FPB 64-3 Sea Trial Runs Three and Four

Iron LAdy second trial 2012

We have the complete set of data now from Circa on Iron Lady’s second set of runs. The data looks as expected for her displacement running in deep water and calm conditions (numbers are on the ┬ánext page). She also appears to be a touch quieter, although without soft goods installed this is difficult to tell for sure.

FPB64 3 runs3 4

The table above represents the RPM range where the boat would normally be run. Keep in mind that these figures are going to be impacted by the boat being at full displacement (where cruising boats tend to operate) and by auxiliary loading for hydraulics and DC power generation. You would also knock off for rough water and wind drag (or add if the wind and waves are behind you). Anyway you slice these, they are efficient and in accord with the visual impression from the bow and stern wave photos.

Iron LAdy second trial 2019

Speaking of which, the picture above, and second wake shot in the previous post, were taken at wide open throttle, that’s 11.6 knots, or a speed length ratio of 1.45. You can force almost anything to this sort of SLR with enough oomph. In the case of the FPB 64 this represents 235 horsepower.

You are going to think us obsessed with bow and stern waves (which we freely confess) when we tell you this is an amazingly sexy transom release of stern wave pressure.

Posted by Steve Dashew  (February 8, 2011)

5 Responses to “FPB 64-3 Sea Trial Runs Three and Four”

  1. Roy Rhinehart Says:

    I have enjoyed following your adventures for years. Are you contemplating putting an extension on Wind Horse? Keep up the great work.

  2. Steve Dashew Says:

    Howdy Roy:
    Wind Horse has her “extension” already, but it was part of the original waterline, since she is already well beyond the 30m/65′ rule length. That said, she would benefit from even more LWL, but the gains would not be as dramatic as with the FPB64. Bottom line, more LWL is always better, rules and dock issues notwithstanding.

  3. Richard Says:

    Steve, I would LOVE this top picture (bow) for my desktop! Would it be possible to get a higher res version? Thank you.

  4. Robert Says:

    Off topic, but why the non-skid on the 64s and the diamond plate on the 83? Owner preference?



  5. Steve Dashew Says:

    Hi Robert:
    Aesthetics… The Treadmaster has a much more refined look, and is a little less slippery than tread plate as we have on Wind Horse.