Mirage Notes
SPEED/POWER CHART
Displacement = 30,600 lbs. 
12.5 knots 
230 SHP 
15.5 knots 
280 SHP 
18.7 knots 
350 SHP 
21.7 knots 
470 SHP 
25 knots 
610 SHP 
28 knots 
760 SHP 
The calculated speeds listed are approximate and considered accurate on the
listed displacement. Changes in displacement (or weight) will modify the
figures and will not give the speeds listed. All speeds listed are in knots per
hour. To convert to miles per hour, divide by .87. Note that the horsepower is
given as SHAFT HORSEPOWER (SHP). Since most motors are listed at BRAKE
HORSEPOWER (BHP), it will be necessary to reduce the BHP to SHP. A reliable
factor to multiply the BHP by is .70 to determine the SHP. All speeds assume
that the proper gear ratio and propeller size is used. For twin engines, divide
the SHP figure by two in order to determine horsepower required for each
engine.

Estimating Range
The following may be helpful in determining the fuel consumption and
range.
 Inboard diesel: 1 gal per hour for each 20 hp produced.
 Inboard gasoline: 1 gal per hour for each 13 hp produced.
 Range depends on speed traveled and fuel carried.
Using the above information and the Speed Chart:
 Traveling at 18.7 knots (350 shp), using a Diesel engine.
 350 (shp) divided by 20 (Diesel) = 17.5 gallons an hour.
 Fuel: 450 gallons
 450 divided by 17.5 = 25.7 hours
 At 18.7 knots x 25.7 = 480.6 knot range.
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