could US subs dive/surface so fast?

[Laffertytig]

ive noticed that compared with gwx in SH3 i can dive/surface a lot faster in SH4. also were US subs able to surface/dive when not moving like in SH4?

[seaniam81]

The american subs were pretty quick in getting under some reading I've done suggests around 30-50 seconds for a dive. My reading also suggests it took a lot longer to surface, mostly on perpose to stop hull poping. And yes a boat could dive and surface with out forward speed. It took a lot of compressed air and was noisy but it could be done.

[mrbeast]

IIRC crews trained to crash dive in around 30 seconds, at least that was the target it also depended on the type of sub. Something big such as the USS Narwhal took longer and was one of the reasons why large cruiser type subs were abandoned in favour of fleet boat types.

[mookiemookie]

Originally Posted by seaniam81

The american subs were pretty quick in getting under some reading I've done suggests around 30-50 seconds for a dive.

Everything I've read suggests this also.

[Laffertytig]

yeah that would be for a sub runin at flank then doin a crash dive, not for a sub on the surface or at periscope depth at all stop. in SH4 u can go from periscope depth to 90 metres in 2 min then back up in 2 mins, just like an elevator!

the main reason skippers didnt wait to see the torps hiting was so that they had time to go deep. stayin at periscope to should be a risk but not so in SH4. i know in SH3 the major mods all fixed this to more realistic levels so that it took more time to dive and surface but it look like noone has done this sith SH4 yet.

i would do it myself if i knew what files to change, anyone got any ideas?

[Wilcke]

This is an interesting topic, I suppose that since mechanically the sub can come to periscope depth so quickly without the "noise" and alerting the escorts, one could just do it a bit slower and hold at various depths instead of just hitting the old "P" button.

When using the Trigger Maru mod its bit more realistic in that once your torpedoes are on their way its best to just go deep evade and plan a reattack for a couple of hours later from a new position.

Would be cool if one could implement the "hull plate popping" and have the escorts key in on that. There is always something to work on.

[Ducimus]

My reading leaves me to believe that 30-35 seconds was the goal, with 40ish being the average.

[beartooth91]

I haven't brought this up before because 1) there wasn't a topic to do so, and 2) I'm not sure what can be done about it game-wise:

I am an ex-Navy Nuke submariner (USS Pintado SSN-672 '87-90), and US subs - including WW2 fleet boats normally surfaced without air. When submerged, boats are normally trimmed to have a slightly negative buoyancy (so going to all stop to preserve the batteries isn't realistic either). Just prior to surfacing, the order "Prepare to surface without air" is given and the boat is driven to the surface with propulsion. At this point, the main deck is awash and the shortly thereafter, the Low Pressure Blower is started which blows the remaining water out of the ballast tanks. My reading indicates our WW2 fleet boats surfaced the same way - I believe, the LP Blower in those days was called the Turbo Blower. If memory serves, it took Pintado 10-20 minutes to reach a normal surface running trim after the LP Blower was started.
Just my 2 cents here.

beartooth91

[Wilcke]

Originally Posted by beartooth91

I haven't brought this up before because 1) there wasn't a topic to do so, and 2) I'm not sure what can be done about it game-wise:

I am an ex-Navy Nuke submariner (USS Pintado SSN-672 '87-90), and US subs - including WW2 fleet boats normally surfaced without air. When submerged, boats are normally trimmed to have a slightly negative buoyancy (so going to all stop to preserve the batteries isn't realistic either). Just prior to surfacing, the order "Prepare to surface without air" is given and the boat is driven to the surface with propulsion. At this point, the main deck is awash and the shortly thereafter, the Low Pressure Blower is started which blows the remaining water out of the ballast tanks. My reading indicates our WW2 fleet boats surfaced the same way - I believe, the LP Blower in those days was called the Turbo Blower. If memory serves, it took Pintado 10-20 minutes to reach a normal surface running trim after the LP Blower was started.
Just my 2 cents here.

beartooth91

Thanks for the information, I have only been driving these virtual subs for about a year and I always wondered about the Dive/Surface abilities. Now I have a better picture!

Who knows how our sim is coded in replicating this dive/surface activity.

