Bulkheads

[CaptainMattJ.]

Ive been thinking lately. I dont know exactly what im talking about, but it makes sense to me somewhat.

Wouldnt a higher shot, say as close to the waterline as possible, flood the ship better then a keel/ lower shot.

Think about it. A shot made at the waterline makes a hole that half extends to the part of the ship thats above water and half underwater. (roughly)

That hole starts flooding that deck immediately. But this where i think i could be right or wrong. Wouldnt the deck you hit start spilling water into all the lower decks as well? say you have ship with A-G Decks. Your waterline shot hits say D deck. wouldnt the water spill into E F and G decks at least?

As opposed to a low shot made at F deck which would spill into G deck filling the boat with less water therefore making it less likely to sink.

The weight from D E F and G decks would easily make the ship's density over 1 and cause it to sink right?

But this is just a slightly undereducated thought. But where i dont know too much is if each deck was in itself a watertight compartment. As in if D deck floods it has no way of reaching other decks. BUT wouldnt that sort of....cut off people from reaching E f and G decks?

So im actually somewhat asking a question. were at least MERCHANTS equipped with independent water tight decks.


And if im right, how come making a waterline shot in SH5 actually worse then shooting for the keel?

[TheDarkWraith]

the game engine has 'boxes' that model the ship's compartments. Let's say a box extends above and below the waterline. Now let's say you shell that compartment below the waterline. Let's also say that the shell induced enough damage in the compartment to start flooding. Now the game engine will flood that entire compartment over the time specified * (%damage incurred/maximum HP for compartment) - laymens terms. The more damage you incur to that compartment the faster it will flood.
The only way to model floors and watertight doors is to completely redo ALL the ship's boxes which is one hell of an undertaking :yep:
It's bad enough just adding some new boxes for flooding and capsizing with my FX_Update mod :shifty:

[CaptainMattJ.]

the game engine has 'boxes' that model the ship's compartments. Let's say a box extends above and below the waterline. Now let's say you shell that compartment below the waterline. Let's also say that the shell induced enough damage in the compartment to start flooding. Now the game engine will flood that entire compartment over the time specified * (%damage incurred/maximum HP for compartment) - laymens terms. The more damage you incur to that compartment the faster it will flood.
The only way to model floors and watertight doors is to completely redo ALL the ship's boxes which is one hell of an undertaking :yep:
It's bad enough just adding some new boxes for flooding and capsizing with my FX_Update mod :shifty:
oh, i wasnt necessarily asking for a mod, i was just testing a theory...

[Sailor Steve]

Merchants have very few actual decks. The engine and boiler rooms are large open spaces, several decks tall. The cargo holds extend from the keel to the weather deck.

http://www.jajones.com/pdf/Liberty_Ships_of_WWII.pdf

Scroll down to page 4 and you'll see a nice profile.

Also, hitting exactly on the waterline is nearly impossible. The target is rolling. Your boat is rolling. I've quoted Peter Padfield's description in the past: "Naval gunnery can be likened to shooting at a golf ball rolling across a mantle with a pistol, while sitting in a rocking chair being rocked at random by someone else."

[johan_d]

"Naval gunnery can be likened to shooting at a golf ball rolling across a mantle with a pistol, while sitting in a rocking chair being rocked at random by someone else."

If this is the case, then most cannon shots in SH shouldnt be accurate as is now ?

[Sailor Steve]

Padfield's comment was actually referring to capital ships with sophisticated gun directors and fire control systems. The average overall hit rate for naval combat was about 7%.

I don't have SH5, but in previous incarnations the gunfire is much too accurate. At 1000 meters on a perfectly calm day you should be hitting a large target most of the time, but as soon as the boat starts rocking at all you should be hitting about 20% of the time. A u-boat has no fire-control system at all, just the tube sight mounted to the gun, which is mounted to the deck, which is in constant motion. A merchant ship is larger and has less motion, but the u-boat is a smaller target, so theirs shouldn't be much better.

