[Public-List] A30 Hull Prismatic Coefficient

[David A. Bardsley]

   Gordon,
   That is an awesome data point, thank-you very much.  It helps
   corroborate something I'm seeing in these spreadsheet calculators.
   One such tool is predicting 4.4kts at 1000rpm and 5kts at 1150pm.  This
   data point of 5kts at 1000rpm will help me calibrate this tool's s
   coefficients so I can make meaningful predictions throughout the entire
   power band.
   Right now it feels like I'm zeroing in on 1.65:1 as the optimal match
   for one specific motor's dyno data and my 13-8 sail prop.
   Dave
   Ginseng 574

   On Jun 28, 2021 22:45, Gordon Laco <mainstay at csolve.net> wrote:

   Here’s a bit of direct observation to help you… when we had the
   factory-installed two blade 13 x 7 on the boat, 1,000 rpm gave us
   5knots.
   Gordon Laco
   Surprise 426
   [1]www.gordonlaco.com

   On Jun 28, 2021, at 7:00 PM, David A. Bardsley
   <[2]davebardsley at eastlink.ca> wrote:

   Gordon,
   Thanks for the pointer.
   I've removed the PO's vetus diesel and am installing a 10kW electric
   drive with a completely new transmission.  I'm free to pick an
   arbitrary ratio to maximize (hopefully) the performance of my 2 blade
   13-8 prop.
   As you can imagine I'vd been spending a lot of time at Google
   University and on the vic prop calculator!
   Dave
   Ginseng 574
   On Jun 28, 2021 19:47, Gordon Laco <[3]mainstay at csolve.net> wrote:

   Check out Skene’s Elements of Yacht Design.  There will be information
   there to allow you to make a good estimate.
   I reckon you already know that if your boat has an Atomic IV, it has
   direct 1:1 drive.
   Gordon Laco
   426 Surprise
   [4]www.gordonlaco.com

   On Jun 28, 2021, at 6:44 PM, David A. Bardsley via Public-List
   <[5]public-list at lists.alberg30.org> wrote:

     I'm designing my drive's reduction ratio and the resource at my
     disposal requires our A30's prismatic coefficient as a part of the
   drag
     calculation.
     Can anyone share a decent figure for our craft?
     Dave
     Ginseng 574
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References

   1. http://www.gordonlaco.com/
   2. mailto:davebardsley at eastlink.ca
   3. mailto:mainstay at csolve.net
   4. http://www.gordonlaco.com/
   5. mailto:public-list at lists.alberg30.org
   6. http://www.alberg30.org/store/A30supporters.html
   7. mailto:Public-List at lists.alberg30.org