Viewport????

[shawl@torchlake.com (Jonathan Shawl)]

"So why have a view port at all?"
Now my 2 cents worth. I agree with the need for forward and downward looking
sonar for the reasons you stated. My stopping distance for my 4500 lb sub is
about 10' when inching along the bottom at a slow observation speed. This is why
I included a strong but somewhat flexible bumper all around my sub. I would use
cameras also, in areas they would help, like checking blind areas, but unless
you have an expensive stereo optic tv system you won't get the 3D depth
perception you get from looking out the view port. The fish will miss out on the
experience also because they do react to movement inside the sub and will
sometimes try to bite at your fingers if wiggled next to the port. This kind of
experience is part of the reason why I built a sub in the first place. For me
watching fish on a monitor is a bit like watching Costeau reruns on TV.
     I know of some people that would not get into a windowless anything just
because of the psychological aspects of it, but they would if they knew they
could see out a window. Another thing I was thinking about is rescue, if stuck
on the bottom for any reason, it can help the operator inside psychologically to
see the outside help. The rescue diver looking in can determine your condition,
and the condition of the hull, Flooded or not.
In my sub, " lying prone in the hull" is quite relaxing and comfortable. I can
see out some of the view ports from a sitting position also. As far as "making
weights and balances easier" Balance is not that complicated or hard on any
design. In my sub design when I  put 2000 lb. of batteries and lead weight in
and on the very bottom of a 4500 lb sub, it had no other choice but to float
level and upright. You state, "I can locate the pressure hull closer to the
center of gravity or center of buoyancy". As far as I can figure the center of
the pressure hull is normally the center of buoyancy and gravity, until you
start hanging on the accessories. If you hang a 1000 lb. of arms and equipment
added on one end, then that can complicate things a little, but moving more lead
to the back is not that hard. To me a windowless mini sub might just as well be
a ROV.
 There are as many pros and cons as there are people in this group. If you are
more comfortable without view ports and have the equipment to replace them with,
safely, then design it that way. Its like cars, 100's of designs, some safer for
some types of driving, and others more economical to build and drive. The bottom
line... If  I design another sub it will always include at least one view port
looking upward and that will "enhance the comfort" for me even if its only
psychologically.
I think that's what puts the "Personal" in Psubs.
Thanks for reading this far down,
Sincerely, Jon Shawl

P.S. If you had a view port instead of a  tv monitor you
could have seen at a glance how long this note is without
scrolling down. Sorry, I was just trying to be funny.  ;-)

Marsee Skidmore wrote:

> 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
>