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Last Updated:
22 December 2006
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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 |
|
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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
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