Thanks

[ssbn627g]

Originally Posted by beartooth91

I haven't brought this up before because 1) there wasn't a topic to do so, and 2) I'm not sure what can be done about it game-wise:

I am an ex-Navy Nuke submariner (USS Pintado SSN-672 '87-90), and US subs - including WW2 fleet boats normally surfaced without air. When submerged, boats are normally trimmed to have a slightly negative buoyancy (so going to all stop to preserve the batteries isn't realistic either). Just prior to surfacing, the order "Prepare to surface without air" is given and the boat is driven to the surface with propulsion. At this point, the main deck is awash and the shortly thereafter, the Low Pressure Blower is started which blows the remaining water out of the ballast tanks. My reading indicates our WW2 fleet boats surfaced the same way - I believe, the LP Blower in those days was called the Turbo Blower. If memory serves, it took Pintado 10-20 minutes to reach a normal surface running trim after the LP Blower was started.
Just my 2 cents here.

beartooth91

I don't remember trimming with slight negative bouyancy. What I remember the goal being is a 1/3 trim. Memeory might be a bit off, but it was ahead 1/3, 1 or 2 degree down angle, hands off the planes and helm with no depth drift or course drift.

But the surfacing without air is right.

[Sailor Steve]

On the other hand:
"The main ballast tanks are partially blown to surface normally."
http://www.maritime.org/fleetsub/chap18.htm#18C

As to trim, WW2 fleet boat doctrine says this:
"Submerged operations are usually carried on with the submarine in the state of neutral buoyancy."
http://www.maritime.org/fleetsub/chap18.htm#18B

Of course perfect neutral bouyancy was impossible to maintain without use of the dive planes and/or pumps, so "hovering" was indeed impossible, and depth-maintenance difficult while silent running.

[Laffertytig]

so the GWX and NYGM mods pretty much have things spot on then in SH3. if it was possible to fix in SH3 then it must be possible in SH4 as well, it just a matter of time i guess

[beartooth91]

Originally Posted by Sailor Steve

On the other hand:
"The main ballast tanks are partially blown to surface normally."
http://www.maritime.org/fleetsub/chap18.htm#18C

As to trim, WW2 fleet boat doctrine says this:
"Submerged operations are usually carried on with the submarine in the state of neutral buoyancy."
http://www.maritime.org/fleetsub/chap18.htm#18B

Of course perfect neutral bouyancy was impossible to maintain without use of the dive planes and/or pumps, so "hovering" was indeed impossible, and depth-maintenance difficult while silent running.

"At the sounding of the signal, three blasts of the diving alarm, or the passing of the word "Surface, Surface, Surface," the various actions necessary are performed.
The bow planes are placed on ten degrees dive and rigged in automatically unless the conning officer gives other instructions. A report, "Bow planes rigged in," is made to the conning officer. Speed is increased to about 6 knots to give maximum lift. Due to the up-angle on the ship, the increased speed makes the inclined surface of the hull effective and the resultant lift raises the ship. The stern planes are used to limit the up-angle to about 5 degrees. The up-angle may be increased by blowing the bow buoyancy tank. Blowing the safety tank increases the positive buoyancy. However, this is not usually done.
The main ballast tanks are partially blown to surface normally. After surfacing, the high-pressure air is secured and the blow is completed with the low-pressure blowers."



And with regard to the 2nd link and quote: I believe that's a very general description. Perhaps its different for WWII fleet boats, but, on my boat it was pretty much common knowledge that all stop for long periods you would very slowly sink.

[beartooth91]

As to trim, WW2 fleet boat doctrine says this:
"Submerged operations are usually carried on with the submarine in the state of neutral buoyancy."
http://www.maritime.org/fleetsub/chap18.htm#18B


Read the above link, but several sentences down:

"The state of exact neutral buoyancy is probably never attained, but the approximation is near enough to allow depth control to be exercised easily by the diving officer. In all normal submerged operations, the submarine is underway at relatively slow speeds. This horizontal motion through the water enables the surfaces of the diving planes to correct the effect of any slight positive or negative buoyancy and also to increase or decrease the submerged depth at the order from the conning officer."

Now, at least in my cold war days, a slight negative buoyancy was preferred I suppose, because at periscope depth, you'd rather sink vs broach and flap your fairwater planes at the Soviets - in the event of a loss of trim control.

[Laffertytig]

yeah i just tested this again with the new GWX mod for SH3. it takes around 9 mins to get down to 90 metres at all stop and u actually sink if u stay at 0 knots

spot on