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Re: [PSUBS-MAILIST] Sound Absorption

Marten,
why dont you build a mock-up out of cardboard and find out the smallest diametre hull that you can comfortably sit in for a few hours? (or longer... !) Also - Dont knock the 'ambient' option!, They are the same total weight of course, but because the pressure differential across the hull wall is much smaller, you can get away with lower-strength (and usually cheaper) hull materials (im using perspex and fibre glass), which also dodges the need for owning or borrowing heavy machining equipment. In fact, I dont think Im planning for a single weld in my machine (except for soldering components, which hardly counts). I sort of think that ambients are the way to go for first-timers who dont have much in the way of metal machining skills like me, though I imagine that might be a contentious thing to say.. ! 

EM.


Dan H. wrote:


Marten,

My K-350 is 3 feet in diameter and luckily, I'm a little guy, 5'-6".   There
is enough room for me to operate the sub with my head in the conning tower
but it's tight when working on things inside the hull.  A hull 3'- 6" in
diameter would be better but the trade off is it's gets heavier to trailer
around.  You might want to reconsider your five foot diameter design because
of it's weight.  Remember it has to be heavy enough to dive.  If your not
going to transport it, displacement isn't as much an option.

Dan H.
----- Original Message -----
From: "Marten Liebster" <mliebster@tbteam.com>
To: <personal_submersibles@psubs.org>
Sent: Thursday, April 29, 2004 10:05 AM
Subject: RE: [PSUBS-MAILIST] Sound Absorption



Steven & Dan,

Thanks for your responses and pointers. My sub is in the concept stage,

I'm

reviewing different ideas and learning what's doable and not. I'm a fairly
big guy - 6'5" - so I'd like my pressure hull to be at least 5 feet in
diameter.

For a living I am a programmer and my experience in fabrication is purely
wood working. So the thought of through hull propulsion is a bit scary for
me. However, having hydraulic connections pass from the interior to the
exterior seems much easier to implement.

As a result, I am planning to use hydraulic propulsion, I do realize it's
not as efficient as an electric motor. This is the reason for my asking

the

original question, I'll have a pump running all the time. I anticipate

that

with not much to absorb sound and with the shape of the hull, that would

get

really annoying.

Marten

-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Dan H.
Sent: Wednesday, April 28, 2004 10:29 PM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Sound Absorption

Marten,

I haven't got me sub wet yet but the thrusters are up and running.  My

three

thrusters are in pods on the exterior of the hull.  Of course I can hear
them in the sub but they're not loud.  If you had a hydraulic pump running
all the time I'm sure that would get annoying.

I like the idea of hearing noises through the hull.  You can't see
everything around you all the time.  Hearing a noisy boat in your vicinity
before you surface is a good thing!

Besides, sound abatement materials against the hull is a place to trap
moisture.

Dan H.

BTW. "Persistence" is now yellow.  I finished the paint job last week.
Tomorrow the trailer will be blue.


----- Original Message -----
From: "Marten Liebster" <mliebster@tbteam.com>
To: <personal_submersibles@psubs.org>
Sent: Wednesday, April 28, 2004 2:50 PM
Subject: [PSUBS-MAILIST] Sound Absorption



Hi,

I am in the initial process of designing a psub, my first. The web
site

and

mailing list have to proven to be chock full invaluable information to

me.

One thing that I haven't seen much about (perhaps I'm searching on the

wrong

keywords) is that of sound absorption.

I'd imagine that a psub could be a noisy place, with all of the
motors, pumps, hydraulic and other equipment. It seems to me the hull
would

reflect

back the sound waves, it being bare metal in a tube-like shape.

Questions:
Is your psub a noisy place?
Do you use anything on the hull to absorb the sound?

Thanks,
Marten Liebster
A psub newbie