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Frequently Asked Questions

About:

Last update:	09 Dec 2005

Scope:		This page is a collection of Frequently Asked Questions

Index:

Are Picture Attachements ok to send to the alias?

Frequently Asked Questions:

        Question:

	Does anybody here know anyone who built an "AquaSub"?
	Does anybody know anything about "AquaSub"?
	Does anybody know where to get plans for "AquaSub"?

        Answer:

	Go to the main page and follow the links of:
	Sources -> AquaSub


        ( Ray Keefer 04 Dec 2000 )

        Question:

	Are picture attachements allowed in email to the personal_submersibles@psubs.org alias?

        Answer:

	Email is limited to the size of 40k.


        ( Jon Wallace 09 Dec 2005 )

	Question:

	Tell me about PSUB designs?

	Answer:

	There are two basic design approaches to submarines. 
	Ambient pressure designs and 1 atmosphere designs. 
	They both have advantages and disadvantages
	and selecting the proper type depends on your criteria.
	Primarily the deciding criteria is cost and depth:

			Ambient		1 Atmosphere
	Cost		lower		higher
			$1k-$20k	$10k-$500K
	Max Depth	shallower	deeper
			0-160 feet	0-1000+ feet

	To a lesser extent are concerns with weight and certification.


        Ambient pressure designs include wet subs and 
        semi-wet subs as well as dry ambient designs.

	In ambient pressure designs the air pressure 
	of the cabin is the same as that of the surrounding 
	water at that depth. This means the hull can be 
	lighter and easily shaped to be hydrodynamically 
        streamlined. Their hulls can be made out of fiberglass
        in just about any shape you want.

	Draw backs come in with the physiological 
	limits on the human body. The deeper you are the 
	quicker your body absorbes nitrogen. As you come 
	up you must do so carefully. If you stay down too 
	long or come up too fast the nitrogen comes out 
	of solution in your blood stream and forms bubbles 
	in your blood stream. That is the bends. Very painful 
	and potentially leathal. Use of standard dive tables, 
	same as a scuba diver uses, is a must with ambient
	pressure designs. You are also limited to 120 to 
	160 feet deep due the non-decompression limits
	on the human body. Deeper and you have to 
	decompress and have to deal with nitrogen narcoses 
        or rapture of the deep. Which is the nitrogen content 
	increasing to the point that your judgement gets inpared,
	much as if you are drunk. Also at some deeper 	
	depth the oxygen partial pressure increases to the 
	point that the oxygen in the air gets toxic.

	In 1 atmosphere designs the air pressure of the 
	cabin is kept at the same pressure as up on the 
	surface. Staying at 1 atmosphere in the cabin means 
	there is no issue with nitrogen absorbtion and 
	therefore no issue with the bends. The problem is 
	that for every 33 feet of depth you submerge the 
	surrounding water pressure increases 1 full 
	atmosphere. So at 33 feet down you have the pressure 
	of 2 atmospheres (1 at surface plus one for being 33 
	feet down). At 99 feet you would have an equivelant of 4
	atmosphere of pressure pressing on your hull. With 1 
	atmosphere inside your hull you have a differential 
	of 3 atmosphere pressing on your hull. So here are 
	the drawbacks of 1 atmosphere designs. The hull has 
	to be made strong enough to withstand the pressure 
	differential, else the hull collaspes like
	a crushed can and you die. So 1 atmosphere hulls 
	are designed and built to withstand some theoritical 
	depth over what you want to operate in.  

	Say you want a 600 foot deep operation with a 2x 
	safety factor. The sub would be designed to 
	withstand the water pressure at 1200 feet. 
	Then you want to actually test the hull to some
	point deeper then you typically will operate but
	not quite as deep as the calculated crush depth.
	The idea is to test the hull while not actually
	crushing it. A test depth to 1.5x of the typical
	operational depth is a good factor, or about
	900 feet in this example.

	If at all possible, do not be in the hull when
	proving the test depth. A flaw in a weld or in
	the hull materials can kill you. Do the test 
	unmanned.
	
	The strong hull to withstand the pressure
	differenctial translates into cost and weight. 
	Typically formed and welded out of steel or aluminum. 
	With the best pressure resistant shapes being spheres
	or cylinders with endcaps. Any streamlining for a
	better hydrodynamic shape is done by tacking on
	a streamlined superstruction to the hull. Which
	adds more weight.

	( Ray Keefer 12 Sep 2001 )

        Question:
	
	Why you are more bouyant in salt water then in fresh water?

        Answer:

	Displacement equals the amount of liquid an object displaces or moves
	out of the way when put into that liquid. The force of that displaced
	water pushing on a hull is called Bouyancy. If an object floats then
	the amount of liquid displaced weighs the same as the object and
	overall that object is less dense then the liquid it is floating on.


	Formulas:
	
	Bouyancy = volume of liquid displaced   X    density of liquid displaced
   	  (lb)                (ft^3)                         (lb/ft^3)
               	   (also known as displacement)
   
   
	or shifted around:

                         	Bouyancy
                           	  (lb)
	Displacement = ----------------------------------
   	    (ft^3)         density of liquid displaced 
                           	(lb/ft^3)   
 
	Constants:
  
	lb   = pounds
	ft^3 = cubic feet

	Density of fresh water is: 62.3 lb/ft^3
	Density of salt water is:  64.0 lb/ft^3

	Example:

	A boat weights 100 lb. How much fresh water and salt water will
	it displace? Which liquid is more bouyant?


          	Fresh Water				Salt Water
          
                  	   Bouyancy                                Bouyancy
	Displacement = -----------------        Displacement = -----------------
                  	   Density                                 Density
                  
                      	   100 lb                                  100 lb
                     = ------------------                    = -----------------       
                   	   62.3 lb/ft^3                            64.0 lb/ft^3
                   
             	     =   1.61 ft^3                           =    1.56 ft^3
             
	Salt water is more bouyant since less is needed to displace the same 
	weight.


