Re: [PSUBS-MAILIST] Euronauts Ballast and Trim System.

[MerlinSub@t-online.de (Carsten Standfuss)]

Hi Dan - good feeling - isnt it ? :-))

Hi Charles - is between the lines. 

regards Carsten

Charles Perkins schrieb:
> 
> Thanks Carsten for your excellent and informative reply.
> 
> I have lately been wondering how to choose appropriate volumes for the
> hard and soft tanks. Your example gives me a useful baseline to work
> from.
> 
> If you have a surface displacement of 57,5 ts and a submerged
> displacement of 67,2 ts then your 'air displacement', or the volume
> that is above the surface, is 9,7 ts... (ignoring, of course,
> free-flooding areas, but including anything of water-displacing volume
> which is temporarily above the surface.) This explains why submarines
> have small 'sails' and low freeboard.
> 
> Please correct me if I am wrong!

Thats right. 
 
> When you put the Euronaut in the water, how much freeboard do you
> expect to have? How much freeboard you think is necessary to be safe in
> the open sea? What sea conditions do you expect to be able to operate
> on the surface in? If it gets worse than that, you can just dive, of
> course...

Two kinds of freeboard: 
For saftey and class requirements - the lowesr point with the boat in
surface condition - means hatch open - is the hatch. This freeboard can
be easy increased by increassing the hatch cylinder. 
The other freeborad is the freeboard of the deck / hull - this freeboard
gives you the seaworthness. 

Sample : 

Boat type 1
Hatch opening 1 m over the waterline and deck 1 meter over the
waterline.  Tanks 10 ts 

Boat type 2
Hatch opening 2 m over the waterline and deck 0,5 meter over the
waterline.  Tanks 5 ts 

Boat 2 is more safe in fact of flooding via the hatch - but boat 2
is the better seaship. 
 
If the boat is really small like a K-Psub - i prefer solution type 2. If
the boat is large than more in direction type 1

The freeboard of euronaut are : 

superstructure deck   	= 800 mm
pressure hatch 		= 1400 mm
sail top hatch 		= 2100 mm 

Boat can stay at any seastage - but crew maybe not. So if it get to
heavy we will resting on the ground - If we have a good waterdeep ! 

> Do most submarines reserve 15% of their volume for hard and soft tanks?

Between 10-30 % - large Russian more to 30% - large US more to 10 % 
The 23 meter long XXIII of WWII has only 10% and that was clear to small
- but the Euronaut size Seahorse of Bruker Physik has only 6 % ! But
Bruker never called them "seagoing" but called the "For protected costal
waters.."

I blow both tanks out hard and soft to get an maximum seaworthness
because my hard tanks are relative big. 

Make a matrix : put all boats of the size you wish in. 
Wrote displacement and softtanks size in - than look for the reports of
the boat.. good diver , bad diver , all time under the wave at seastage
more than 4.. gives you a feeling. For a first calculation 15-20 % is
okay. 

Both Euronaut and Sgt.Peppers has about 18 %. 
Euronaut for seaworthness, and Sgt.Peppers so a man can stay on the deck
upright without capzied the boat over the side or the bow or the stern ! 

>   I guess that the larger the submarine is, the smaller the percentage
> can be to achieve the same freeboard. Very small psubs must have
> proportionately larger MBT.

Thats right. One trick is to increase the free flooding superstructure
of the deck and build a bouancy tank into the deck at the bow. Many
boats of WWII use this trick. 

Euronauts surface speed is limited by her owen bow-wave at about 8-9
knots.  At this speed the bow wave climed over the deck and the boat
start to dive dynamicly into her own bowwave ! 
So surface speed is also a question of tank size and freebord - special
for this teardrop kind boat hulls . 

> On the other hand, I would expect the size of the VBT in proportion to
> the rest of the boat to remain the same or actually get larger as the
> size of the vessel gets bigger because there is more mass to trim. I
> imagine a boat that will have a greater dynamic range of cargo (more
> people and equipment one day, less the next) will also have to have
> correspondingly larger VBT.

Yes thats more or less right - but normally the don't increase the tanks
size.. the just added more tanks. 

VBT on K-psub - one in the center of the pressure hull. 
VBT on Euronaut size boat - one at the bow and one at the stern
VBT on bigger boats :one stern, one middle  -one aft .. etc.ect.. 
 
> I think it is quite clever how you can use the Diver Lock Out chamber
> to blow the ballast tanks. That shows some good integration, and as an
> electrical engineer friend of mine often says... 'joined-up-thinking!'

