Heavy seas and rolling motion

mike_espo · 05-14-09, 04:31 PM

I noticed in SH 3 how a u boat would toss and roll in heavy seas while submerged, even at depths of 200+ ft or so. However, in SH 4, a gale can be raging overhead and the boat is rock steady at periscope depth or about 50 feet or so.

It seems that SH3 was more realistic in this regard.

Is there a way to edit this somehow?

thanks

rditto48801 · 05-14-09, 09:27 PM

Waves are on the surface, a dived sub is 'below' the waves.
Why would a sub 'under' the waves be affected by them?

After doing a little googling, I found an FAQ page (apparently from the Royal Navy, relating to nuclear subs), but it seems to fit the subject at hand.
http://www.royalnavy.mod.uk/operatio...tFormat/print/
(near the bottom)

Quote:

Q. Can you feel the waves on a submarine?
It depends on the size of the waves on the surface. During normal weather conditions, a submerged submarine will not rock with the motion of the sea. In fact, during moderate storms the submarine remains level at its submerged depth while the waves crash above. In extremely violent storms, like hurricanes or cyclones, wave motion can reach to a depth of 400 feet; though not as violent as the surface, these waves can cause a submarine to roll 5 to 10 degrees either way.

Overall, it seems SH4 is more accurate in how surface conditions affect a submerged submarine.
I think even SH1 reflected this sort of effect, of being able to dive a little ways (or a bit deeper in very heavy seas) so surface conditions did not affect a sub's speed. I recall some times finding it better to just dive and go submerged at minimal speed rather than wasting fuel on the surface with barely reaching 1/3 or 1/2 of the usual speed.

05-14-09, 09:32 PM

open the subs sim file and adjust the gc_height which is the center of gravity.

that will help you get more roll

mike_espo · 05-14-09, 10:13 PM

Quote:

Originally Posted by WEBSTER

open the subs sim file and adjust the gc_height which is the center of gravity.

that will help you get more roll

Sorry Webster. That only appears to work when surfaced....

Oh well. not too big a deal. Is nice though when your in a storm. Nice thing to do for the crew.

Stealhead · 05-15-09, 02:05 AM

Maybe in a huge storm youd need to go over 200ft to not feel much roll but i have read that most of the time about 100ft or so under a sub wont get much effect at all from surface condtions. makes since as as you get deeper water pressure goes up and that would resist movement at laest from the surface. That had to be a very huge strom and what would be considered normal would not apply to the story that mike mentioned. And I am not saying there would be no movement under water just no where near the amount that the boat would get on the surface. Pretty much US sailors just toughed out very rough weather only when it was considered too dangerous or the motion become a fatigue factor on the crew would they dive to avoid the roughness. In Take Her Deep the author mentions that while in a wolf pack they hit rough seas and a sailor on watch on another sub got killed when a wave smashed his binocs into his cheast so hard it crushed his diaphram and he died hours later from the pain and inabilty to breath properly.(not like they could have done anything to save his life)

mike_espo · 05-14-09, 09:36 PM

Quote:

Originally Posted by rditto48801

Waves are on the surface, a dived sub is 'below' the waves.
Why would a sub 'under' the waves be affected by them?

After doing a little googling, I found an FAQ page (apparently from the Royal Navy, relating to nuclear subs), but it seems to fit the subject at hand.
http://www.royalnavy.mod.uk/operatio...tFormat/print/
(near the bottom)

Overall, it seems SH4 is more accurate in how surface conditions affect a submerged submarine.
I think even SH1 reflected this sort of effect, of being able to dive a little ways (or a bit deeper in very heavy seas) so surface conditions did not affect a sub's speed. I recall some times finding it better to just dive and go submerged at minimal speed rather than wasting fuel on the surface with barely reaching 1/3 or 1/2 of the usual speed.

Sorry to disagree.

I refer you to the probably unfortunately out of print classic: The Boat By Lothar Gunther Buckheim.

During the Storm chapter, which was quite long, he states that the "old man" would dive the boat to give the crew a break-and he says that over 200 feet would be needed to stop the rolling/rocking motion from the angry seas above.

rditto48801 · 05-15-09, 04:02 AM

Quote:

Originally Posted by mike_espo

Sorry to disagree.

I refer you to the probably unfortunately out of print classic: The Boat By Lothar Gunther Buckheim.

During the Storm chapter, which was quite long, he states that the "old man" would dive the boat to give the crew a break-and he says that over 200 feet would be needed to stop the rolling/rocking motion from the angry seas above.

And I again point out what I had found online. Mainly this part
"In fact, during moderate storms the submarine remains level at its submerged depth while the waves crash above. In extremely violent storms, like hurricanes or cyclones, wave motion can reach to a depth of 400 feet; though not as violent as the surface, these waves can cause a submarine to roll 5 to 10 degrees either way."

To me hat is an indication that, unless weather gets really bad, it won't do much to a submerged sub, but that if weather gets really bad, a sub can still feel the effects to some degree when submerged, even if down a few hundred feet.
I am unsure if I have ever encountered a storm 'that bad' in SH4.

I think I have encountered that kind of weather in SH3... several times... waves so big the diesels die and you occasionally get waves tossing the sub up and down, occasionally a wave going up and over the conning tower as the sub is on a downward motion... It annoyed me that my crew can gleefully be on watch during those conditions, it seems like it would make sense in SH3 if they would come inside when constantly getting hit with waves that should technically sweep everyone off the conning tower... not like aircraft could fly (or even spot anything smaller than small to mid sized merchant/war ship) in such conditions anyways...
It was during such weather I noticed the sub seeming to have a mild 'roll' when even deep underwater.
But the again, isn't the English Channel known for heavy seas that can get so bad they sink ships?