        ( Ray Keefer 16 Jan 2001 )

	Question: 

	How is the air pressure regulated inside the 
	sub (how does it keep the air fresh). Do you 
	have to decompress.

	Answer:

	See Lifesupport

	for a discussion of air quality and requirements.

	In general it depends on the design you have.
	Either Ambient or 1 Atmosphere.

	Typically with an Ambient design, air is
	continually bled into the cabin and as the
	pressure increases over ambient water pressure
	it opens a check valve and gets dumped outside
	the hull.

	With a 1 Atmostphere design there are a few
	approaches. 
	
	1. Come up and ventalate regularly with outside air.
	
	2. Use CO2 absorbant and bleed in replacement O2 (oxygen).

	3. Use CO2 absorbant and bleed in replacement air. 
	   Problem is that in addition to the oxygen in the air
	   you are also adding more nitrogen.
	   The air pressure in the cabin increases.

	4. Just bleed in more air. However the
	   air pressure in the cabin increases.

	( Ray Keefer 06 Nov 2001 )

 

	Question:

	I was wondering if you could run a combustion 
	engine under water?

	Answer:

	Depends. There are a lot of trade offs 
	and issues. I'll summerize.

	Due to the fact a combustion engine to run 
	under water needs air, actually oxygen, a supply of 
	air needs to provided.

	If just under the surface then the air can be 
	provided by a snorkel system. This is an air intake 
	pipe that sticks up out of the water with some 
	sort of valve that will not let water in if it's 	
	tip dips below the surface of the water. Problem 
	with dipping below the surface of the water is 
	that the engine is still running and sucks the 
	air out of the interior of the sub. The 
	decompression can be painful on the ears. The 
	engine should suffocate before you but overall 
	it is an unpleasant business.

	If you seperate your main cabin from the engine 
	cabin you can alieve yourself of the decompression 
	effects on your ears. You might get a run time of a few
	seconds to maybe a minute. I believe that is the 
	way the Bionic Dolphin works.

	Another concern would be if you had a 1atm hull 
	and decompressed the interior of your engine 
	compartment then the pressure differential 
	between inside and outside your hull will 
	increase. The effect would be the same as diving
	even deeper. Perhaps to the point your hull collaspes.

	You can provide air via scuba tanks. My 
	understanding is that a typical lawn mower 
	type engine (1-10HP) will drain a scuba tank 
	in under ten minutes.

	Much more elaberate system, thus more expensive, 
	is to recycle the air and add oxygen that was 
	used up. This process absorbs CO2 and CO out 
	of the air and squirts a fixed amount of oxygen 
	back in. You get longer endurance then the scuba 
	tank but at much more cost and complexity. The Japanse
	are deveoloping an underwater robot probe 
	that uses this system.

	Make sure you use a diesel engine. I know gas 
	engines are much more available but gas fumes 
	are explosive and you have to deal with United
	States Coast Guard regulations in regards to 
	ventelation. Which means more holes and valves 
	in your hull. The early submarine pioneers
	immediately did away with gasaline engines in 
	their designs back in the 1910's as soon as 
	reliable diesels came onto the scene because
	diesels do not produce explosive fumes.

	The best current level of technology available to the 
	average home building is a diesel-electric drive. 
	Diesel on the surface and electric (batteries) below. 
	Still this has a lot of details.

	For instance. You can go battery only for both 
	surface and submerged. This is the least complex 
	method. But how do you recharge the battery? At the dock?
	Most PSUBS use this approach, batteries and electric motors.

	Does the diesel drive a generator? Drives the 
	prop direct? Or is the prop driven from an electric 
	motor. Does the diesel drive an air compressor?
	On and on....

	One caution is to watch the fumes. Even diesels
	will produce the deadly CO (cabon monoxide)
	gas the will kill you.

	( Ray Keefer 22 Aug 2001 )

        Question:

	What kind of controller arrangement does everyone have? (A 
	simplified version of this question would be "What does you 	
	dashboard and steering wheel look like?")

        Answer:

	I use two arcarde joysticks in one box to control all 
	four thrusters and one orginal Minkota-controller for 
	the main engine in Sgt.Peppers.  But this depends on 
	your own expirence - a EMM (electronic-mad-man) will control 
	his sub with a laptop, a steel-man with some kind of gear 
	and maybe long steel pipes etc..  Cssx will be a electric 
	aircraft steering system for the rudder and a simple 
	four step switch four the electric main engine. For the diesel 
	and the side rudder will be a second station as joystick 
	which I can give up to the hutch to the outside sail to 
	control the sub on the surface or inside the harbour. 
	( Sgt.Peppers joystick-box can be also use from outside the 
	hatch - the cable is a little longer than its needs..) 

	( Carsten Standfuss 18 Sep 2000 )

        Question:

	I have noticed that other subs that I have seen seem to 
	be unusually heavy as well as unusually expensive (such as 
	one sub that weighed 3.5 tons, was 8 feet long and cost 
	$100,000), why is this?

        Answer:

	Depends on your specification. How many person, how long, 
	speed, range, diver lock out or not? 

	For a Psub a good size is a two persons steel sub which 
	can be driven on a trailer behind your pickup. Around  
	2 tons should be fit the most specifications. Sgt.Peppers 
	with only 0,65 t is clear a midget version of a midget. 
	I was last week in the museum and listen to a guy which 
	explain to his child that it is maybe only a model of a sub...

	A Kittredge size sub should be possible for about $15,000 
	for the material and some contracted working hours. Sgt.Peppers 
	material was around $7,000 including the trailer and the 
	battery charger. CSSX will be play in a other class..

	If you have no expirence with steel - maybe work for one/two 
	weeks as help-mate in a metal-shop (during your free-time 
	or holiday or payed). [or take some metal shop or welding
	classes - rk ]

	Pat is right - steel is inexpensive and simple to handle. I 
	can use both steel and reinforced GRP/GFK [ fiberglass - rk ]
	and I like the steel. I calculate with $0.50 for each Kilogram 
	(1/1000 t) steel if I work self and with $1.20 for each 
	Kilogramm made ready to use/build in from a metal shop. For 
	stainless steel it is much more - about $3 if you work 
	yourself - but welding needs much more expirence. 

