These calculators are written in Javascript.   To run them you may have to adjust your security settings.

Hull Speed Calculator

As a non-planing boat moves through the water it creates a bow and stern wave.   As speed increases the waves get farthar apart as the bow wave is pushed ahead, and the stern wave is left behind.   Hull speed is reached when the boat is caught in between the two waves.

The formula for hull speed is HS=1.34*(square root of LWL) where LWL is length of water line.

Landfall fix

This is a form of costal navigation where the position and height of a land mark is known, such as a lighthouse marked on a chart.   When the landmark is first visable (appears above the horizon), This formula can be used to calculate your distance from the land mark, and position.   Take a compass bearing on the landmark.   Now find the Circular LOP. This is determinded by plugging two variables into a formula.   "X" is the known height of the land mark above sea level, and "Y" is the height of the observer above sea level. The formula is:   circular lop = (1.17 * square root of x) + (1.17 * square root of y).   Draw a circle around the land mark using the circular lop as the radius. Your position is the point on the circle that intersects the bearing line to the landmark.

Distance to the horizon

The distance to the horizon is a simple calculation.   The only variable is how far above sea level the observer's eye is.   We'll call this variable "eye-level".   The fromula is:   distance to horizon = 1.17 * square root of "eye-level".   If you notice this is half of the landfall fix calculation from above.   The distance is the same for all directions.

Speed converter

This calculator will convert knots to miles per hour, or miles per hour to knots.   the formulas are 1 mph=.8695652 knots, and 1 knot=1.15 mph.