FPB Motion in Gale Force Conditions

Discussion in 'Boat Design' started by Steve Dashew, Jan 5, 2009.

  1. Steve Dashew
    Joined: Jan 2009
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    Location: Arizona

    Steve Dashew New Member

    As there has been a lot of discussion about the sea keeping ability of the FPB design series and how they actually work offshore some video might be of interest. If you visit http://dashewoffshore.smugmug.com/gallery/6802329_jB96x#435385653_PzJDW you will find video of the FPB 83 in a force 8 gusting 9 gale in the Tasman Sea. There are other videos as well, but this has the "best" conditions. If the URL is too long just go to www.SetSail.com/fpb and click on the Video link and it will take you to all of the posted videos.
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  2. marshmat
    Joined: Apr 2005
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    Location: Ontario

    marshmat Senior Member

    Hi Steve,

    It's nice to see you joining us on here. Many of us have been following the FPB project for a while, and I for one am very glad to see the new 64 in production. It's always fun when someone goes against the current trends to come up with something new and better.

    I saw a few of the videos you posted after the shakedown cruise. It does seem like you are on to something good with this hull.

    How aggressively did you have the active fins going in the clip you mention above? I still have a bit of a hard time believing that a relatively narrow hull could ride so level in swells with the fins set low or off.

    Looking forward to seeing you on here as well as the regular SetSail updates :)
  3. pkoken
    Joined: Mar 2003
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    Location: Cruising Hawaii

    pkoken S/V Samadhi V

    Seeing the motion with the fins off would certainly be interesting! I am assuming that the tanks were full (of water) here and the booms are deployed?

    Pitching is minimal, and this something that the fins don't help with.

    I notice a bit of yawing, but the narration says that the gain is down on the autopilot? Do you pick up efficiency from backing off on the gain / deadband settings?

    Finally, since this is a following sea I would love to see the same video going the other way!
  4. Steve Dashew
    Joined: Jan 2009
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    Location: Arizona

    Steve Dashew New Member

    Hi Phil:

    We found that the boat tracks well enough that she needs minimal pilot input running, even in good sized seas. We typically leave the deadband set at four degrees and the gain at one. By contrast, waves on the beam we set deadband at 1 and gain at 4.

    Booms are out for windage (as we are running) and increased polar moments (to increase roll period). But nothing is in the water off them.

    We tyically have the equivelent of full fuel if there are big waves (filling water tanks as we burn diesel).The the video heading to Fiji from New Zealand, this is just a day out of the Bay of Islands, so our liquid payload was on the order of 3700 US gallons.

    Re uphill, look at the video from the Bahamas to Nova Scotia http://dashewoffshore.smugmug.com/gallery/6802329_jB96x#435202827_m5uCv-A-LB
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  5. Guest62110524

    Guest62110524 Previous Member

    love the lines
    Scott Carr and Lowie bos worked for me short time before they went alone
    But they did not build this one?

    Tasman can get bad, did same in winter of 01 heading to Brisbane so it was on the nose, similar forefoot to yours, still , how many seconds did you count dead silence until you landed in the trough,
    :)) and what speed did you make into it, ( cant run your footage)
    I have some belting extrusion and rail cap you may like to look at will email you
  6. sabahcat
    Joined: Dec 2008
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    Location: australia

    sabahcat Senior Member

    Nice videos Steve, thanks

  7. chabrenas
    Joined: Jan 2009
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    Location: France

    chabrenas Mike K-H

    Thanks for this. I've seen photos and sales pitches over the years, but the videos show me what's it's really about. The majority of superyacht owners should view them before their next purchase - assuming, of course, that they own their boats because they love the sea rather than because that's the easiest way to maintain the kind of isolation and security that they seek...
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