Submarine Basics


Early History:

    The ability of humans to live beneath the sea has probably been imagined since man first opened his eyes underwater.  However the reality of this did not occur until the early 1800's.  

    One of these early sub builders was the American engineer Robert Fulton.  In 1799 he presented plans to the French for his submarine.  The French rejected the idea but Fulton went on to build a vessel, and sea trials began in 1800.  Fulton's Nautilus was technically a success but the navies of the era were not ready for the submarine as a war ship.

  One of the most interesting submarine inventors was Simon Lake, who in 1897 built the Argonaut.  Lake along with John Holland developed many submarines in the years to follow.  With the technical demands of submarine construction in the early 1900's only governments could afford to build such vessels.  But by today's standards all of the necessary construction techniques are readily available.


How Submarines Work:

    The ability of a submarine to vary the amount of water it displaces and to resist the considerable pressure underwater allows the submarine to function.  The pressure of sea water can be estimated to be approximately 0.45 psi per foot of depth.  At 33 ft. the pressure is approx. 15 psi or what is termed "one atmosphere".  since at sea level the atmosphere around us is 15 psi each increment of 33 ft. is termed "one atmosphere".  Often the pressure of sea level is omitted and only the gage reading is referred to.  So 1 atm (33') would have a pressure of 15 psi,  at 66' - 30 psi,  at 99' - 45 psi,  at  132' - 60 psi,  at 165' - 75 psi and so on.

     One hard truth the submarine designer learns right away is the weight of sea water, which is 64 lbs per cubic foot.  What this means is that for every cubic foot of air space in a submarine there must be 64 lbs of ballast to submerge that amount of air.  This adds up quickly, especially when you start adding living rooms, bedrooms, galley.  Suffice to say amenities start to go out the window once the tremendous weight and structure is calculated.  Where as a surface vessel merely has to float upon the surface of the water there is no penalty paid for extra space besides the moderate support a boat needs.  And in the case of a surface vessel, extra weight is not a requirement except for proper balance. 


             Simon Lake's "Argonaut"   1897

      Computer image of John Holland's sub early 1900's



Electric submersible with articulating entry