T&T: T&T Prop Pitch Question

[Elliott Bray]

I was intrigued with Stephen Offutt's question so I went to BoatDiesel.com's
calculator.
At first I mixed apples and oranges. I varied hull types and then tried to
come to conclusions about the correct pitch. I was astonished by how much
gear ratio changed hp required until I though about it for a while.

Gear ratio basically ONLY effects Pitch.. (duh)

Except for a few 1/10ths of an inch, the pitch was the same for a given gear
ratio across hull types.

Gear Ratio:1             1.5   1.75  2     2.25
 Pitch for 22" prop	12.4	17.2	21.8	26.4

So, I would quess that 'Dutch Master' has a 1.5:1 gear ratio and the pitch
is correct.

OTOH.....Physics reigns!!  And I don't mind 8 kts

	Displace  LWL Engines HP each	WOT  Cruise	blades Diameter
	30000	  34.7    2      135	2200	1800	  4     22

Hull		             Average     Slow
Type                      Semi       Semi
                         Displace   Displace   Displace

--------------------------------------------------------
	Hull speed (kts)       11.8     8.8       7.9

	Power required (shp)   198     83.4      59.6

Max Performance
      Available power        262     262       262

      Power Used             198      83        60

      Max Speed               11.8    8.8       7.9

      FUEL CONSUMPTION        11.6    4.9       3.5

Cruising Performance

      Power Used             143

      Cruising Speed          10.6

      FUEL CONSUMPTION         8





****************
Elliott Bray
  wintering in Austin
M/V Letitia - Gulfstar 44 MC
  lounging in heated storage in Michigan
*************