Re: [PSUBS-MAILIST] Reserved buoyancy

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

Yes was a typo.. should be read ..kg -sorry. Carsten

Erik Muller schrieb:
> 
> Grrrr..
> Marius,
> I KNOW the principals involved!, I am a physicist!
> Displacement is totally decoupled from the TYPE of the fluid, it is the
> boyant force which is different and which is dependant on the density!
> There just seemed to be a typo in Carsens original post where there was
> a  'm^3' where I would have expected  'kg'!
> humph. I might seem like it sometimes.. but I like to think I am not
> excessively thick ALL the time...!
> sigh.
> 
> But thanks for that fun experiment, I will show my neice.
> EM.
> 
> Greeff, Marius (M) wrote:
> 
> >I posted a photo of this on moki.
> >
> >Regards,
> >Marius
> >
> >-----Original Message-----
> >From: Greeff, Marius (M)
> >Sent: 11 March 2004 07:39
> >To: personal_submersibles@psubs.org
> >Subject: RE: [PSUBS-MAILIST] Reserved buoyancy
> >
> >Thanks Carsten,
> >The mid section where my conning tower is located is 21mm thick steel,
> >grade of steel I am not sure of so drop testing will be no1 on list of
> >tests. This already with the first section of coning tower displaces
> >close to 1 m3 and weighs 660Kg. This section is 1.35m long. Adding the
> >rest of the hull and conning tower will take it to 1.85 m3. Here I will
> >use 1/4" thick steel where view ports will be placed. I would like my
> >buoyancy correct on paper to cancel out any other parts still to come
> >like the motors and battery pods. I will ammend my design to a point
> >where it will work before I make another hasty buy.
> >
> >PS. Erik Muller, fun experiment: raw egg floats in salt water and sinks
> >in fresh water.
> >
> >Kind regards,
> >Marius
> >
> >-----Original Message-----
> >From: Carsten Standfuss [mailto:MerlinSub@t-online.de]
> >Sent: 10 March 2004 10:35
> >To: personal_submersibles@psubs.org
> >Subject: Re: [PSUBS-MAILIST] Reserved buoyancy
> >
> >Yes thats right - the body displace stil the same 1cm of something.
> >But the density of something is different - and there with on a planet
> >with constant gravitation - the lift force - bouancy.
> >
> >A sub of a volume of excat 1 m3 and a weight of 1 t or 1000 kg
> >in freshwater with a density of 1,0 will just be in dive trim.
> >It displace excat 1000 kg of water.
> >
> >Saltwater has an higher density = about 1,025 t per m3 (or 1025 kg)
> >So you can build the sub 0,025 t or 25 kg heavier and it will be still
> >dive trim.
> >
> >Put your 1m3 sub in mercury with a density of 13,595 t per m3
> >and you have to add 12,595 t of lead or something into your sub before
> >it dive.
> >
> >If you dive with a 1m3 and 1 t heavy sub in petrol tank to inspect a big
> >oil raffinere from Shell.. it will sunk strait to the bottom of the tank
> >-> Petrol = 0,68 -0,75 t per m3 means negative lift of 0,25-0,32 t
> >
> >Real sample :
> >
> >Euronauts weight is about 57 ts.
> >Baltic sea has about 1,000 t per m3 density.
> >North Sea has about 1,025 t per m3 density.
> >
> >If I leave the baltic on dive station via the Kategatt way -
> >the lift of the water will increase of 1,025 x 57 = to 58.425 t
> >and the boat will be force on the surface with a lift of 1,425 t - the
> >weight of a Kittredge size sub..
> >
> >It is a bad idear to dive with a militar high sea sub from the South
> >Atlantic into the Amazonas river delta in dived condition..
> >A 8000 ts boats "lost" about 195 ts of lift  -> bouancy  ;-)
> >
> >Sorry about my poor english language.. Carsten
> >
> >Erik Muller schrieb:
> >
> >
> >>Hello Carsten,
> >>I am just following up on that calc.
> >>I am unclear why the displacement is different for salt and fresh
> >>
> >>
> >water.
> >
> >
> >>I know that the boyant force will be different, but surely if I put a
> >>1cm cube of metal into a cup of liquid, I still displace 1cm,
> >>
> >>
> >regardless
> >
> >
> >>of anything else disolved., Do you mean to write that the boyant force
> >>is 1 5323 kg (i.e. rather than  m^3) in fresh and 1 5706 kg in sea?
> >>Thanks Carsten,
> >>EM.
> >>
> >>Carsten Standfuss wrote:
> >>
> >>
> >>
> >>>Show us the general weight calculation of your boat here..
> >>>
> >>>I estimate that :
> >>>
> >>>A.1) Estimate bouancy calculation :
> >>>
> >>>0,921 by 0,921 x 3,1415/4 x 2,3 m = 1,5323 m3 displacement in
> >>>
> >>>
> >freshwater
> >
> >
> >>>(1,5706 in seawater) without endcaps and outside displacement parts.
> >>>
> >>>B.1) Estimate weight calculation :
> >>>
> >>>hmm...
> >>>Which tickness has the pipe ?  Mild steel or stainless ?
> >>>
> >>>regards Carsten
> >>>
> >>>
> >>>Steven Mills schrieb:
> >>>
> >>>
> >>>
> >>>
> >>>>Ouch ! Marius,
> >>>>
> >>>>What grade and standard of steel did you get?
> >>>>
> >>>>--Steve
> >>>>
> >>>>On Wed, 10 Mar 2004 15:58:33 +0200 "Greeff, Marius (M)"
> >>>><Marius.Greeff@sasol.com> writes:
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>>Howdy,
> >>>>>I think I bought the wrong piece of steel to start my pressure hull
> >>>>>with. I end up calculating about 700kg buoyancy reserved on the
> >>>>>design before motors, batteries and all the rest are added. I wish
> >>>>>to get this right before I buy the rest of the steel needed to
> >>>>>build. My design have the hull already 2.3m long and a diameter of
> >>>>>921mm(36").
> >>>>>
> >>>>>Kind Regards
> >>>>>Marius
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>>
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