        ( Carsten Standfuss 18 Sep 2000 )

	The costs to contract a builder to produce a Kittredge designed 
	sub starts around $100,000. The reasons cost are so high are due
	to labor costs, liability insurance, and to a lesser part the
	materials. If the hull needs to be certified then you can easily
	double the costs for dealing with a Certification agency you
	need much more paper work, weld and metallurgical analysis,
	and pressure testing.

	( Ray Keefer 04 Dec 2000 )

	Question:

	Could anyone attempt to build their own PSUB?

	Answer:

	I am a firm believer that if any one wants to 
	do something they can. Depends on attitude and 
	determination. More practically when getting 
	into a hobby or field you don't know anything 
	about you have to do your homework. With
	a personal submersible you can kill yourself by 
	over looking a minor detail.

	So yes anyone can do it, but they have to approach 
	the project carefully.  Someone who rushes in is a 
	fool and is going to get hurt. One of the main
	points of this web site is to caution would be
	PSUBers to be careful.

	At a bare minumum I highly recommend as a starting 
	point is that anyone who wants to build a personal 
	submarine get scuba certified. During scuba 
	certification the issues of human physiology and 
	water pressure issues are covered. Plus they can 
	see what's under water with relatively cheapness
	($200 - $500) and be able to decide if this is 
	the kind of thing they really want to put effort in.

	After scuba certification, welding and machining 
	come in useful. A visit to your local community 
	college is a good learning plan. Even if you 
	decide not to do those steps yourself you 
	have some background to make sure the guys 
	you hire are doing the job right. 
	Again a mistake can cost you your life.
	It doesn't matter who made it. You are dead.

	( Ray Keefer 21 Sep 2001 )

        Question:

	What is a reasonable dive depth?

        Answer:
	
	For an 1 atm PSUB between 0 feet and 1300 feet depending on 
	want do you want to do with the sub and how much of a sub 
	you are willing to pay for. Over 1300 feet everything gets 
	very expensive including the pressure hull. For a private 
	pleasure sub without a real operational need, used just for 
	fun, 300 feet should be okay. For exploring wrecks or sea
	bottom 600 feet is a good limit.

	Up to 300 feet you can use standard valves and equipment 
	from the next harbour-shop. CSSX will be 820 feet 
	because this is the area I think divers will work in within 
	the next 2-20 years and also the area of the continental-shelf.

	For an ambient sub, 130 feet for most divers and 160 feet
	for advanced or mix air divers.

	( Carsten Standfuss 18 Sep 2000 )
	( Ray Keefer 04 Dec 2000 )

        Question:

	What is a reasonable dive time for a Psub?

        Answer:

	Less then one hour for a Kittredge sized PSUB if no CO2
	scrubbing system is in use. 

	If a scubbing system is in use then it depends on operator
	endurance, battery power, CO2 scubbing chemical, O2 supply,
	air supply, head facilities and food.
	
	A resonable dive length in a PSUB is 2-4 hours (my guess).	
	After that the human factor will kick in and unless you have
	enough room to stretch and stand you will get tired of
	sitting. Stay too long and sanitation issues will have to
	be delt with. Food can be sandwiches and a thermos of hot
	drink.

	How long battery power lasts depends on usage. How fast
	you run your PSUB and how much equipment you have to power.
	This is known as Power Budget.

	Air and O2 usage depends on how much you are breathing.
	Since you want an nice emergancy buffer in breathing gas
	these items shouldn't be the limiting factor in regular
	dive times. A buffer of 72 hours is a good minimum for
	emergancies on top of your regular dive time.

	( Ray Keefer 04 Dec 2000 )

	Question:

	Can I use fiberglass as a pressure hull material?

	Answer:
	
	Hey Guys,
	I worked in the fiberglass industry for some time
	as a plant foreman in a storm shelter manufacturing
	facility. As a general rule, one can expect the tinsel
	strength of standard composites to be 15 times that of
	concrete, and 3 times that of mild steel. In
	compression, the advantage is less. About 1:1 with
	mild steel, and 4-5:1 over concrete. This is by
	WEIGHT, not by thickness. The chance of making a
	mistake in fabricating here, for anyone not VERY good
	with these materials, is quite high. It is a hard
	media to work with even if you are experienced with
	it. Steel is SO much more forgiving. Also, composites
	that are damaged, even minor amounts, are virtually
	impossible to repair without leaving an uneven flex
	and compression area in the structure. The problem
	with that, I hope, is obvious. I for one think metals,
	at least for p-subs, is the cheapest and easiest way
	to go. Maintenance and monitoring are also much
	simpler. One needs ultrasound or MRI types of NDT rigs
	to inspect composites for integrity. 
	Dewey

	( Dewey Mason 08 Nov 2001 )

        Question:

        I am trying to get some info on the submarine that was often seen 
        in the old Flipper TV series. It was a dry type , carried 2 or 3 
        people, orange color [I remember yellow - rk] , had  2 large  
        oval shaped front windows, 4 porthole type 
        windows on sides and one oval window at rear. It had one top hatch and , and 
        one model was seen that was white and had an escape hatch which allowed 
        entry/exit under water via ambient pressure hull.  It was also seen in the 
        movie " Hello Down There " starring Tony Randall which I saw back in 1971.  
        Do you know the name of this sub, its whereabouts and where I can contact the 
        owner?   I'm working on a sub design for some time now and  it was a 
        magnificent design ahead of its time.