I allways looking for double-function - and for saftey issues. 
 
> Do you have sensors in the ballast tanks to indicate how much water you
> have in the tanks?

In the hard yes - in the soft not - the soft are allways dived with open
top valves - the bottom has an open hole - so they are full all the
time. On the surface somebody is looking from the sail - and if bubbles
of air comes out at the stern and the bow the tanks are empty. 

After some time at havy sea we have to reblow the tanks because of some
flooding by the affect of the sea and dynamic impacts.  

> In one of the photos you have placed on the Moki picture exchange, I
> saw what looked like a computer screen with a boat diagram and tank
> capacities. Is this system for diagnostics and status only, or can the
> computer control some functions?

There will be 3 Computers for diagnostics and status only. The controlls
are hardwired. I never will accept that mr.Gates control any part of my
boat.. ;-)
But the computer on top of the hardwire will be use for all kind of
diagnostic. Including seamaps, decompression diver calculation,
calculation of range, fuel consumption, video of the cameras and the
Rov. And much more. All 3 computers have the same software - so I can
lost 2 of them. 
 
> (As a computer guy, I can really appreciate a good old-fashioned manual
> system, where a computer bug is less likely to crash your boat.)
> 
> I am impressed with the amount of thought you have put into making the
> Euronaut a safe vessel to travel in.
> 
> I don't mean to annoy or distract you with too many questions... I
> think we'd all prefer you spent your time getting the boat completed
> and launched!
> 
> Thanks,
> Chuck
> 
> On Jun 7, 2004, at 2:37 PM, Carsten Standfuss wrote:
> 
> > Hi Charles -
> >
> > Bigger tanks partlly filled with water, soft or hard, ambient or not,
> > pressure compansate ambient or not.. will not work on a submarine..
> >
> > The reason is what we call the "free surface". In simple words:
> > If the boat move under an angle for example to the bow - the water
> > in the tanks follow this angle the and the longitudinal trim and
> > stability get very quick out of control. Even a big Car-ferry can quick
> > capzied if the fire-sprinkler system flooded the car deck with some
> > inch
> > of water.(but in this case to the side).
> >
> > For this reason submarine have two types of tanks :
> > Big Softanks for the freeboard on the surface - allways
> > completly filled underwater !
> > Small hard tanks partlly filled for the zero bouancy.
> > If the hard tanks located near bow and stern we called them trim tanks.
> >
> > Euronaut has a surface displacemnet of 57,5 ts.
> > One Soft tank in the bow and one in the stern.
> > Each soft tank has = 4,5 ts = 9 ts together.
> > One hard tank in the bow and one in the stern.
> > Each hard tank has 0,7 ts = 1,4 ts
> >
> > The boat dives with the soft tank completly filled and the hardtanks
> > to 50% = So dive displacement  in this theoretical disscussion is
> > 57,5 + 9 + 0,7 = 67,2 ts.
> >
> > Note : The hard tanks in Euronaut are inside the soft tanks.
> >
> > Diving : Open the vales on top of the soft tanks.
> > This tanks are open at the bottom - the air escapes -water floods the
> > tank completly. The hard tanks are still emtpty - than I open the
> > bottom
> > vale of the hard tank - water gets in a litle - but than stops because
> > of the sliglty compressed airbubble inside this tanks. Than open the
> > top-vale of this tanks until the water level is in a amount I want -
> > near 50% depents on the boats load and water density - close than top-
> > and bottom vales of this tanks.
> >
> > Surfacing : Close the top-vales of the soft tanks - open the top vale
> > of
> > the hardtank and let compressed air into this tanks until the
> > airpressure inside is higher than the outside waterpressure. Than open
> > the bottom valve of the hardtanks and the water gets out - until all
> > water is out - than the air gets out of this bottom valve - and will be
> > catch by the softtank (..the hard tank is inside this tank..) The boat
> > surface and it depents of the deep it was and the pressure and amount
> > of
> > air I blow to the hard tank if the soft tanks are completly empty or
> > not. If not I blow more air to the hardtank with open bottom vale until
> > the boat is completly in surface trim. Than I close the top- and the
> > bottom  vale of the hard tank. Go on deck with two metal blindflanges
> > with treads and close the softtank-topvales with this additional saftey
> > feature tight. It doesnt matter if now somebody plays with the controls
> > - the Euronaut is now  a surface boat until somebody remove this plate.
