Re: [PSUBS-MAILIST] OSS List

[Ray Keefer <Ray.Keefer@Sun.COM>]

Hi,

Some offhand thoughts below.


	
> From: "Dan H." <JMachine@adelphia.net>
> To: "PSUBS" <Personal_Submersibles@psubs.org>
> Subject: [PSUBS-MAILIST] OSS   List
> Date: Mon, 13 Jan 2003 23:52:48 -0500
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> 
> > OK. You have a lot of opinions. :) Ready to help compile that list of those 
interested
> > and the skills they bring to the table? A landlubber is perfectly suited. 
Furthermore,
> > you seem to grasp the situation perfectly. I don't think we need to worry 
about a new
> > server at this point, but I have a server I would offer to the cause if it 
ever got to
> > that point. What I would like to see is everyone who has expressed interest 
to either
> > post their wish-list or e-mail them to myself or you...:) So we can compile 
a preliminary
> > spec. It will probably change a bit as time goes on, but it will give us a 
place to start!
> > Please, all, spec the following:
> 
> > 1. Length
> The two place K-350 has a pressure hull eight feet long at it's maximum 
length, the center of the end caps.  That seems to be adequate for two people. 
Another half foot would be nice but not necessary. 

Eight foot is good enough to allow you to stretch out. Added bolt on
sections will be in addition to that basic length. Keep the overall
length short enough to keep the Coast Guard away. I think a boat over
sixteen feet becomes another class of vessel. I think? Any one know?
  
> > 2. Diameter
> The K-350's  hull diameter is three feet.  That's barely adequate.  Four more 
inches in diameter would be nice.  The three foot diameter isn't bad when 
sitting in an operating position but it's tough to fold yourself up to do 
anything in the hull for a any length of time.  The trade off though would be 
the extra over all weight the sub would have to displace.   A two place K-350 
displaces about 4400 pounds.  Of course, that's what it weighs on a trailer too. 
 The trailer would weigh another thousand pounds.   The toeing weight of a K-350 
on a trailer is around 5400 pounds.  

What is the displacement of a three foot four inches diameter hull?
Doing some quick math with a eight foot cylinder for simplicity
and salt water as the worse case density:

	Displacement = density of salt water * l * pi * r^2

36 inch diameter cylinder
	D = 64pounds/ft^3 * 8foot * 3.14 * (36inch * 1ft/12inch / 2)^2
	  = 3617pounds
	  
40 in diameter cylinder
	D = 64pounds/ft^3 * 8foot * 3.14 * (40inch * 1ft/12inch / 2)^2
	  = 4474pounds
	  
Diff = 4474pounds - 3617pounds = 857pounds

While an extra 4 inches might be nice, is it worth an extra 850 pounds?
	
	
> > 3. Speed 
> I haven't got mine wet yet but from what I hear from the "Salts" is that speed 
on the surface is good but submerged you don't need it.  You don't want to go 
any faster then the speed you can control to avoid hazards.  I guess it depends 
on your visibility.  Speed also has the trade off of the amount of battery power 
you have for the time you want to run.  Running fast uses up a lot of battery.

You get what you get with your thrusters. How many thrusters? Location?

More important is to have a nice speed controller so you can adjust the
speed from dead stop to fastest in fine enough steps that you don't have
to keep flipping the throttle on and off.
  
> > 4. Range or dive time
> As far as I could get with out making the battery pods so big they hinder the 
sub's movement.  The K-350 has six deep cycle batteries for the thrusters and 
two for aux power.  Lights and other things.  A sleek sub would be great but you 
almost have to put the batteries in pods for safety.  Captain Kittredge 
recommends a one hour max dive and then surface to vent the stale in a K sub.  I 
hear five hours with minimal activity can be endured, but after that, it's Iffy 
if your going to see the light of day on your own when I a sub of that size with 
no life support.  We should use life support for emergencies only.  Keep the 
dive simple.  

I see range and dive time as two seperate criteria. For an all battery boat,
and for this first effort I strongly advise going with batteries only,
the range is set by how much power the batteries can deliver. The range
you get is what you get with six batteries.

Dive time is more of an occupant issue. If you are sparing on the battery
use the real issue is how long the occupant can safely stay sealed inside
the hull. Use CO2 absorbers as an emergancy option. For normal use
SAR (Surface And Replentish).

> > 5. Safe dive depth.  
> Don't know.  The deeper the better as long as the hull 's weight doesn't get 
so heavy that it affects submerged or surfaced stability.  The K subs are 
virtually impossible to role over.  They have their weight low enough to make 
them real stable.

