Periscopes and other holes question!

Rhodes · 03-12-18, 07:08 PM

When thinking about submarines, playing the sims and seeing some film about the them, always had a few questions about how some sub systems work.
Using google to search is a normal thing this days, but I lack the correct terms or got the same thing and that is not what I am looking for.

My question about periscopes is not how do they work, but more how they are watertight, specifically the all system and not just the optical part. And one can focus in WW2 subs, since latter ones would use the same principle and earlier ones probably the same.
So, are the periscope wells watertight, and how? Do they have some kind of lid/door (rubber/metal) that opens and closes? If so, those are design to withstand high pressure, correct?
And if one decides to raise the periscope at 100m or 150m, what consequences would that act provoke? (hypotetical question, I do not even if it is possible to do so).
And the voice tubes form the towers to the control room? Logic tells me that they can not be full open, they have valves?
It was always that bothered me in terms of knowledge. Even more in seeing photos of the towers and the periscopes. Some had a metal lid attach to the well, but in a crash dive situation no one would put the lid in place (I think). Other pictures one can see the periscope head, so decided finally to ask here for some knowledge and of course, if there are websites about the subject, I appreciate knowing them also.

ET2SN · 03-12-18, 08:22 PM

Voice tubes were way before my time.

I did end up certified to do Subsafe inspections and maintenance (QAI) on scopes and hull penetrations (wiring and hydraulics), though. This is usually reserved for A Gang and M Div but I did shipyard tours on both ships I served on.

There's not as much keeping the ocean out of the attack center as many people believe. The scope barrel is rated to test depth since it contains the optics and a lot more. Think of the barrel as its own sub.

The only physical connection to the sub are the lift cylinders and the electronics connections.

What keeps the water out is a packing gland mounted to the hull. Very similar to the shaft seals but much simpler in construction. As the outside water pressure gets higher the gland seals tighter to the scope barrel.

So, yes you could raise the scope at 400 feet deep or even at test depth. The action of the gland would make it tougher on the hydraulics to raise the scope but it would work (it also becomes much harder to turn the barrel).
The only reason to raise the scope is if you needed to fix something or, more likely, retrieve whatever was dropped from the scope stand into the scope well.

So, why do all of the games model scope damage if you raise it below X feet? Good question, I have no idea.

In practical terms, being deep AND fast could lead to damage to the barrel and the packing gland, but it would be rare.

Rhodes · 03-13-18, 07:13 AM

I see, thank you!

03-12-18, 07:08 PM	#1
Rhodes Silent Hunter Join Date: Aug 2005 Location: Figueira da Foz, Portugal Posts: 4,486 Downloads: 109 Uploads: 0	Periscopes and other holes question! When thinking about submarines, playing the sims and seeing some film about the them, always had a few questions about how some sub systems work. Using google to search is a normal thing this days, but I lack the correct terms or got the same thing and that is not what I am looking for. My question about periscopes is not how do they work, but more how they are watertight, specifically the all system and not just the optical part. And one can focus in WW2 subs, since latter ones would use the same principle and earlier ones probably the same. So, are the periscope wells watertight, and how? Do they have some kind of lid/door (rubber/metal) that opens and closes? If so, those are design to withstand high pressure, correct? And if one decides to raise the periscope at 100m or 150m, what consequences would that act provoke? (hypotetical question, I do not even if it is possible to do so). And the voice tubes form the towers to the control room? Logic tells me that they can not be full open, they have valves? It was always that bothered me in terms of knowledge. Even more in seeing photos of the towers and the periscopes. Some had a metal lid attach to the well, but in a crash dive situation no one would put the lid in place (I think). Other pictures one can see the periscope head, so decided finally to ask here for some knowledge and of course, if there are websites about the subject, I appreciate knowing them also. __________________ http://www.flickr.com/photos/16416646@N05/

03-13-18, 07:13 AM	#3
Rhodes Silent Hunter Join Date: Aug 2005 Location: Figueira da Foz, Portugal Posts: 4,486 Downloads: 109 Uploads: 0	I see, thank you! __________________ http://www.flickr.com/photos/16416646@N05/

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03-12-18, 08:22 PM	#2
ET2SN ET2/SS Join Date: Oct 2017 Posts: 2,503 Downloads: 58 Uploads: 0	Voice tubes were way before my time. I did end up certified to do Subsafe inspections and maintenance (QAI) on scopes and hull penetrations (wiring and hydraulics), though. This is usually reserved for A Gang and M Div but I did shipyard tours on both ships I served on. There's not as much keeping the ocean out of the attack center as many people believe. The scope barrel is rated to test depth since it contains the optics and a lot more. Think of the barrel as its own sub. The only physical connection to the sub are the lift cylinders and the electronics connections. What keeps the water out is a packing gland mounted to the hull. Very similar to the shaft seals but much simpler in construction. As the outside water pressure gets higher the gland seals tighter to the scope barrel. So, yes you could raise the scope at 400 feet deep or even at test depth. The action of the gland would make it tougher on the hydraulics to raise the scope but it would work (it also becomes much harder to turn the barrel). The only reason to raise the scope is if you needed to fix something or, more likely, retrieve whatever was dropped from the scope stand into the scope well. So, why do all of the games model scope damage if you raise it below X feet? Good question, I have no idea. In practical terms, being deep AND fast could lead to damage to the barrel and the packing gland, but it would be rare.