Why no periscope below 50 ft?

[Capt Jack Harkness]

I realize you won't see much with the scope head below the surface but there's no reason it would break from being too deep. In fact, more than one American sub actually got close enough to photograph submerged Soviet subs with the periscope.

[ETR3(SS)]

It is routine to have the periscope raised before ascending to PD to look for hulls in the water that may not have show up on sonar, like sailboats. So I second this.

[ollie1983]

Surely they would raise the scope prior to reaching the right depth to ensure that they exposed only the minimum of mast?

At what depth can the scope be used safely? I assumed the thing was proofed for the same submerged depth as the sub itself, or it is held inside a part of the sail which is pressure proofed externally?

Or for that matter what about the crew compartment on top of the sail you see them stood when surfaced? Does this close up or is it too sealed by doors etc?

[Julhelm]

It's for technical reasons.

[Capt Jack Harkness]

Fair enough. Something that applies to all masts, I assume?

[tn_prvteye]

Does the technical reason also cause the odd transition to above water/under water view? The engine can't display both at the same time, maybe? Not complaining...the techie in me is just curious.

[jmr]

Bummer to hear it can't be done because of technical reasons but I always liked looking through the scope in the Silent Hunter series and Dangerous Waters when about to surface and submerging.

[Julhelm]

Originally Posted by tn_prvteye

Does the technical reason also cause the odd transition to above water/under water view? The engine can't display both at the same time, maybe? Not complaining...the techie in me is just curious.

That is correct.

[ETR3(SS)]

Originally Posted by ollie1983

Surely they would raise the scope prior to reaching the right depth to ensure that they exposed only the minimum of mast?

At what depth can the scope be used safely? I assumed the thing was proofed for the same submerged depth as the sub itself, or it is held inside a part of the sail which is pressure proofed externally?

Or for that matter what about the crew compartment on top of the sail you see them stood when surfaced? Does this close up or is it too sealed by doors etc?

Typical procedure for ascending to periscope depth involves coming shallow, yet deep enough that you can't get hit by a fully laden supertanker. Raise the scope and then go on up to PD, the scope operator (most likely the OOD) will be scanning the sea surface on the ascent for anything that may be a collision threat that sonar couldn't pick up. Should he see something he can have the ships control party react to avoid a collision, usually an emergency deep. The periscope can be raised at any depth as it penetrates the pressure hull and can withstand the same pressure as the hull. Would be kind of silly to have a test depth that was greater than what your scope could withstand.

The bridge and lookout stations in the sail do have hatches, but that's for streamlining. The sail itself is a free flood area and so is exposed to sea pressure constantly.

[caine007]

What about breaking it at speed?

I can see the radar mast bending pretty easily, the scope looks fairly solid.

[ETR3(SS)]

Originally Posted by caine007

What about breaking it at speed?

I can see the radar mast bending pretty easily, the scope looks fairly solid.

Haven't tested this myself, but there is a speed limit for the masts with and without the fairings raised. Also, Julhelm if you're still lurking this thread: the radar masts are very high. Any particular reason for this? Your resources are what I would consider excellent so puzzled at this.

[Julhelm]

I assumed they would raise to the same height as the periscopes. Also the 50ft depth is hardcoded which gave me problems with certain boats like the Permit.

[ETR3(SS)]

Typically radar on submarines is/was used for contact management during inbound/outbound transit. Therefore raised height wasn't very high as it didn't need to be. I understand your constraints regarding periscope depth though, particularly with the Permit as she had a much smaller sail.

[Shadriss]

I'm gonna second ETR3's descriptions - he's about as accurate as he's allowed to be, assuming his name is his actual Rate (STS1/SS myself, for the record). My guess is that they aren't using "keel depth" for their references, since when surfaced the depths are showing single digits. Makes me think they might be using center-line depth, which is just flat silly.

What strikes me as really odd is that the depths involved in PD aren't exactly hard to come by - just watch a few older submarine specials and they show the whole process.

[Capt Jack Harkness]

Huh, I just assumed it was depth below keel...