Kittredge was real nervous about selling his K-600 plans. He said he wasn't
quite happy with the design and felt that the added pressures at 600 feet
could get the typical amature into trouble.

I would stick with 350 feet safe dive depth and 700 crush depth. Better yet
for this first design start with 250 and 500 feet respectively.

> > 6. Cost window
> Now there's a good one.  The cost of a approved Plexiglas dome manufactured by 
a certified manufacture is the reason it took me fifteen years to get my sub off 
the ground.   I didn't want to take a chance with a dome that wasn't certified 
so waited and then decided to put the extra dollars into the K-350 which doesn't 
have a dome.  A dome would be great though.  It must have a spectacular view and 
feeling compared to my four conning tower viewports.  I like Carstan's idea of 
the cylindrical lens.  Sitting in mine now, I feel that the view in the 
direction you want to be looking would be near as good from a cylinder as it 
would be from the dome.  You need a small hatch cover view port to see when your 
reaching full submerged but you don't need much of an actual view upward.

Simple disk viewports are simplist and cheapest. Sure the view is not
as good but keep the design simple on this first project.

> 
> One thing that is a must for me is a good view downward and forward.  The K 
subs have a viewport down forward in the front of the hull.  I'm thinking I'll 
be spending a lot of time on my belly piloting the sub from in front of it, 
close up to the bottom viewport.  Especially in murky water.  If I build an arm 
for the sub, it's a must have.

Downward port would be a nice addition to a K boat. Shroud it and protect it
with a scrap poice of plexiglass so if you bottom on a rock it doesn't 
damage the bottom viewport. 

> > 7. Further comments
> A tear drop or some other great sub shape would really look nice but for a 
PSUB, I think we have to think more practical.  It has to be something that 
isn't to difficult to build.  A cylinder can't be beat for simplicity.  Most 
larger fab shops have roles that can roll the hull and any conning tower parts.  
Tank heads are available off the shelf for the hull ends.  It's best to make 
exotic shapes only as part of shrouding where it can be done in fiberglass or 
something easy to shape.  

Cylindrical hull with fiberglass shrouds where needed. Keep it simple.

> 
> Simplicity in construction is a must to keep costs down.  Most PSUBers will be 
building with hand tools, a welder, set of torches, a lathe and a drill press.  
Maybe a milling machine and plasma cutter too, but not the same shop Carstan has 
available.  Anything farmed out to a shop really adds up costs quick.  Think in 
steel, not paper.

As in paper money?

> 
> I really like Carstan's modular idea.  A bolt on aft section would allow for 
some nice options.  If bolt on becomes to impractical, maybe the options could 
be worked into the design as an either/or thing.  Like the K-350 one place and 
two place options.  Captain Kittredge just added two feet to the aft section of 
the hull.  It seems that there should be more to it then that but that's all he 
did.  I'm thinking the weight distribution should have changed a little also, 
but time will tell.

Bolt ons is an excellent idea. Need sufficient seal and radial bolts to make
it tight and solid. The added sections need to be neutrally bouyant so as
to not upset the geometry of the hull when added.

However for simplicity of this first project I would skip the bolt on
idea.

> 
> Lead acid should be the source of power.  If someone really has the ability 
and need to install a nuke plant, they also have the ability to make the 
necessary conversions.  

Lead acid is well understood and widely available at a reasonable cost.
This is the way to go.

> 
> Some guidance and construction tips would be helpful too.  That's lacking with 
a K sub.  The Captain told me he did it that way to force the builder to study 
the prints but I still think some guidance would be nice.  He had a few brief 
sheets with his K-250 model but none with the K-350.  You don't need a "blow by 
blow" but something to guide through pitfalls.   
> A good list of sources for materials would be nice too.  It would be a great 
help to a builder when working out of his area of expertise.  Constructing a sub 
includes so many fields of expertise that no builder can be proficient in them 
all.

Also with design calculations. 

> 
>  Skills..... I'm a mechanical designer but for the past fifteen years I've run 
my small machine shop.  I guess I could probably best offer help in the area of 
the practicality of design as it relate to actual construction.  The nuts and 
bolt of the project.  
> 
> Well there you have my two cents worth, spoken in fifty cents worth of words.  
Sorry!  ;-) 
> 
> Warrend, you have my vote!
> Dan H.  

A big category that was missing was the safety features. They need to be
designed in.
1. O2 tank
2. secondary compressed air source (2nd tank?)
3. CO2 absorbtion
4. Emergancy drop weight system
5. Flood valve
6. Independant scuba set to swim free after the hull was flooded

Regards,
Ray