[PSUBS-MAILIST] No more gel-coat!

["Gary R. Boucher" <protek@shreve.net>]

     I seldom post anything but often take a look in to see what is going 
on.  Now I am truly puzzled.  First, I am not a fluids engineer, but I do 
know some facts about aerodynamics from years of studying airplanes.  I 
think you fellows are talking about turbulent boundary layer.  As air flows 
over an airplane wing the velocity of the air approaches zero as it comes 
in contact with the wing itself.  In an airplane an undisturbed boundary 
layer is very important.  This creates laminar flow down to the wings 
surface and greatly reduces drag.  One reason that the P-51 in WWII was so 
fast was that they could maintain this laminar flow well past a third of 
the wings cord.  The British gained advantage with this effect also until 
they started painting their Spitfires with a rough dull finish camouflage 
paint which disturbed the laminar flow and caused greatly increased 
drag.  Everything I have studied suggests that you want to minimize 
turbulent boundary layer flow to reduce drag.  I have no doubt that putting 
something like course sandpaper on the hull of a sub would be a massive 
mistake.
     Perhaps there is some finish that promotes a type of turbulent flow 
that is benificial but before anyone goes for the rough look I think you 
need to research this extensively.

G, Boucher