RE: [PSUBS-MAILIST] Seals again

[John Brownlee <jonnie@cobweb.scarymonsters.net>]

	The question of pressure compensation is a tricky one. A lot of
the reason people are so wound up about it is that they have already built
a sub, or trusted themselves to a DPV or similar vehicle. By now we should
all know that saying that someone's sub is not well built is like telling
them their kids are ugly.
	WATCH OUT!

	For the depths psubbers consider (except maybe those past 300 fsw)
you can probably go either way. What I've seen, both in the plans to
K-boats and ROV's is that down to about 300fsw the important thing is to
do your homework about the dynamic forces across that seal. As long as the
seals, pressure compensated or not, are well put together in a properly
designed and installed thruster pod they each have merits. Busby treats
this subject, both for battery boxes and for motors. Maybe someone who
snagged a shiny new copy on eBay or from the Navy can post the plusses and
minuses in there?
	I for one am planning on using a pressure-compensated brushless DC
motor on my pile of scrap in the garage, I mean sub. :-) That's the sort
of set-up all the thrusters I've ever seen use, and they are pretty robust
at sea.

					Just my opinion,

							John

John Brownlee
Chief Systems Administrator
Scary Monsters Network
jonnie at scarymonsters dot net