Props

Home Up Choosing a Prop Props OMC Models: 62-72 OMC Models: 73-77

 

1967 Sportsman LDFV  L.Shuster
Speed Calc



Last Updated:

22 December 2006


Boat Top Speed vs. Horsepower, Load, Altitude -- Calculator

< Calculates your top speed -- You enter horsepower, hull & engine weight, passenger load, fuel & gear load and altitude above sea level.>

Prop Pitch - Speed -- Calculator

< calculates your speed and pitch required >

Prop Workshop -- from Sherrrick

< calculates your speed, pitch, slip >

 

Stern Drive Gear Ratios for 1966 Sportsman 
(and other OMC electric stringer stern drives)

GEAR RATIO TOTAL (engine to prop): is defined as the relationship of one complete revolution of the engine crankshaft to the propeller shaft. For example: One complete revolution of the 150 V6 (HUE-14D) engine crankshaft results in the propeller shaft rotating .65 or approximately 2/3's of a turn.

OVERALL RATIO (prop to engine) : is defined as the relationship of one complete revolution of the propeller shaft to the engine crankshaft. For example: One complete revolution of the 150 V6 (HUE-14D) propeller shaft results in the engine crankshaft rotating 1.54 or approximately 1-1/2 turns.

Engine HP Model Number Upper Ratio Lower Ratio Gear Ratio
Total
(engine to prop)
Overall
Ratio
(prop to engine)
Calculated
Speed Range
in MPH:
20% Prop Slip
Engine @ 
4000 RPM
12" -20" pitch props
Distance
(in inches)
Prop travels
per
Each
Engine
Revolution
(with
12-inch
pitch)
Distance
(in inches)
Prop travels
per
Each
Engine
Revolution
(with
20-inch
pitch)
80, 90 I-4 NU 16.28 20.23 .49 2.04 13 - 21 4.6 6.7
100, 120,
I-4
(67-71 and 72, 10C) 16.20 15.23 .52 1.92 15 - 36
120,
140 I-4
CU, GU, LU, SU, VU (72-10S) 19.20 15.23 .62 1.61 23 - 38 7.4 12.4
150/155
V6 &
(140 - 73up)
HU 25.25 15.23 .62 1.54 24 - 39 7.8 13.0
165 I-6

170, 190 V8

JU, WU

(Ford)

21.19 15.23 .72 1.39 26 - 44 8.7 14.4
175 V8 (Ford) 21.18 15.23 .76 1.32 28 - 46 9.1 15.2
190 V8 (Ford) 21.17 15.23 .81 1.24 29 - 49 9.7 16.1
185/200/210/215
225/235/245 V8
TU & XU
(Chevy)
21.16 15.23 .86 1.16 31 - 52 10.3 17.1

Available 14 and 14.25-inch Propellers for the 1964 - 1977 Electric Shift Stringer.
(Click Here: for help in choosing the right prop)

Note: 1964 - 1966; 120, 150, and 200 hp models must ONLY
use
14.25" Diameter ("taper-hub") series to clear exhaust outlet.

Part No Diameter Pitch Material Mfg Blades
381296 14.25 10 AL OMC 3
382676 14.00 11 AL OMC 3
012089/PR119 14.00 11 AL MWC 3
382017 14.00 12 AL OMC 3 X(SC)
380187 14.25 12 AL OMC 3 XX
012090/PR120 14.00 12 AL MWC 3
172490 14.00 13 SST OMC 3 XX
381185 14.00 14 AL OMC 3
380074 14.25 14 AL OMC 3 XX
012091/PR121 14.00 14 AL/BR MWC 3 X
172491 14.00 15 SST OMC 3 XX
381020 12.50 16 AL OMC 3 XX
381186 14.00 16 AL OMC 3
380188 14.25 16 AL OMC 3 X
012092/PR122 14.00 16 AL MWC 3
172492 14.00 17 SST OMC 3 X
381187 14.00 18 AL OMC 3
380189 14.25 18 AL OMC 3 X
012093/PR123 14.00 18 AL MWC 3
172493 14.00 19 SST OMC 3
383287 14.00 20 AL OMC 3
379652 14.25 20 AL OMC 3
012094/PR124 14.00 20 AL MWC 3
380190 14.25 22 AL OMC 3

Presently, at 6100' ASL, my V8-Sportsman is swinging a 14.00" x 13" SST prop on 21:16 upper gears (1.16 ratio), at WOT it spins 4400 RPM @37 mph

(X indicates prop in inventory in pitches:  12",15",16",17",18)

MWC = Michigan Wheel Corporation
OMC = Outboard Marine Corporation