AKULA_71 · 05-15-09, 06:27 AM

I know from personal experience a 688 SSN rolled quite alot @150ft depth when hurricane Bob was topside in Long Island Sound (1991). A lighter gato boat getting bounced around slightly while submerged deep in heavy seas isn't surpriseing at all.

In SH3 this was modled kinda close, even at 70m depth a type VII will move around slightly in heavy seas. On the other hand, in SH4 once under 60ft depth all hell could be breaking loose topside and one couldn't really tell in control.

PortsmouthProwler · 05-15-09, 02:40 PM

FACT: You could be in a rowboat 2,000 miles out at sea in the Pacific, and if a tsunami were travelling right through your location, you'd never know it - the 'wave' would be about six inches, tops.

Check out some basic physics. A wave in a medium such as water is highly misunderstood by most people. The compression and rarefaction of the particles (i. e., water molecules, in this case - also bear in mind that water is an incompressible fluid) is almost entirely imperceptible out at sea (and I mean well out at sea). The breakers and what most people think of as waves occur only when the bottom of the wave starts to hit a substance even more incompressible, i. e., land.

Das Boot is a work of fiction. As a Lit major, I'm all for poetic license, but recognize it for what it is.

* German boats were smaller than US fleet boats. A smaller vessel will be more affected by sea state.

* Where you are is crucial. I respect the opinion of a sub vet, but notice where the boat was - in Long Island Sound in a hurricane. Shallow and enclosed; even a modern 350' long behemoth with the tonnage of a WWII CV is going to roll at a shallow depth.

In general, submarines do not roll, pitch, or yaw greatly under 100'. Furthermore, as far as SH3 and SH4 go - a great deal of the action in 4 occurs in 'blue water', away from a continental shelf. A lot of the action in 3 is above a continental shelf. This is a significant difference in what you can expect for sea state and weather, so maybe the devs have modelled it much more reralistically than one might think.

05-14-09, 04:31 PM	#1
mike_espo Sonar Guy Join Date: May 2005 Location: Chicago, USA Posts: 396 Downloads: 12 Uploads: 0	Heavy seas and rolling motion I noticed in SH 3 how a u boat would toss and roll in heavy seas while submerged, even at depths of 200+ ft or so. However, in SH 4, a gale can be raging overhead and the boat is rock steady at periscope depth or about 50 feet or so. It seems that SH3 was more realistic in this regard. Is there a way to edit this somehow? thanks

05-15-09, 02:05 AM	#5
Stealhead Navy Seal Join Date: Feb 2009 Location: Kentucky Posts: 5,421 Downloads: 85 Uploads: 0	Maybe in a huge storm youd need to go over 200ft to not feel much roll but i have read that most of the time about 100ft or so under a sub wont get much effect at all from surface condtions. makes since as as you get deeper water pressure goes up and that would resist movement at laest from the surface. That had to be a very huge strom and what would be considered normal would not apply to the story that mike mentioned. And I am not saying there would be no movement under water just no where near the amount that the boat would get on the surface. Pretty much US sailors just toughed out very rough weather only when it was considered too dangerous or the motion become a fatigue factor on the crew would they dive to avoid the roughness. In Take Her Deep the author mentions that while in a wolf pack they hit rough seas and a sailor on watch on another sub got killed when a wave smashed his binocs into his cheast so hard it crushed his diaphram and he died hours later from the pain and inabilty to breath properly.(not like they could have done anything to save his life) Last edited by Stealhead; 05-15-09 at 02:16 AM.

05-14-09, 09:32 PM	#3
Webster Stowaway Posts: n/a Downloads: Uploads:	open the subs sim file and adjust the gc_height which is the center of gravity. that will help you get more roll

05-15-09, 06:27 AM	#8
AKULA_71 Swabbie Join Date: Jun 2005 Posts: 12 Downloads: 1 Uploads: 0	I know from personal experience a 688 SSN rolled quite alot @150ft depth when hurricane Bob was topside in Long Island Sound (1991). A lighter gato boat getting bounced around slightly while submerged deep in heavy seas isn't surpriseing at all. In SH3 this was modled kinda close, even at 70m depth a type VII will move around slightly in heavy seas. On the other hand, in SH4 once under 60ft depth all hell could be breaking loose topside and one couldn't really tell in control.

05-15-09, 02:40 PM	#9
PortsmouthProwler Bosun Join Date: Oct 2008 Posts: 65 Downloads: 11 Uploads: 0	FACT: You could be in a rowboat 2,000 miles out at sea in the Pacific, and if a tsunami were travelling right through your location, you'd never know it - the 'wave' would be about six inches, tops. Check out some basic physics. A wave in a medium such as water is highly misunderstood by most people. The compression and rarefaction of the particles (i. e., water molecules, in this case - also bear in mind that water is an incompressible fluid) is almost entirely imperceptible out at sea (and I mean well out at sea). The breakers and what most people think of as waves occur only when the bottom of the wave starts to hit a substance even more incompressible, i. e., land. Das Boot is a work of fiction. As a Lit major, I'm all for poetic license, but recognize it for what it is. * German boats were smaller than US fleet boats. A smaller vessel will be more affected by sea state. * Where you are is crucial. I respect the opinion of a sub vet, but notice where the boat was - in Long Island Sound in a hurricane. Shallow and enclosed; even a modern 350' long behemoth with the tonnage of a WWII CV is going to roll at a shallow depth. In general, submarines do not roll, pitch, or yaw greatly under 100'. Furthermore, as far as SH3 and SH4 go - a great deal of the action in 4 occurs in 'blue water', away from a continental shelf. A lot of the action in 3 is above a continental shelf. This is a significant difference in what you can expect for sea state and weather, so maybe the devs have modelled it much more reralistically than one might think.