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Re: Registration
I agree that viewports are reliable. But they are a headache, requiring
periodic polishing and annealing. Avoiding those pesky single point failure
modes is important, so backup power, video and sonar are important.
Hydrophones are dirt simple, and offer a fine sensory input in addition to a
last ditch safety system. My argument is that forward looking sonar should
be the primary input for driving the boat. The stopping distance and turning
radius of a 3 ton boat far exceed the 20 foot visibility that I'm typically
going to see at the bottom of Puget Sound. If I kick up a cloud, or have a
light or power failure (!), visibility goes to zero in a heartbeat. I'd
better be able to switch to internal power and look at the sonar display in
a hurry. So why have a viewport at all? If I'm not required to look out the
bow, I can locate the pressure hull closer to the center of gravity or
center of buoyancy, and make my weights and balances easier. If I don't have
to lie prone in the hull, I can locate displays and controls more easily,
save a bit of space, and maybe enhance the comfort. :-o Joe
-----Original Message-----
From: John Brownlee <jonnie@chronic.lpl.arizona.edu>
To: personal_submersibles@psubs.org <personal_submersibles@psubs.org>
Date: Friday, January 22, 1999 7:46 AM
Subject: Re: Registration
> Two words, boys: 'power failure.'
> One of the most common single points of failure is the electrical
>system in submersibles of all kinds, statistically. Properly implimented
>viewports have a significantly lower failure rate, I actually don't know
>of any true failures in the past. Electricals are complicated with
>hundreds of components, viewports have a half dozen. There is a reason
>submersibles designed today still have viewports; if you lose a battery
>compartment or a cable gets sheared you can still see.
> It's the same reason why even the most automated subs have a means
>to blow air into the tanks under the power of the compressed air in the
>cyllinders alone. Remove single points of failure; many subs require some
>operator intervention during recovery from an abort, and being able to see
>outside helps.
> At least that's the way I see it. No pun intended, of course. :)
>
> John
>
>John Brownlee
>Lunar and Planetary Lab
>University of Arizona
>jonnie @ lpl . arizona . edu
>
>