Proper Pilotage. That branch of navigation dealing with the conducting of a ship by methods involving astronomical observations and calculations. Now termed 'Navigation' or 'Astronomical Navigation'. In Elizabethan times it meant ocean navigation.
Proper Return Port. Port to which a seaman can claim to be returned on completion of his service to a ship.
Propogation. Movement of crest of a progressive wave.
Proportional Lengths. Relative dimensions of a ship and appropriate lengths of masts and spars. These used to be tabulated thus:- Length of Ship = Breadth x 7. Main Yard=2.3 Breadth. Depth of Hold=LengthxO-09. Lower Topsail Yard ==1.85 Breadth. Mainmast = Breadth x 2.25. Spanker Gaff== Breadth. Foremast=Breadthx2-09. Bowsprit=0-7 Breadth. Mizen Mast-= Breadth x 2.