To A New Paradigm With FPB

FPB 64 Get Home Trials

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And now for something different. We are pleased to report that FPB-1, Avatar, has just finished her first day of testing with the swim platform extension and get-home engine. The lovely clean release above is at eight knots with the little Yanmar pushing her along.

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The first day’s results are in shallow water, with moderate breeze, so we don’t have any real detail to report. What we do know is the following:

  • Maneuvering at speed seems unaffected by the addition of the second prop skeg.
  • The increased drag of the second prop and full skeg appears offset by the swim step extension’s drag reduction.
  • With the Gori feathering prop in normal pitch mode, wide open throttle reaches 3400 RPM– so there is sufficient margin for a fully-loaded boat in head seas (engine prop curve needs only 3200 RPM).
  • It looks like 8.5 knots should be possible at around 2800 revs when the prop ┬áis in overdrive mode.
  • Maneuverability appears good on the get-home engine at slow speed. Clockwise turns are favored with the offset, of course, but counterclockwise also works.
  • Wide open throttle on the main engine yields in excess of eleven knots.

We shall update again when more data is available.

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Posted by Steve Dashew  (February 2, 2012)




22 Responses to “FPB 64 Get Home Trials”

  1. Jeremy Says:
    Would it be possible to run both the get home and main engine at the same time? Would this give a boost to the possible top speed?

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    Steve Dashew Reply:

    Jeremy: Possible to run both, but the main has more power than is needed 99% of the time, so probably not very efficient.

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    Kees Reply:

    Why not mount two “small” Yanmars then. Give both a Gori and run only one engine at 90% which is the most efficient for a Diesel (it will probably last longer as well!) For manouvering in harbour, when top speed is needed or when conditions are really bad you can fire up the 2nd engine. – A Yanmar Fan.

    [Reply]

    Steve Dashew Reply:

    No where near as efficient due to prop size/type and RPM.

  2. Pat Says:
    Hi Steve Love that folding prop – very sleek when folded. Curious what we are seeing above left of the new prop – two new hull penetrations? I thought that was against your philosophy? Cheers Pat

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    Steve Dashew Reply:

    The only thing added is an above the waterline exhaust for the get home diesel.

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    Raj A Reply:

    I think they are bosses for the hull zinc –raj

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  3. SARAH-SARAH Says:
    Steve- Was the shaft break used when running the get-home engine and, if so, was it able to hold the main shaft from rotating at speed? Bill.

    [Reply]

    Steve Dashew Reply:

    Hi Bill: Tried and not able. Circa are trying some mods, but it was never intended to hold the prop with the boat moving, and I doubt it will be able to develop the friction required. ZF have told us in the past that if we overfill the main tranny with oil, this will take care of the lubrication as the prop spins without the engine running.

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  4. Raj A Says:
    Couple of observations: 1. I have seen some pre-oilers that pump oil into engine before it is turned on. Could the same concept be adapted to create a bypass oil ciculation system for the transmission using the oil change pump? 2. Is the swimstep longer on avatar longer than the series 2? –raj

    [Reply]

    Steve Dashew Reply:

    Swim step is the same.

    [Reply]


  5. Daryl Lippincott Says:
    If one assumes that fuel economy is a high priority one would rarely use more power than is available from the continuous rating of the 4 cyl. JD engines in your FPB 83. Would you discuss the -+ of using one of those as the main engine in the 64 and firing up the wing engine for times like crossing a bar / inlet or other times when more power is desireable? Love the Wicked. Wish the lottery had better odds…. Daryl

    [Reply]

    Steve Dashew Reply:

    Hi Daryl: No time to get into this topic. But, if you want to go down t hat road, then fit twins – which on the 64 costs efficiency and the third sleeping cabin.

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  6. Daryl Lippincott Says:
    Hi again Steve, Would you run the ZF trans at higher than normal oil levels all the time or only when free wheeling for long periods?

    [Reply]

    Steve Dashew Reply:

    Only when free wheeling.

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  7. Scott Evangelista Says:
    Steve. I think Pat was looking at the attachment points for the zincs. Can’t wait to see the data. The additions look great

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  8. Chris Says:
    Wow, 8.5 knots is plenty of speed in some situations. Is it foreseeable to use the wing only heading down the Intercoastal Waterway, for instance?

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    Steve Dashew Reply:

    It is certainly possible to cruise with the wing engine. But the main will be 10/20% more efficient due to prop characteristics.

    [Reply]


  9. Doug Says:
    If you are going to have a smaller get home engine, why not have 2 mains?

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    Steve Dashew Reply:

    The single engine offer slightly better efficiency, the prop has better protection in ice, and it allows the third stateroom outboard of the engine room.

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  10. Neville Says:
    Why not an electric motor driven by the generator (and house batteries) for the wing engine? Simpler more compact solution. You would need to have an appropriate controller but that’s easy to get nowadays. You then also have the option of another backup for your alternator(s)at other times.

    [Reply]

    Steve Dashew Reply:

    Interesting question regarding electric get home. Easiest answer is we don’t know of a system we would trust to take us across an ocean.

    [Reply]



Comments or Questions?