        Answer:

	Just so happens I know the approximate whereabouts of the sub in question. It 
	is more or less dead center between Bimini and Miami at the bottom of the 
	Gulf Stream. Jordan Klein owned it, and worked with Ivan Tors during the 
	Flipper and other television projects. The sub was dropped on deck during a 
	recovery one day toward the end of filming on the Primus series (short lived, 
	Peter Brown starred). The hull was pretty badly bent underneath, so to 
	celebrate, they shoved it over the stern on the way home and toasted its 
	demise. That is the one with the oval front and back windows, by the way. I 
	think the other one wasn't a real sub, but a mock-up, and has probably gone 
	the way of the do-do as well. Jordan told me this story himself, when I was 
	in Miami about 500 years ago to purchase an Amersub 300 from him. Sorry, no 
	happy endings.
	Best Regards,
	Vance Bradley

        Question:

	How should the dome/hatch be sealed?

        Answer:

	The dome ring or hatch inner suface has a grove machined into it
	to mate to the pressure hull. In this grove is
	an o-ring or rubber ring. The dome or hatch closing mechanism needs
	pull the dome or hatch tightly against this ring to create a seal.
	Once submerged the water pressure will hold the dome or hatch
	closed on 1 ATM PSUBS. For Ambient PSUBS the closing mechansim will
	have to continuely hold the hatch shut.

	The closing mechanism is usually a hinge mechanism. Usually spring
	loaded in some way to aid the operator in lifting the weight to
	open and close the hatch. 

	The clamping or dogging mechanism can be of two types. One type
	has levers or wheels on both sides of the hatch so the hatch can
	be operated from both sides. However on an 1 ATM PSUB keep in mind
	that the differential pressure of outside the PSUB and inside the
	PSUB will effective keep the hatch closed. From the inside
	the hull the air pressure will have to be equalised or flooded
	to be able to open the hatch.

	The other type of locking mechansim recoginises that the
	hatch will have to be opened from the inside any way. It 
	consists of eyebolt and nut that pulls down the hatch
	closed.

	One word of warning. If there is an over pressure in
	the interior of a 1 ATM PSUB at you surface the
	hatch or view ports could unset and let enough
	water in to sink your sub. An over pressure valve
	that will let excessive air pressure out will
	protect against that.
	
        ( Ray Keefer 04 Dec 2000 )

        Question: 

	Electric motors are rated in pounds of thrust. How do you
        figure their horsepower?

	Answer:

	This has always irritated me; we go off to buy an electric trolling
	motor of a certain horsepower, only to find that some technological
	terrorist has rated them in pounds of thrust.
 
	Wandering through some old books, I think I found a way to beat hte
	problem.  "The Marine Engineer" of July 6, 1906, has an article on
	"Propellors."  Int those days, a propellor was anything that propelled a
	boat or a ship, so the article includes interesting stuff about paddles
	wheels and pumps.
 
	The formula on page 575 follows as best I can render it:
 
	Pounds thrust = (horsepower * 33,000)/(pitch * rpm)

	I should work up a table.  What's tjhe rpm and pitch of some trolling
	motors?
 
	Mike Holt





	Hi Mike - back from the boat show

	I test your formular with the factors I just use 
	for the propellor I have allready bought for CSSX. 
	According to my Propellor diagramm 
	(Wageningen B4/55) I get : 

	1.) with Diesel : 
	Horsepower on surface (shaft):  113 HP
	Pitch (given)    	     :  2,76 foot
	rpm			     :  400
	thrust at 8.8 kn : was 1,31 t or 2888 lbs

	2.) with electric motor : 
	Horsepower on surface (shaft): 38,5 HP
	pitch the same as before
	rpm			     : 275
	thrust as 5,3 kn : was 0,64 t or 1410 lbs

	with your formular I get : 

	Pounds thrust = (horsepower * 33,000)/(pitch * rpm)
	      	= (113 x 33,000) / (2,76 x 400)  
              	= 3378 lbs (117 %) 

	or electric   = (38,5 x 33.000) / (2,76 x 275) 
              	= 1674 lbs  (118 %) 

	I looked in my sheet for medium power were I have a figure
	with 99 hp - rpm is 375 and thrust is 1,21 t or 2667 lbs
	with 8,3 knots. 

	and with the formular : 
	      = ( 99 x 33000) / (2,76 * 375) 
	      = 3156 lbs ( 118 %) 

	the maximum Propulsion force of my existing used          
	Proppelor with this Hull/speed and diamter
	is 56 % but a custom made new one should be work 
	with this given Hull/speed and prop.diamter with 
	up to 61% (109 %).  

	To get my tables in line with your "Formel 1906"
	the proppelor must have about 56 % x 118% = 66 % . 

	So the formular is not to bad - maybe just a little 
	optimistic. Should work with aircraft style propellor
	with 2-3 long small blades and a blade area under 50%.  
	Diameter maybe bigger than 50% of the hull diamter
	and /or lower horsepower and rpm. 

	Carsten

	Question:

	I was wondering how you cut and weld a propane tank. 
        I've been told if you try to weld or cut propane tanks 
        they could explode. Any info is greatly appreciated

        Answer:

        Please read Propane Tank Hull.

        If you are cutting into a used propane tank, yes, it 
        might explode. Propane is combustible and with the right
        amounts of oxygen, explosive.

        If you really want to use a propane tank the best way to go
        is to use a new one. A new propane tank comes from the factory
        with an inert compressed gas in it. They use inert gas
        for safety and the pressurization. Safety because an inert
        gas does not explode. The pressure is to keep any moisture
        from entering the tank and rusting the tank from the inside.

        Another benefit of a new propane tank is that it has not seen
        any wear and tear, extended outdoor exposure, and possibly
        any bad bangs or bumps. But even with a new tank you can't
        ever be sure about the bangs or bumps.

        ( Ray Keefer 01 Nov 2001 )

	Question:

	How do I join the discussion group?

	Answer:

	The subscription process is a two part process. 
	First part is the initial request. Which is an email sent to:

		majordomo@psubs.org

	within the body of the e-mail you put:

		subscribe personal_submersibles

	majordomo@psubs.org will respond by sending you a coded message.
	The second part of the subscription process is to send back to
	majordomo@psubs.org the coded part of the message. This proves that
	you, from your current e-mail address, did indeed want to subscribe.

