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Utrinque Paratus
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Discussion Starter · #1 ·
OK watching a few old war films whilst i get rid of this cold i have a few questions that may sound stupid but I'll ask anyway

1, the sub is at 60 meters and a diver goes outside in gear fixes the rope trapped around the props and gets back in the sub after 30 minutes dive does he need to do decompression?

2, if not what happens when the sub surfaces will the diver be bent?

over to you

Graham
 

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Yes, he would need to do deco as the inside of the hull is at 1 bar-ish. If it weren't the sub would be unable to surface without a long deco after days submerged!

Surely> Maybe? Not knowing owt about subs :D
 

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nope dnt think so, otherewise how could they do emergency accents
 

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Utrinque Paratus
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Discussion Starter · #7 ·
nope, im pretty sure they are at amdient surface pressure, hence the sub can dive and surface quickly without worrying about all the navy boys turning into benders!

Chris Middleton
aka studen guy

so the diver would need to do Deco then or risk being part of the big navy bender thing :D

so if he does have to do deco the sub cant wait or surface so where does that take place

Graham
 

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so the diver would need to do Deco then or risk being part of the big navy bender thing :D

so if he does have to do deco the sub cant wait or surface so where does that take place

Graham
He could deco in the escape chamber?
 

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I would guess in an onboard pot or i an air/water lock
 

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Utrinque Paratus
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Discussion Starter · #10 ·
He could deco in the escape chamber?
As i understand it there are two settings on the chamber allowing water in Equalising and forcing the water out Pressurising as far as i know (and we need a submariner here) there is no middle ground ??

Graham
 

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As i understand it there are two settings on the chamber allowing water in Equalising and forcing the water out Pressurising as far as i know (and we need a submariner here) there is no middle ground ??

Graham
I don't know about 2 settings, but I recall from my visit to the SETT that it drains into the sub for escape purposes.

2 settings sounds a bit odd with all those pumps etc. available to them...
 

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u bugger u beat me to it :teeth:
 

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Utrinque Paratus
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Discussion Starter · #13 ·
I don't know about 2 settings, but I recall from my visit to the SETT that it drains into the sub for escape purposes.

2 settings sounds a bit odd with all those pumps etc. available to them...
I'm just going by a crappy war film i havent got a clue ??
 

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OK watching a few old war films whilst i get rid of this cold i have a few questions that may sound stupid but I'll ask anyway

1, the sub is at 60 meters and a diver goes outside in gear fixes the rope trapped around the props and gets back in the sub after 30 minutes dive does he need to do decompression?

2, if not what happens when the sub surfaces will the diver be bent?

over to you

Graham
Submarines are pressurised at surface pressure (well, probably slightly above if truth be known) so the crew don't need to decompress when the submarine surfaces. So if - as in your example - a diver were to exit the submarine, work outside at 60m for 30mins and then return to the sub, he would indeed need to decompress before entering the main body of the submarine or he'd get bent. Whilst it's fairly obvious that the submarine would need some form of 'airlock' to allow a diver to exit and reenter the sub without flooding it, I doubt if the pressure inside this airlock is controllable enough to effectively use the airlock to slowly bring the diver up from depth in a dry environment.
 

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Utrinque Paratus
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Discussion Starter · #15 ·
Submarines are pressurised at surface pressure (well, probably slightly above if truth be known) so the crew don't need to decompress when the submarine surfaces. So if - as in your example - a diver were to exit the submarine, work outside at 60m for 30mins and then return to the sub, he would indeed need to decompress before entering the main body of the submarine or he'd get bent...
OK but how does he do the decompression ??

Graham
 

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OK but how does he do the decompression ??

Graham
Pass! I'd be surprised if the submarine has a pot onboard - seems far too bloody dangerous! But then I see no other way of decompressing a diver onboard a submarine... it's an interesting question, Graham!

[UPDATE]

Found this page earlier...

U.S. Submarines

Now what's interesting is this bit...

"Diver Lock-out Chamber
A spherical diver lock-out chamber, 2.4 meters (8') in diameter is fitted above the shafts and attached to the aftermost section of the pressure hull. The chamber allows a diver to enter or exit the submarine from the area between the shafts at depths of up to 45 meters (150'). The chamber can be fitted with decompression capability if required."

Now that to me reads that the pressure inside the 'air lock' can be controlled by the crew inside the submarine to allow the pressure to be very precisely controlled to allow a dry decompression schedule to be run. My guess is that the submarine you saw in the movie had something similar! Well, we'd hope so for the diver's sake, eh! ;)
 

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2, if not what happens when the sub surfaces will the diver be bent?
I would imagine the diver would be bent long before the sub surfaced if he did not decompress before entering the main part of the sub.

I have forwarded these questions to an ex Navy diver I know. Hopefully he will be able to shed some light on this.

Cheers/Nic
 

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The sub would be at 1 bar inside at any depth!
The diver would deco in the hatch or he would be bent after the 60m dive for 30mins!

Well thats what I think

Ive never heard of a sub doing deco!

Just how deep is the deepest they would send a diver out of a sub to do anything like this and then the have the diver going back into the sub ???
 

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Utrinque Paratus
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Discussion Starter · #19 ·
I would imagine the diver would be bent long before the sub surfaced if he did not decompress before entering the main part of the sub.

I have forwarded these questions to an ex Navy diver I know. Hopefully he will be able to shed some light on this.

Cheers/Nic
could you also sak what would be the deepest depth that they would send a diver outside ?

good question ada
 

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could you also sak what would be the deepest depth that they would send a diver outside ?

good question ada
I suppose it depends on what (breathing) gas they have onboard. I know they dive higher ppO2 due to military risk but there has to be a finite limit. It would be interesting to see what the answer is; I will see what I can dig out.
 
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