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 Sailor's Math  

Liters per Gallon:                3.78 Liters per Gallon, 0.264 Gallons/Liter

Gallons/Cubic Foot:                7.44 gallons per cubic foot

Fluid Weights:                                                            
                               Sea Water    =    8.6 lbs / gallon
                               Fresh Water  =    8.3 lbs / gallon    
                                Diesel Fuel   =   7.0 lbs / gallon

Displacement-Length Ratios:  

Displacement-Length Ratios - using long tons (2,240 lbs), divided by the length of the waterline cubed divided by 100:  

  • Unltra-light Displacement between 50-100,  

  • Light Displacement between 100-150, 

  • Moderate Displacement between150-220, 

  • Heavy Displacement between 220-300, 

  • Over 300 is very heavy.

Hull speed (knots) = 1.34  x  square root of length of the waterline in feet.

Distance to Horizon (nm) = 1.17 x square root of height of eye (in feet above sea level) deck at about 5' above water on Creative Touch, assume 5' eye (10’ total height of eye), then 3.7 nm to horizon

Speed (knots) of wind-driven current = 3% x (wind speed in knots)

Wave speed in knots = 1.34 x square root of wavelength in feet
                (or)
Wave speed =  3.03 x (wave period in seconds)

Tide rises or falls these fractions of its range in these hours:

Change  Time Total
 1/12 1st hour 1/12
 2/12 2nd hour 3/12
 3/12 3rd hour 6/12
 3/12 4th hour 9/12
 2/12 5th hour 11/12
 1/12 6th hour 12/12