	As an alternative you can follow the links:

	http://www.psubs.org/  ->  
	List Server Discusion Group Email Alias List  ->
	Subscribe Manually

	( Ray Keefer 27 Nov 2000 )

	Question:

	How do is quit the group? I was dumb and didn't archive the
	joining subscription mail that had the details in it.

	Answer:

	To unsubscribe from the discussion group send mail to:

		majordomo@psubs.org

	in the body of the mail put:

		unsubscribe personal_submersibles

	( Ray Keefer 27 Nov 2000 )

  
        Question:

        How do I submit pictures to the PSUBS web site?

        Answer:

        Send pictures to Ray Keefer

        Prefered picture format is jpeg with file names 
        in the following format:

            lowercase letters
            no spaces
            .jpg extension

        Please send in thumbnails of each picture. Prefered
        picture format is jpeg with file names in the following
        format:

            lowercase letters
            no spaces
            _tn.jpg extension

        Information to include is:

            builder name
            owner name
            specifications of sub
            when built
            Descriptive caption for each picture
            Contact info [if you want others to be able to contact you]
            Where picture taken
            Date picture was taken and initials of who to give credit to

        Time to web site is dependant on bandwidth. Web site maintenance
        is done as a hobby on the side. Sometimes pictures go up the same
        day as received and sometimes a month later. If not in two weeks
        send a followup email to Ray Keefer.

    UPDATE:
    ======

    14 Jun 2005

    The best alternative is to use the Moki picture exchange 
    at http://www.prismnet.com/~moki/subfiles.html. The 
    instructions from that web site are:



    To post: Send picture text and attachments to moki@prismnet.com
    Subject: PSUBPICTURE ADD This is a drawing of ....

    To remove: Subject: PSUBPICTURE REMOVE This is a drawing of ....




    Once you submit picture just let the group know that they are there.

    Regards,
    Ray

	
	Question:

	How/when did psubs.org start?

	Answer:

	Four guys met on the rec.boats news group and 
	started talking in private email around the 
	summer of 1996. 

	I took the gems of the conversations and started 
	a web site.

	Soon the content of the site overwhelmed my meager
	20MB allotment with my ISP and Jonathan
	Wallace graciously offered to host PSUBS.
	We have been www.psubs.org since February 11, 1997

	Since then growth has been by word of mouth
	and hits from search engines from PSUBers
	looking for a home.

        In September 2001 the site averaged over 10,000 hits 
	daily from 79 different countries.
        The interest is out there and every year we grow.

	( Ray Keefer 07 Nov 2001 )

        Question:

	How do I get started in building my dream sub?

        Answer:

	Use a plain white paper and a pen. 
	Write down: 

	- Points the sub must fullfill
   	(for example : 2 Person)

	- Points the sub should fullfill
   	(for example: under 9999 Dollar)

	- Other points not real nessesary but also nice. 
   	(for example: ready in 3 months, colour pink) 

	If you have this list, show them to the group..

	You can search the Psubs Picture Gallery
	and the Picture Gallery to get first idears 
	and impressions. 

	The archive files will help with more details. 

	Here on the group are some experts for different
	types of questions like : electronic, viewports, 
	general layout, steel, GRP, tools, adresses etc. 

        ( Carsten Standfuss 07 Dec 2000 )

	Some basic questions to ask up front:

		Ambient	or 1 ATM
		Wet or Dry
		Depth
		Distance
			- sub can travel on surface
			- sub can travel under water
			- sub is hauled to remote sites
		Size
		Submerged duration (time)
		Weight
		Number of people	
		Primary tasks
			- research
			- sample collection
			- photography
			- wreck diving
			- recreation
			- tours
			- remote arms
		Safety factor/buffer
		Safety features
			- drop weight
			- flooding
			- power to surface
			- secondary air supply
			- CO2 scrubbing
		Air quality
			- CO2 scrubbing
			- O2 tanks
			- none
			- air tanks
			- secondary air source
		Communications
		Size of support crew
		Surface support ship/boat
		Occupants sitting, prone, combination
		Battery only
		Diesel powered on surface
		How batteries are charged:
			- on beach/dock
			- on board
		How air tanks are filled:
			- on beach/dock ( at Scuba shops you need to be
			  a Certified Diver with a C card )
			- on board
		Trailerable
		Steel, Aluminimum, Fibreglass (GRP), Titanium, ...
		Skill sets you:
			- have
			- need
		Skill sets:
			- welding
			- metal cutting
			- fiberglassing
			- plexiglass working
			- math
			- drafting
			- diving
		Cost limit
		Time limit (to build)
		Maintanence:
			- time
			- effort
			
	Sources of knowledge:

		Get books listed in the Booklist and read and study.
		Get Scuba Certified.
		Learn to weld.
		Read archive.
		Ask questions.

        ( Ray Keefer 07 Dec 2000 )

	Question: 

	I am very impressed with your sub, and am considering building one myself.
	I would love some more details.  What thickness is the pressure hull,
	and tell me about the propulsion system? If you don't mind.

	Answer:

	Said to say, I have yet to build my own sub. Some day. Till then
	the PSUBS site is dedicated to those who are or have built subs.

	( Ray Keefer 13 Nov 2001 )

	Question:
	
	Does anyone know anything about using jets from a jetski 
	to propel the sub or is this totally new territory?

	Answer:

	The efficency of a jetski drive is lower than a propeller drive 
	at low speed, but for a high speed sub it can be usefull. 
	Cousteau use some kind of water jet pump nozzels in his early 
	flying saucers. But listen there is no jetski drive
	on the market with a high-pressure proof seal on the axis to keep
	sea water out.  	

	( Carsten Standfuss 18 Sep 2000 )

	Jetskis drives were discussed at one point, see archives. A few
	issues are:

	- need high power energy source to power a jetski drive. Typically a
	  PSUBS using battery power does not have the energy for an extended
	  operating time.
	- No air compression effects. A jetski on the surface sucks in some
	  air which is compressed. Then it expands upon expultion with
	  an added thrust effect. In a PSUB the air will have to be carried
	  and bled into the jetski. 
	
