RE: Prone position.. was Re: [PSUBS-MAILIST] Carsten: Sgt. Pepper

["Alec Smyth" <Asmyth@changepoint.com>]

Hi Shawn,

We're taking a very similar tack... my internal hull diameter is 30" and
a fraction, and I'm using a sloped pad just as you describe. You can
lock yourself in place with elbows and knees, and if that's insufficient
I'm thinking of a Velcro band from the pad around my back. I didn't go
with the hang glider idea because it seemed cumbersome in the very
limited space available, plus I don't think it would work inverted.

I haven't yet gone diving as the sub is under construction, but the pad
is already built and I've tried it out in the garage... despite much
tinkering with the angle, etc. it's still pretty darned uncomfortable.

I also note the evolutions of Graham Hawkes' designs: Deep flight I has
a "purist" prone position. DF II (not built) is an "angled up prone".
And his latest design, Aviator, uses a conventional seated position.
That tells me a lot, but unfortunately I'd already started when Aviator
showed up.

I think there is a parallel to the rider's position on a sportbike I
used to own; dictated purely by aerodynamic considerations.
Uncomfortable as hell, yet the ride might be exciting enough to make you
forget it. After a two hour ride I could hardly walk, but that doesn't
mean it wasn't worth it!

If I were building a sub for moderate or low visibility water (think
Carsten) a "flyer" would not be a viable option, so I'd never even
consider a prone position. 

Cheers,

Alec


-----Original Message-----
From: Carsten Standfuss [mailto:MerlinSub@t-online.de] 
Sent: Friday, November 07, 2003 10:32 AM
To: personal_submersibles@psubs.org
Subject: Prone position.. was Re: [PSUBS-MAILIST] Carsten: Sgt. Pepper

What was it about the prone position that was uncomfortable?  My current
design is prone and about the same length, but with a 700mm-750mm
(~28"-30") diameter, a
hanging harness (think hanggliders), and a sloped chest-hip pad with
chin-rest that keeps most of the weight off the elbows and neck.
 
Warm Regards
Shawn

Shawn the answer is simple - build a 1:1 scale mockeup from unexpensive
material - in your wifes kittchen maybe. Than go in and test it so long
you want - if you build a sub according to class standards - a single 
seater = 72 hours.. 

If you find it after 3-4 hours still comfortable - maybe okay. 
In Sgt.Peppers about 2 hours is the border. (540 m diameter) If you want
to sit for some minutes in the sub - you need about a diamter of at
least 900 mm ..  

On problem on Sgt.Peppers is that you can not reach the technic near
your legs and feets with the hands.. so all technic which need control
or maintance during the dive has to be in the area of your hands.. -
thats the area were also your shoulders are.. 

hmm.. build a plywood, paper something mockeup and test it for hours..

I build a 1:1 mockeup of Sgt.Peppers and test it before I build the real
thing - but I test it only for minutes - 5 Minutes there - 10 minutes
this. That was wrong. Test it at leat so long as you wish to dive - and
than add 100 % - if you fell comfortable - okay build it.. 

regards Carsten