Penetrations, electrical and otherwise

[John Brownlee <jonnie@chronic.lpl.arizona.edu>]

	You know, I have to disagree on one point about the benefits of
single penetrations. 

	If you want to get ABS classed, you are going to have more than
one penetration for your controls. ABS is pretty specific that you need to
have a way to control some external systems with one penetrator gone, plus
if your batteries are external, you might want to consider this. Many
commercial penetrators/connectors can survive being sheared off without
inducing a leak in the pressure hull. If you can keep all your
penetrations electrical, great. 
	Optical sounds interesting, though if that's -ALL- the
penetrations you have, you're talking about two sets of batteries and so
on, one external and one internal. Besides, I'd have more confidence in a
commercial penetrator/connector system than my own viewports. The
manufacturers of these products can usually show a wickedly thorough
design philosophy, plus you have the added assurance that these products
are used by the professionals in manned applications such as long-term
saturation habitats and the like. 
	With regard to penetrators and connectors, there are a multitude
of high-density and multiple-gage wiring penetrators available on the
market.  Check out SeaCon, Inc. for starters. They're really big in the
ROV circuit (no pun intended), and I believe you cah find their
distributors off of www.rov.net. Just be careful about interference if
you're using a lot of electronic signal passing in those connectors. Put
your main bus feeds next to the TTL circuit for controlling your motors
sometime! What a mess! 

							John

John Brownlee
Lunar and Planetary Lab
University of Arizona
jonnie @ lpl . arizona . edu