        ( Ray Keefer 01 Dec 2000 )

	Question:
	
	Is a PSUB usable in lakes or in the sea?

	Answer:

	Both. Just have to take in account the differenece 
	in water density of fresh water and salt water.
	When used in salt water a given hull displacement will
	need more ballast to fully submerge.

	( Ray Keefer 21 Sep 2001 )

	Question:

	Do you need a license?

	Answer:

	Not really.

	As a powered vehical a sub needs to be registered 
	as a boat. Each state differs but generally a 
	personal submersible is considered a power boat.

	The pilot himself is not licensed. Why would he be? 
	Why does one of the first questions that is ever 
	asked about this hobby is, do you have some kind 
	of approval from your government?

	However if you want insurance for your 1 atmosphere 
	design then your hull must be certified. No insurance 
	company will touch your sub without certification.

	Certification is an approval process from one of 
	the great shipping companies of the world. Such as 
	the American Bureau of Shipping or Lloyds of London.
	They set out a stringent certification process 
	where each chunk of steel you use has to be 
	certified with metalurgy and heat treating. 
	Welds have to be done and checked under regirous 
	requirements. The design has to be submitted for 
	approval before the start of construction with all the
	computations and design details. The the certifying 
	company comes out to see the sub under construction 
	at key points of assembly and witnesses the
	test dives. Then from then on the hull has to be 
	recertified each year with a complete maintenace 
	log book and dive book being maintained. The
	certification process is all paid by the builder, 
	including the time and travel costs of the certification 
	agent, and as such can often cost more then the actual sub!

	If so expesive then why get certified. You have to 
	if you are taking on passengers, want to work for 
	an University or scientific orgainization of
	some sort. They won't touch you without 
	certification and insurance.

	( Ray Keefer 21 Sep 2001 )

        Question:

        How much space does the life support
        system take up (O2 tanks, scrubber, etc.)?

        Answer:

        You need at least ~0,25 Liter/minute O2 each person

        According to the rules (GL 1988 Chapter 2 submersibles)

        - O2 is stored in two independable storage groups
        - best storage place is outside the hull

        - minimum lifesupport time for one-man subs should be 72 hours
        - minimum lifesupport time for small subs should be 96 hours
        - minimum lifesupport time for autonomus subs should be 168 hours

        So for a one person sub the O2 storage requirements should be:
        72 hours x 60 minutes x 0,25 Liters = 1080 Liters
        1080 divided by a storage pressure of 220 bar = 4,9 Liters
        4,9 divided by two groups = 2,5 Liter each bottle.

        And for a two person sub:
        96 h x 60 x 0,25 = 1440 Liter x 2 persons = 2880 Liter
        2880 / 220 = 13 Liter / by two bottles = 6,5 liter each.

        The CO2 absorber depents on the used material but
        the general rules are:

        - CO2 partial pressure should be between 0,005 bar - 0,01
          bar each time.
        - CO2 production of each person should be calculate with
          20 Liter/hour for each person at 20\260C and 1 bar atmosphere.
        - At the end of the O2 run time the CO2 pressure should be
          under 0,02 bar inside the vessel

        Without O2 support the air inside your hull will last you
        about 20-60 minutes depending on the size of your pressure hull.
        You can test this time on your finished pressure hull very easily if
        close the hutch with you inside (which should be possible
        to open from the outside) and somebody outside.

        Starting the clock and wait - if the headeages get to high
        you have CO2 poision and this last air reserve is over.
        If you fall in coma your wife/friend/girl
        should open the hutch.. Time in Sgt.Peppers was 40 Minutes..

        Keep in mind that the objects, including your body, inside the
        pressure hull reduces the internal air volume.

        I think a scuba rescue system should be also in each
        PSUB for each person..

        ( Carsten Standfuss 18 Sep 2000 )

	Question:

	What is the basic design layout of a Main Ballast Tank?

	Answer:

	On the simpler PSUBS they are controlled manually. 

	The top of the ballast tanks are piped into the hull 
	where the valves are. From one valve, the vent valve,
	a second pipe goes outside the hull for venting 
	the ballast tank. The operation is to manually 
	turn the valve open and the ballast tanks 
	flood as the air comes up the pipe, pass 
	the valve, and out. To work the valve and 
	exhaust piping have to be arranged higher then 
	the top of the ballast tank so are 
	usually located in the conning tower.

	To blow the tanks dry the first vent valve is closed
	and a  second valve, the blow valve,  is piped 
	from your compressed air (HPA) source and tee'ed 
	into the pipe from your ballast tank. The HPA
	may be reduced to just a few 100 pounds per
	square inch over the ambient water pressure.

	As the air is introduced into the piping it
	flows into the ballast tank and forces the
	water out the flood hole.


                               | <- vent pipe
                          _____|____
                          |    |   |
                   _______|____O   |<- hull/conning tower
                __|__     |  |     |
               |     | ^  |  O     |
               |     | |     |
               |__ __| |     |<- HPA       O = valves
                       |
                ^ ^    |____pipe
                | |____ flood hole
                |______ ballast tank

	Safety concerns are:

	1. The piping inside the hull needs to be able to 
	   handle the pressure differential between the 
	   outside ambient pressure and the inside 1atm
   	   pressure. Else a pipe could burst, the interior 
	   floods, the hull gets more negatively bouyant, 
	   sinks and you die.
  
	2. Each hull penetration of a pipe should also 
	   have a stop cock valve just inside the hull. 
	   This is in case a valve or pipe springs a 
	   leak. Allows you an opportunity to shut it off.

	3. The high pressure air needs to be reduced 
	   from the 3000lbs/cu in its tank to some 
	   acceptable intermediate pressure that is 
	   50 - 200 lbs/cu in over the ambient pressure. 
	   Else you could burst pipes, over pressurize
   	   your interior, pop out your view ports, 
	   flood, sink and you die.

