
    Last edited: Oct 13, 2020
  4. TahoeJohn

    TahoeJohn Member

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    I would upload the video if I could. The boat was always going in a straight line. Run #4: 2200 RPM, about 21.5 knots. The *only* thing that then changed was that the throttles were moved to WOT. Then the list happens.
  5. mapism

    mapism Senior Member

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    I wouldn't recommend anything, actually. Neither a full replacement nor any upgrade to the existing system.
    Not unless you are interested also in zero speed stabilization, which as I previously mentioned implies a full replacement of the system, in practice.

    Those Naiads are obviously old tech, but they are as capable to straighten a boat as anything more modern, regardless of whether driven by a gyro or by electronic sensors.
    New systems are different in many ways from an electronic viewpoint, and are interfaced to consider just about every boat status (like speed, rudders, gear).
    Besides, they are also capable of self-learning/adapting to the sea conditions and to the boat reactions.
    But the basic hydraulic operation isn't that different (if we leave aside the more recent and arguably more advanced 100% electrical fins), and if there is one thing that newer system do NOT bring to the table, that's a higher power/righting moment.
    That strictly depends on the fins size and their rotation angle, plus the boat speed, and there's no way that a more sophisticated controller can improve what your fins can already do while driven by the HMG controller.

    And what is funny (sort of) is that for any given fin size and rotation, a higher speed makes the stabilization MORE effective, not less!
    That's very basic physics, and also intuitive.
    This is the reason why it can't be a matter of fins not being able to cope with the higher speed - if anything, only the opposite could make sense.
    I mean, I owned for almost two decades a boat stabilized with that very same equipment, and if the stabs ever struggled a bit to do their job, it was at VERY low speed, up to 4 knots or so.
  6. mapism

    mapism Senior Member

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    That's precisely what I meant what I envisaged the possibility of a leak in the fin actuator (post #63).

    PS: talking of the actuators, a question for the OP, what model is installed on the boat?
    A consistency between the actuators/cylinders and the fin size is ESSENTIAL to the system.
    According to Naiad Application Guidelines, the 12 sqft fins could be mated to a range of actuators, from the smaller "300" series all the way up to the "520", depending on the vessel tonnage and length.
    But since the boat is within the tonnage and length limits also of the "250" actuator (which are only rated for fins up to 9 sqft), I am wondering if someone thought to save some bucks on the installation by mating the smaller actuators to the larger fins.
    Last edited: Oct 14, 2020
  7. mapism

    mapism Senior Member

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    Just one last thought, totally independent of all the technicalities discussed so far.
    In principle, a well designed planing hull should become more stable (i.e. more resisting to both roll and static listing) at higher speeds.
    And this is true regardless of any correction system - be them trim tabs of fin stabilizers.

    Was the boat behaviour tested also with no trim tabs, fins off, and rudders centered?
    If also in these "fully neutral" conditions she remains straight up to 21 kts or whatever, and starts listing right above that speed, I'm afraid it's the whole hull design that should be questioned, first and foremost.
    The fact that fin stabs could and should still be able to correct that (which remains true) would be just a patch to a bad hull.
  8. TahoeJohn

    TahoeJohn Member

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    Just received the EPE (Engine Performance Evaluation) reports from Pantropic. Here's one of the pages from the "Sea Trial Steady State Recorder":

    Screenshot 2020-10-14 092542.png


    It looks like at WOT, the port engine is working harder than starboard, which the Pantropic guy said isn't unusual. Fuel consumption is significantly higher on port at top speed.

    I don't know if this has anything to do with this heeling issue or not, but am certainly interested in opinions.
  9. Capt J

    Capt J Senior Member

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    It looks more like your fuel filters are dirty and that may be causing the port engine to simply make more power. Should see 100% load at WOT (and slightly higher rpm) on Starboard but only seeing 98%. Boost is the same so it's not a turbo issue. It's been a long time I've run 3412's so I forget what the fuel pressure should be, but over 65 PSI fuel pressure seems to ring a bell and usually you see the fuel pressure in the mid to high 70's PSI I want to say.

