how come they don't make all sea vessels boat/submarine

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feralkid

Lifer
Jan 28, 2002
16,543
4,630
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How is the captain and crew going to desert the sinking vessel if it's underwater?


The old Momsen Lung, of course.

Momsen_lung.jpg
 

brainhulk

Diamond Member
Sep 14, 2007
9,418
454
126
I meant like a submarine inside a boat. Kind of like a boat/submarine turducken

TurduckenRolls.jpg


So an outside hit would only damage the turkey meat but not the duck meat
 

SOFTengCOMPelec

Platinum Member
May 9, 2013
2,417
75
91
I meant like a submarine inside a boat. Kind of like a boat/submarine turducken

TurduckenRolls.jpg


So an outside hit would only damage the turkey meat but not the duck meat

Ok, so there is a crash, and the ship (with Submarine permanently welded inside), sinks to the bottom.
Now what do the passengers do, 1000 feet (or whatever the depth was) below the sea surface.
Wait for the air to run out ?
They (the built in sub) can't move as the sub is trapped in the damaged/sunk ship.
 

SOFTengCOMPelec

Platinum Member
May 9, 2013
2,417
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It only applies (non-applicable exception, quoted below) if it is 100% air tight (between the bottom and the rest of the ship), I believe.
So after a major collision/damage, the ship can easily sink and/or topple over, as there would be no guarantee that it is air tight.

The quote below from the wiki article would probably NOT apply, as the damage/hole would be below the water line, and NOT extend to above the water surface.

Water will not enter the hull and sink the ship provided the sides of the moon pool extend up inside the hull well above the waterline
 
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dank69

Lifer
Oct 6, 2009
35,485
29,027
136
Ok, so there is a crash, and the ship (with Submarine permanently welded inside), sinks to the bottom.
Now what do the passengers do, 1000 feet (or whatever the depth was) below the sea surface.
Wait for the air to run out ?
They (the built in sub) can't move as the sub is trapped in the damaged/sunk ship.
Well the sub will have to shoot out once the boat sustains catastrophic damage.
 

SOFTengCOMPelec

Platinum Member
May 9, 2013
2,417
75
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Well the sub will have to shoot out once the boat sustains catastrophic damage.

What if that underwater submarine ejecting (seat) mechanism breaks during the collision/explosion/whatever, and how exactly would it work ?

Let's say the sub weighs 5,000 tonnes.
It would be like launching 5,000 torpedoes simultaneously, after a major catastrophe, 100% reliably.
 

dank69

Lifer
Oct 6, 2009
35,485
29,027
136
What if that underwater submarine ejecting (seat) mechanism breaks during the collision/explosion/whatever, and how exactly would it work ?

Let's say the sub weighs 5,000 tonnes.
It would be like launching 5,000 torpedoes simultaneously, after a major catastrophe, 100% reliably.
Right, so pretty easy to do. Have your first mock up on my desk by tomorrow morning.
 

SOFTengCOMPelec

Platinum Member
May 9, 2013
2,417
75
91
Right, so pretty easy to do. Have your first mock up on my desk by tomorrow morning.

Ok.
Titanic emergency Torpedo Submarine Rescue System, will be ready Friday, first thing (N.B. It might be significant that I have not said which Friday).
 

brainhulk

Diamond Member
Sep 14, 2007
9,418
454
126
Ok, so there is a crash, and the ship (with Submarine permanently welded inside), sinks to the bottom.
Now what do the passengers do, 1000 feet (or whatever the depth was) below the sea surface.
Wait for the air to run out ?
They (the built in sub) can't move as the sub is trapped in the damaged/sunk ship.

They would have to push an emergency button that would release giant air bags to prevent the ship from sinking too far

emergency-button.jpg
 

CZroe

Lifer
Jun 24, 2001
24,195
856
126
Water resistance is much greater than wind resistance. Surface buoyancy is also free while freely changing depths costs energy.

They would have to push an emergency button that would release giant air bags to prevent the ship from sinking too far

emergency-button.jpg

DOH! Why don't surface ships have these then?!
 

SOFTengCOMPelec

Platinum Member
May 9, 2013
2,417
75
91
They would have to push an emergency button that would release giant air bags to prevent the ship from sinking too far

emergency-button.jpg

I think they sometimes use a similar technique, to raise up (already) accidentally sunk ships.
E.g. To recover/repair/re-float the ship and/or very valuable cargo (e.g. Gold) and/or historically significant and/or to find out why it sunk/blew-up/collided/whatever.

I have seen TV program(s) about this, and such undertakings are MAJOR nightmares, involving huge amounts of time (days or even weeks), equipment and lots of man power, and maybe many nearby surface/recovery ships.

The thing is that a ship (relatively speaking) can't really carry much weight. Otherwise it quickly goes too low in the water, takes on water and sinks.

So if the gaping holes (due to the collision/explosion/accident/etc) have filled many compartments, the extreme weight of such a vast amount of water, will force the ship to the bottom of the ocean, even with some extra emergency inflatable air-bags (I believe, but I am NOT an expert on ships).

If the air-bag solution worked, then the built in submarine would NOT be needed.
Conversely if the air-bags were not enough to hold the ship afloat, then the submarine may NOT help, as the ship may go well below the crush depth of the submarine (if the sea is deep enough).

There would be a huge number of very serious technical problems, such as the passengers being horribly cramped inside the small submarine (relative to the ship), and it would be difficult to connect services between the ship and the submarine (such as electricity, food supplies, air, communications between ship and submarine, fire escape provisions, toilet/sink waste removal, trash removal, etc).

If this was even slightly a good idea, surely it would have been tried by now ?

The many isolated water tight compartments of the Titanic and its extensive rows of life-boats dramatically failed a long time ago.

Are you sure something similar would not happen again, if they used your submarine/air-float-bag solution ?


_42480602_napoli_refloat_inf416.gif



article-0-14B92C45000005DC-777_634x419.jpg
 
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roguerower

Diamond Member
Nov 18, 2004
4,564
0
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Submarines cost way more than boats. If you did a submarine boat it would be expensive.

For comparison, our latest nuclear subs cost around 8.2 billion, but to build a Nimitz class aircraft carrier which is several times its size, will only cost 4.5 billion.

Your figures are a wee bit off there big guy.

A new Virginia-class submarine costs $2.7bil per unit for FY2014. A new Gerald Ford-class aircraft carrier costs $11.3bil per unit for FY2014.

Now, while by no means are submarines cheap, aircraft carriers are vastly more expensive to construction AND operate.