> > Another function of this blindflanges is that we can test the functon
> > of
> > the outside and remote controlled softtank-topvales without to flood
> > the
> > tank.
> >
> > The reason for the size of the softtank is the amount of freeboard and
> > seaworthness I want. The reason for the sizes of the hard tanks is
> > given
> > by the differnet density of the saltwater of the north sea (1,025) and
> > the baltic sea (1,0= freshwater) and the need to compensate the
> > diffence
> > in the load of the boat mostly if the diesel tanks are up to 90% filled
> > or down to 10% empty.
> >
> > The diesel tanks are inside the pressure hull - one forward and one aft
> > - so I can trim the longitudinal trim with this tanks also.
> >
> > The freshwater (drinkwater) tank for the toilet, pantry and shower has
> > the same size than the wastewater tank - and is locate close together.
> > If the freshwatertank is filled - the wastewater tank is empty - and
> > opposite.
> >
> > I have two ways to blow the tanks with compessed air - one is inside
> > the
> > pressure hull - and the other one is outside. I have two compressors -
> > and two highpressure pipes systems. In emergency I can also blow the
> > tanks with the helium normaly use for the diver chamber.
> >
> > The air storage capacity is 30 units x each 50 Liters x 220 bars =
> > 330000 liters so I can blow the soft and hardtanks = 9000 + 1400= 10400
> > liters ->  330000/10400 = 32 times ! The is no real reason to blow the
> > tanks so many times but most of the storage bottles are used to blow
> > the
> > diver lockout lock in chamber. To blow the soft and hardtanks I need
> > about one bottle each dive.
> >
> > But the diver chamber has 7000 liters volume in a deep of 150 meter
> > this requires : 7000 x 15 bar = 105000 liters of gas before the chamber
> > is equal to the seapressure and the bottom hatch can be open. I double
> > the storage capacity for saftey reasons.
> >
> > There is another pipe so I can blow with the gas inside the
> > diverchamber
> > also direct the soft- and hardtanks. To do this the boat has to to
> > surfac dynamicly a little so that the pressure in the diverchamber is
> > higher than the seapressure - then the decompression vale of the
> > chamber
> > will be wired to the softtanks - and the gas can be use for twice
> > functions.
> >
> > There are two high pressure seawater pumps in the boat - but this are
> > emergency pumps to drain the bilge.
> > They are not connected to the Ballast- and trim system.
> >
> > I have 3 additional drop weights - each 1 ts heavy which can be release
> > mechanical by turn a key 60 degrees. The reason is that this is the
> > fastest way to create lift in case of a leak.
> >
> > There are no seawater pipes or any outside pressure pipes inside the
> > sub. In fact that all dive valves are remote controlled there are no
> > outside pressure pipes anywere in the boat ! Only small high pressure
> > air pipes. If this pipes breaks inside and outside the sub (!) than
> > only
> > a very little amount of water can get inside the sub.
> >
> > Hope this help..  a scetch of the tanksystem is ate WWW.Euronaut.org at
> > the page "Technische Daten"
> >
> > regards Carsten
> >
> > Charles Perkins schrieb:
> >>
> >> Carsten,
> >>
> >> Do you mind telling us a little about the ballast system on the
> >> Euronaut?
> >>
> >> I am wondering:
> >>
> >> How big are your VBT (Variable Buoyancy Tanks) compared to the overall
> >> volume of the Euronaut (minus the Main Ballast Tanks, which I assume
> >> you will flood when you dive?)
> >>
> >> How big are the MBT compared to the rest of the boat?
> >>
> >> How do you intend to "blow" the MBT when you surface... will you use
> >> high pressure air, pumps, or both?
> >>
> >> How much air for ballast purposes do you have stored in the cylinders
> >> in (or on) the boat? How many cylinders (of what size) does that take?
> >>
> >> I ask about the Euronaut because that is the size of submarine that
> >> particularly interests me.  I do my day-dreaming about submarines
> >> ranging from the size of Peter Madsen's Kraka (what a cool looking
> >> boat!) to something the size of your vessel... I like the idea of
> >> being
> >> able to cruise for a couple of days surfaced or submerged before
> >> returning to port.
> >>
> >> I would like to know more about Peter's new UC 3 project... It is too
> >> bad I can't read Danish.
> >>
> >> Thanks all you Psubbers for putting together an excellent community.
> >> I've been lurking for a while now. (Isn't that what submariners are
> >> best at?)
> >>
> >> With enthusiasm,
> >>
> >> Chuck
> >>
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