    Honestly I think the boat just has a semi-displacement hull design and once pushed that speed, simply wants to heel over and run on one side of the keel or the other.......the other issue (not really an issue but cause) with these Asian builds is they usually have fuel tanks on the outbound sides of the engines and a crossover pipe, joining the 2 tanks together, most people leave the valve open..... so if you have a little list, fuel from the higher tank, runs to the lower side, putting more weight on that side and causing more of a list.........frankly, I think it's just what the boat is and there's no issue with anything at all. It's a skylounge with a lot of weight and windage up high. I also would just leave the stabilizers and system that's on the boat on the boat without dumping $35k into it. If you're going to do that spend the real $$$ and get modern zero speed stabilizers or don't bother.
  10. TahoeJohn

    TahoeJohn Member

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    Thank you, Captain. I'm checking with Pantropic on their guidelines for fuel pressure, and if we proceed with this boat (which it looks like we will), I'll put new fuel filters on the list, just to rule that out.

    This boat does have the two side tanks joined with the fuel valve. Convenient when fueling, I guess, but then close it when operating to eliminate this cause of listing.

    We're going to have the boat hauled once more (to replace a leaking cylinder on the stbd trim tab) and I'll verify at that time that the stabilizer fins aren't somehow loose on their shafts.
  11. Capt Ralph

    Capt Ralph Senior Member

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    F M
    At least it's a start.
    Stb or port (see #8 above).
    Your surveyor reading this yet?
  12. Pascal

    Pascal Senior Member

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    What is the maintenance history? Every oil change, I replace the fuel filters and they always look pretty clean. I ve always seen fuel pressure in the 50s on both 3412Es and C32s. I doubt that s an issue.

    If a fuel imbalance was the problem it would manifest itself at lower speed not suddenly from 2100 to 2300 rpm

    if they’re going to haul out, I would also check that the port fin shaft is at the same angle as the stbd shaft. If after the work the new actuator was a few degree off, it could cause the boat to heel

    Btw, still wondering why they had to do all that work on the port fin. It does sound like a hit to me.

    In any case there is still the issue of a 76 footer barely breaking 21/22kts on a pair of 3412Es....
  13. Capt J

    Capt J Senior Member

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    You're failing to realize how big and heavy this 76' with 6' of draft is.

    https://www.yachtworld.com/boats/2001/horizon-76-sky-lounge-3688151/
  14. Pascal

    Pascal Senior Member

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    Maybe. I used to run a 70’ Johnson skylounge with 6 1/4 ‘ draft which hit 29.5 on the same engines with 5200 hours. The extra LOA also adds lift... I don’t know. Just seems very slow.
  15. Capt J

    Capt J Senior Member

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    The Johnson you ran was the exception. 99% of the other Asian builds don't run nearly as fast as your Johnson did......most are slow, Taiwanese tubs.......
  16. d_meister

    d_meister Senior Member

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    +1
    Hard to get accurate unless both fins are below the keel, but you could tape plumb bobs from the front fin center line and the rear fin center line, then measure on the ground.
    The need to rebuild the actuator bases is odd, though. It could be from excessive actuation. I ran an 80' motor yacht that had chronic NAIAD (on-center-off type) stabilizer actuator cylinder issues when I took over. The actuators moved quite violently, and had a tendency to force seal material out of the cylinder cap around the actuator rod. Had it looked at three times in my first year, and got nowhere. In the second year, I finally had enough time to look at it myself. Just looking at the basics, I saw that the Gyro oil pressure regulator had an incredible number of shims in it. All the pressures were right by the gauges, so I guessed and bought a new Gyro pressure gauge. Sure enough, gyro pressure was sky high, and the performance issues were all solved by getting the gyro pressure to where it belonged (900 psi?). Second year was quite peaceful. Relatively.
    Anyway, Capt Ralph is right about proper diagnosis and pressure gauges.
  17. Dickie Barker

    Dickie Barker New Member

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    I find this discussion very helpful and educational. I am in the process of purchasing one of these boats. New to the forum but look forward to more .