Sea State & Ship Motion - Page 2

bobchase · 07-07-08, 09:35 PM

Actually, I have always thought that the ships in SH3 are too stable in both pitch and roll, especially the non-combatants. With 15 m/s (30 knot) winds, the North Atlantic will easily build up 10 ft seas. Even with 3 footers that are widely spaced, a ship will pitch and roll because of the inertia of the ship and the irregular lift of the swells. When a ship lifts on a swell, the inertia of it's weight will often drive it down into the trough of the next swell or, worse, drive it into the next swell so that it can't lift it's bow. Ships do not willingly take seas directly on the bow becuase of this. When you quarter into a regular swell, like most ships do, then you are going to get some rolling action going.

Most videos you see of ships on the Internet grossly overstate the actual wave heights. They also tend to be hand held videos, which is a problem when you are trying to judge pitch and roll because humans tend to stand perpendicular when the deck pitches and rolls under them. When the horizon and the camera are both stable, then the acutal pitch and roll of the ship is hard to judge. Also, the videos taken from super-tankers and massive container ships cannot compare to what a 300 ft destroyer escort or even a 700 ft heavy cruiser will do in the same sea-state. They are just too big.

Take a look at these videos.

This one is of a small US Navy ship about the size of a WW2 Destroyer that highlines off of an oiler. The seas are small (3' - 5') but the oiler's foredeck is going right down to the sea and then pitching up until the bow is almost out of water. Also look at the amidships main deck draining water when the camera moves down the hull. By the way, the wave heights between the ships is caused by the Venturi effect from the ships - they are not indicative of the true sea-state. This is what summer looks like in the North Atlantic.

This one is from a tanker that is much bigger than anything in SH3. The video was taken in the Indian Ocean but those would be pretty calm seas in the North Atlantic and about average seas in the Pacific. Watch the railing against the horizon at the beginning of the video.

This is one is of a huge LPG tanker in a full gale. The seas look about about 8 - 10 ft and they are well defined, just like the SH3 sea always is. It's certainly not a confused sea like the North Atlantic is in the fall and winter months. I believe his degrees of roll that he puts in the super's and he is probably pitching 5 - 10 degrees. Watch the midships crane against the horizon.

I've made a few transits on freighters (mostly AO's and AOE's) going out from port to meet my ship. Even in relatively calm seas I'd go airborne in my bunk on the downward falls if I had to bearth way up forward. Once, on an AD (destroyer tender) I was assigned a top bunk. I thought 'how lucky can I get - a top bunk'. Then, as I climed up the other five bunks to get up to mine and looked back down, I thought 'Oh, I get it, these guys are afraid of nose bleeds - Ha-Ha'. Later that night we got into to a bit of rain storm of of Cape Hatteras. The third time my head hit the 12" deck beam that was about three feet above my head I got down and went aft to the mess decks and jsut stayed there. I think that big red crease in my forehead is still there...

Bob Chase

Sailor Steve · 07-07-08, 10:48 PM

I'm with bobchase, with a couple of qualifications. I have no problem with the motion of the ships, except that to me the larger ones move too quickly. Big ships get a lot of motion in the sea, but it should be more ponderous. I'm bothered by the number of ships that sink in bad weather, but is that the same thing as just disliking the motion. I also don't like the motion of ships in what should be sheltered harbors, but that's a problem of its own.

Here is an older one of a destroyer replenishing from a carrier. I like it because it's a Gearing, almost identical to the one I was on. I remember doing the same thing, and in about the same weather.

For the most part, I think it works just fine.

AOTD_MadMax · 07-08-08, 07:51 AM

In SH4 i have only reworked the UD Drags and the GC-height and all looks fine.

The problem is that you cant choose only one setting for all Units
Each ship needs different settings if you wanne have it realistic !
So it is an hard work to find out the right settings for each ship.

Greets

Maddy

Jhereg · 07-08-08, 12:14 PM

Gonna have to agree with Bobchase and Sailor Steve, our current Destroyers are larger and significantly better handling then WWII destroyers. I was most recently on USS Normandy CG 60 and going up forward to the sonar trunk was always fun in even moderate seas. You could skip decks going up if you timed your jump/scramble up the ladder with the downward pitch of the bow into the trough of the swell. Definitely sleep well when underway as the constant rocking even in light seas sure is nice.