   	So reduce your HPA and/or beef up the piping 
	and valves that you use.

	( Ray Keefer 02 Sep 2001 )

        Question:

	Can the gas in the ballast tanks be allowed to just bubble 
	off (vent) into the water to sink and then be replenished 
	from a air, scuba, CO2 cylinder or other gas tank
	or should there be a compressor to pump the gas from 
	the ballast tanks into a  pressure vessel onboard?

        Answer:

	Just bubble outside - is the normal way, replenished from 
	a air tank, which can be filled with a normal scuba-compressor. 
	The compressor should be onshore on smaller subs. Bigger subs 
	have them inside but this make only sense in combination 
	with a diesel. There is no reason to have a compressor on 
	board of a electric-only driven sub. You loose the space for 
	the compressor and  additional batteries. Putting a bigger pressure 
	bottle to the sub is much simpler and more safe. CSSX will only 
	use a small amout of air to start blowing the ballast tanks. 
	If the submarine is surfaced with just the sail the diesel 
	will run and blow the tanks empty with his exhaust gases to 
	safe compressor run time.  

        ( Carsten Standfuss 18 Sep 2000 )

        Question:

	If I can't get a copy of "Manned Submersibles," what 
	other book(s) can I use?

        Answer:

	"Manned submarines" is a very good starter. "Jane's 
	Ocean Technology 1978" is also a good source. Some 
	books about simple metal technology and Physics will also help.

        ( Carsten Standfuss 18 Sep 2000 )

	Go to the main page and follow the "Books" link.

	( Ray Keefer 04 Dec 2000 )
        

        Question:

	Where is a good place to put the motors, inside the main 
	hull or outside in a secondary hull?

        Answer:

	Depends on the design. Sgt. Peppers for example has all 
	5 motors outside for the reason I wanted a sub with a 
	small displacement. Small displacement means a small 
	pressure hull. CSSX for example will be the main engines 
	and most equipment inside because of maintance the 
	motors with the sub in the water. In General: 

	- Electric thrusters outside
	- non-electric main engines like diesels inside. 

	In smaller boats with only a electric main-engines maybe outside. 

        ( Carsten Standfuss 18 Sep 2000 )

        Question:

	I am new to the news group. I sent mail and no one responded. Am I just
	a nobody peon you PSUB gods simply ignore or didn't you see the mail.

        Answer:

	Sorry, this has happened many times.

        While some of us may be PSUB Gods. The truth of the matter is that 
	we are all busy with our active lives and sometimes don't realize a 
	new guy is trying to get started. Please don't take it personally, it is
	our nature to be very busy. 

	Just introduce yourself a second time, tell us we haven't noticed you,
	and we usually fall over ourselves welcoming you in.

	Question:

	Could PSUBS become a popular hobby?

	Answer:

	Could if the liability insurance lawyers don't 
	get involved. But one accident and they will and 
	as an industry it will be destroyed like the private
	aircraft industry was.

	With large scale mass production techniques two 
	man ambient designs could be made for $5,000 
	each commercially. 1 atmosphere designs for maybe
	$20,000 each.

	( Ray Keefer 21 Sep 2001 )

	Question:

	I have a old propane tank in my garden, can I use it to build
	an inexpensive sub? 

	Answer: 

	The general consensous is that while in theory you can use
	a propane tank as a hull you have to be very careful and know
	exactly what you are doing. A used propane tank is a hull of unknown
	material, of an unknown temper, has gone though an unknown 	
	amount of abuse, is in an unknown condition and may even still have
	propane in it! It is better to use a new propane tank but even 
	that is dangerous because it is made of an unknown material. 

        Look at the archive files under the following Headlines..
        "Propane tanks" or "Obtaining Propane tank" etc. 

	( Ray Keefer 27 Nov 2000 )

        Question:

	How are the things that need holes in the hull made so 
	that they don't leak or compromise the safety of the sub?

        Answer:

	Hmm... Let me think ... one hole for each motor cable, one 
	hole for VHF Antenna, two holes for main battery cable, 
	two for the lamps, one for the drop weight release, one 
	big one for the front window, one for the entrance, 
	5 for the ballast tank-air-out/in pipes, 2 for the regulator, 
	one for the snorkel, about 21 holes in all for Sgt.Peppers. 
	Most for cables. There are some good description in the book
	"Manned Submersibles". All holes tighted by different design of 
	o-rings and gaskets. 

	( Carsten Standfuss 18 Sep 2000 )

        Question:

        What is occupation the typical occupation of a PSUBer?

        Answer:

	PSUBers come for a cross section of our world with one commone
	interest in PSUBs. As a result we have a wide variety of 
        occupations:

		Computer Engineer, software
		Computer Engineer, hardware
		University Professor
		Farmers
		Professional Submersible Pilot
		Professional Submersible Designer and Builder
		Hobbiests
		Scuba Divers
		Web site owners
		Marina Owner
		Way Cool Hawiian Nemo
		Machine Tool Operators
		Welders

        Question:

	What does that number mean?

        Answer:

	Useful units and metric Conservation Factors

	LENGTH

	1 inch (in/")		= 25,4 mm
	1 ft			= 0,305 m
	1 yard			= 0,914 m
	1 mile			= 1,609 km
	1 sea mile (sm)		= 1,8531 km
	  [ nautical mile ]

	VOLUME
	
	1 cubic inch (cu in)	= 16,387 cc
	1 cubic inch (cu in) 	= 0,016 liter
	1 cubic foot		= 0,028 m3 or 28 liter
	1 Imp pint (pt)		= 0,568 liter
	1 US pint (pt)		= 0,473 liter
	1 imperial gallon	= 4,546 liter
	1 US gallon		= 3,785 liter
	1 imperial gallon	= 1,205 US galls.

