What is pitch?
Pitch is the amount of twist in the blades of the propeller. It is defined as the theoretical distance the propeller will travel forward in one revolution. Thus, in theory, a 13 pitch propeller will move the boat forward 13 with each revolution. In actuality, the boat will move forward less than 13 due to slip.
The term “pitch” has both a subjective and an objective sense. Concert pitch is an objective term corresponding to the frequency of a musical note A (at present 440Hz). Using such a standard will define the pitch of every other note on a particular musical scale. For example, with equal temperament each semitone is higher or lower in frequency than the previous semitone by a factor of 2^(1/12). An octave is a pitch interval of 2:1. Many sounds with no obvious tonal prominence are considered by musicians to be of indeterminate pitch; for example, the side drum, cymbals, triangle, castanets, tambourine, and likewise the spoken word. Pitch is also a subjective frequency ordering of sounds. Perceived pitch is dependent on frequency, waveform and amplitude or changing amplitude. Numbers can be assigned to perceived pitch relative to a pure frontal tone of 1000Hz at 40dB (1000 mels) thereby establishing a pitch scale.