07-07-08, 10:48 PM	#17
Sailor Steve Eternal Patrol Join Date: Nov 2002 Location: High in the mountains of Utah Posts: 50,369 Downloads: 745 Uploads: 249	I'm with bobchase, with a couple of qualifications. I have no problem with the motion of the ships, except that to me the larger ones move too quickly. Big ships get a lot of motion in the sea, but it should be more ponderous. I'm bothered by the number of ships that sink in bad weather, but is that the same thing as just disliking the motion. I also don't like the motion of ships in what should be sheltered harbors, but that's a problem of its own. Here is an older one of a destroyer replenishing from a carrier. I like it because it's a Gearing, almost identical to the one I was on. I remember doing the same thing, and in about the same weather. For the most part, I think it works just fine. __________________ “Never do anything you can't take back.” —Rocky Russo

07-08-08, 07:51 AM	#18
AOTD_MadMax Seasoned Skipper Join Date: Jun 2007 Location: Bremen/Germany Posts: 749 Downloads: 71 Uploads: 1	In SH4 i have only reworked the UD Drags and the GC-height and all looks fine. The problem is that you cant choose only one setting for all Units Each ship needs different settings if you wanne have it realistic ! So it is an hard work to find out the right settings for each ship. Greets Maddy __________________ AOTD is gone, iam the last survivor ........

07-07-08, 09:35 PM	#16
bobchase Torpedoman Join Date: Jan 2008 Location: Pearland, Texas Posts: 118 Downloads: 21 Uploads: 0	Actually, I have always thought that the ships in SH3 are too stable in both pitch and roll, especially the non-combatants. With 15 m/s (30 knot) winds, the North Atlantic will easily build up 10 ft seas. Even with 3 footers that are widely spaced, a ship will pitch and roll because of the inertia of the ship and the irregular lift of the swells. When a ship lifts on a swell, the inertia of it's weight will often drive it down into the trough of the next swell or, worse, drive it into the next swell so that it can't lift it's bow. Ships do not willingly take seas directly on the bow becuase of this. When you quarter into a regular swell, like most ships do, then you are going to get some rolling action going. Most videos you see of ships on the Internet grossly overstate the actual wave heights. They also tend to be hand held videos, which is a problem when you are trying to judge pitch and roll because humans tend to stand perpendicular when the deck pitches and rolls under them. When the horizon and the camera are both stable, then the acutal pitch and roll of the ship is hard to judge. Also, the videos taken from super-tankers and massive container ships cannot compare to what a 300 ft destroyer escort or even a 700 ft heavy cruiser will do in the same sea-state. They are just too big. Take a look at these videos. This one is of a small US Navy ship about the size of a WW2 Destroyer that highlines off of an oiler. The seas are small (3' - 5') but the oiler's foredeck is going right down to the sea and then pitching up until the bow is almost out of water. Also look at the amidships main deck draining water when the camera moves down the hull. By the way, the wave heights between the ships is caused by the Venturi effect from the ships - they are not indicative of the true sea-state. This is what summer looks like in the North Atlantic. This one is from a tanker that is much bigger than anything in SH3. The video was taken in the Indian Ocean but those would be pretty calm seas in the North Atlantic and about average seas in the Pacific. Watch the railing against the horizon at the beginning of the video. This is one is of a huge LPG tanker in a full gale. The seas look about about 8 - 10 ft and they are well defined, just like the SH3 sea always is. It's certainly not a confused sea like the North Atlantic is in the fall and winter months. I believe his degrees of roll that he puts in the super's and he is probably pitching 5 - 10 degrees. Watch the midships crane against the horizon. I've made a few transits on freighters (mostly AO's and AOE's) going out from port to meet my ship. Even in relatively calm seas I'd go airborne in my bunk on the downward falls if I had to bearth way up forward. Once, on an AD (destroyer tender) I was assigned a top bunk. I thought 'how lucky can I get - a top bunk'. Then, as I climed up the other five bunks to get up to mine and looked back down, I thought 'Oh, I get it, these guys are afraid of nose bleeds - Ha-Ha'. Later that night we got into to a bit of rain storm of of Cape Hatteras. The third time my head hit the 12" deck beam that was about three feet above my head I got down and went aft to the mess decks and jsut stayed there. I think that big red crease in my forehead is still there... Bob Chase

07-08-08, 12:14 PM	#19
Jhereg Electrician's Mate Join Date: Jul 2007 Location: Suffolk, Virginia Posts: 135 Downloads: 0 Uploads: 0	Gonna have to agree with Bobchase and Sailor Steve, our current Destroyers are larger and significantly better handling then WWII destroyers. I was most recently on USS Normandy CG 60 and going up forward to the sonar trunk was always fun in even moderate seas. You could skip decks going up if you timed your jump/scramble up the ladder with the downward pitch of the bow into the trough of the swell. Definitely sleep well when underway as the constant rocking even in light seas sure is nice.