	WEIGHT

	1 ounce			= 28,35 gramm
	1 pound (lbs)		= 0,454 kg
	1 hundredweight (cwt)	= 50,802 kg
	1 metric tonne		= 1000 kg
	1 ton			= 1016 kg
	1 ton			= 1,016 metric tonnes

	SPEED
	
	1 foot per second	= 0,305 m/s
	1 mile per hour		= 0,447 m/s
	1 mile per hour		= 1,609 km/h
	1 knot			= 1,151 miles per hour
	1 knot			= 1,853 km/h
	  [ 1 nautical mile per hour ]

	POWER
	
	1 horsepower (hp/HP)	= 550 ft lbf/s
	1 horsepower (hp/HP)	= 1,0139 metric hp
	1 horsepower (hp/HP)	= 76,04 kgf m/s
	1 horsepower (hp/HP)	= 745,7 W
	1 metric hp (mHP/CV/PS/PK) = 75 kgf m/s
	1 metric hp (mHP/CV/PS/PK) = 735,5 W
	1 ft lbf/s		= 0,1383 kgf m/s
	1 ft lbf/s		= 1,356 W
	1 watt (W)		= 0,7376 ft lbf/s
	1 watt			= 0,102 kgf m/s
	1 watt			= 1 J/s
	1 watt			= 1 Nm/s
	1 watt			= 0,00095 B.Th.U/s
	1 kW			= 1,341 hp (HP)
	1 kW			= 1,36 metric (mHP)
	
	FORCE
	
	1 lbf			= 4,448 N
	1 tonf			= 9,964 kN
	1 kgf			= 9,807	N
	1 N			= 0,2248 lbf

	TORQUE

	1 pound-force foot (lbf ft) = 0,1383 kgf m (m-kg)
	1 pound-force foot (lbf ft) = 1,356 Nm
	1 kgf m (m-kg)		= 7,233 lbf ft
	1 kgf m (m-kg)		= 9,8067 Nm
	1 Nm			= 0,102 kgf m
	1 Nm			= 0,7376 lbf ft

	PRESSURE

	1 bar			= 1000 millibar
	1 bar			= 0,98692 atmosphere
	1 millibar		= 0,01450377 pound per square inch

	DENSITY

	Freshwater		= 1,0 t/m3
	Saltwater		= 1,025 t/m3
	Steel			= 7,86 t/m3
	Aluminium		= 2,74 t/m3
	Acryl			= 1,19 t/m3

	Some Examples : 

	A dive deep of : 1200 ft = 1200 x 0,305 m = 366 meter

	A tank of 20 cubic foot = 20 x 0,028 m3 = 0,56 m3 or 560 liter

	A pressure bottle with 4,5 liter under 225 bar 
	has a capazity of 4,5 l x 225 bar = 1012,5 liter 
	with 1012,5 / 28 = 36,16 cubic foot

	Simple formulas : 

	Volume of a cylinder :  (given = diameter and length)

	diameter x diameter x length x 0,785375 = Volume

	example : diameter = 2,5 m , length = 10 m 

	2,5 x 2,5 x 10 x 0,785375 = 49,08 m3

	displacement in freshwater = 49,08 x 1,0 = 49,08 t
	displacement in saltwater  = 49,08 x 1,025 = 50,307 t

	thickness of the cylinder shell given with 1 inch = 25,4 mm

	medium diameter = 2500 mm (2,5m) - 25,4 mm = 2474,6 mm

	periphery = 2474,6 x pi (3,1415) = 7774,19 mm or 7,77 m 

	Area of shell 	= periphery of medium diameter x length
		= 7,77 m x 10 m = 77,7 m2

	Volume of shell material = 77,7 m2 x thickness
			 = 77,7 m2 x 0,0254 m = 1,97358 m3 material

		in steel = 1,97358 x 7,86 (density of steel) = 15,51 t

		in aluminium = 1,974 x 2,74 = 5,41 t


	without any guarante

        ( Carsten Standfuss 05 Dec 2000 )

	NOTE: The numerical notation within and without the United
	      States is not the same. Pay attention to the context
	      to advoid confusion. For example:

		United States		Germany
		-------------		-------
		15,231.234	=	15.213,234

	( Ray Keefer 08 Dec 2000 )

	Question:

	What are PSUBS made of?

	Answer:

	Depends on the design criteria. Ambient designs 
	can be made of fiberglass, steel, even painted 
	plywood. 1 atmosphere designs can be made of
	steel, plexiglass, alumimum, titanium....

	( Ray Keefer 21 Sep 2001 )

	Question:

	What are the controls like?

	Answer:

	On smaller subs they can be aircraft like with a 
	joy stick for the control surfaces. Linkage to the 
	control surfaces can be cables and pulleys with 
	sealed shafts going through the hull. On larger subs they
	can be hydraulic or electric with controls being
	with computer type joysticks or switches.

	Motor controls can be by switches or joysticks.

	The valves for flooding and blowing ballast 
	tanks are from manually operated valves to 
	being remotely controlled hydraulically activated.

	Depends on what the designer wants. Typically
	for a small PSBUS the controls are simple.
	On largers subs the controls are more complex
	because the operator just can't physically
	manipulate the control surfaces himself so
	he needs haudralic assistance, or the valves
	are not conviently location.

	( Ray Keefer 21 Sep 2001 )

	Question:

	What do you need to start building your P-sub?

	Answer:

	Desire, attitude, willingness to learn, money. 
	In that order.

	( Ray Keefer 21 Oct 2001 )

	Question:

	Where can I buy Kittredge K-250 or K-350 plans?

	Answer:

        For a single sheet of the hull of a K-250:

                http://www.psubs.org/store/

                $30 each sheet

        For Full K-250 and K-350 Plans:

                K-250: $250 each set
                K-350: $350 each set
       
                John Maynard
                LAKE DIVER Inc.
                FABRICATOR OF PERSONAL SUBMERSIBLES
                2647 South Broadway
                Wellsburg, New York  14894

                Phone   (607)742-8313
                Email   mongo14904@yahoo.com
                Web     http://johnmaynard.tripod.com/

	( Ray Keefer 29 Apr 2005 )