[Not_Yet _Kameraden]

This is just my guess, but a keel shot would be used to damage compartments in the middle. Also the explosion would push everything up damaging the more vital components of the ship (like the engine room). Because you have less compartments to blast through when coming from underneath, which i some cases would blast a hole right through the whole ship.

Unless I,m totally wrong.

[reignofdeath]

I think your overthinking it a bit. If they didnt have water tight decks then a shot above the waterline might flood it more, however, look at the word waterline this means that due to the wave action in the sea that above that imaginary mark, not alot of water would get the chance to spill in through that hole, so a shot half in and half out of the waterline would flood the ship faster due to being in contact with the water (Half of the hole underwater and half out lets say). Also you got to take into account where the shot is, if its in the bow of a ship moving at say 10kts, youd end up getting MORE water in through the hole due to the effect that the ship is moving and litterally scooping water into itself.

As far as a keel shot being more effective, for one if its an impact, the hole ends up being completely underwater. For magnetics however, the detonation under the ship causes a rapid pressure change and ruptures the bulkheads, then causes all the water that was blown away by the explosion (Remember this explosion creates a "Void" and one of the key fundamentals of physics/ chemistry is matter always (or mostly) goes to the path of least resistance, therefore, if there is an area devoid of matter, all the matter around it will try to fill it up) will be sucked back in and right up into the hole it created creating immense flooding.

Hope thats what you were looking for, didnt really understand your question outright.


Casey

EDIT: I re read and understood your post, disregard the first paragraph of my post, I thought you were talking about a shot ABOVE the waterline.

[Sailor Steve]

And I start to think I got the wrong impression in the first place. Are we talking about torpedoes? If that's the case, then no, hitting exactly on the water line is not more effective, for the simple reason that a hole completely beneath the waterline lets in more water, and the blast from a torpedo tends to rupture bulkheads and decks all around it anyway.

A keel shot doesn't necessarily do more damage than any other hit. It's advantage is that the shock wave coming from directly beneath the ship has a good chance of actually cracking the keel itself, in which case the hull can't hold itself together and the ship breaks apart, and the job is done.

[CaptainMattJ.]

well i was thinking at maybe a couple meters below the waterline type of sot. But really i was asking more about the effect of flooding.

but say you DID make a keel shot, and the entire engine Deck/Space/whatever was flooded.

But, lets say this wasnt enough. Youd then have to fire another torpedo or beat it up with your deck gun. BUT, say a torpedo fired higher up slammed into a deck that was slightly below the waterline. Now what i was thinking that would contribute to more effective flooding was 3 things

1) that the suction created by the fact that the hole was half-half in terms of the waterline, and that the suction created by that kind of hole when it was very close to being engulfed in water would make flooding faster, leaving less time for the crew to react.

2) with less time, the deck members would have less time and a greater risk of isolation from the water spilling in to that one deck and then going down through the decks /engine space to close of a theoretically "seal-able" deck.

3) IF the flooding of roughly most of the decks at/below the hole werent enough to sink it, it was drag the ship down to the point where the deck and/or decks below it would flood because they were then underwater after being dragged down.

But you DID shine some light.. I didnt take into account the fact that the shockwave from the torpedo alone would being enough to rupture the relatively thin in comparison bulkheads.

[Webster]

well water pressure must be considered as well, at the waterline you have slightly less pressure of the water force pushing into the hull yet as you go lower it gets higher so as you sink and the hole gets lower in the water the flow into that hole would be under more pressure and be slightly higher.

its nothing hugely dramatic but the pressure from being under water can increase flow into any opening that isnt maxed out at full capacity already and conversly the closer to waterline the more likely that a hole wouldnt be maxed out at full rate that "could" enter such a hole.

other variables like tonnage go into how much force the water has against the hull but as to your thoughts on a waterline breach having more flow then one under water that isnt the case as i just described the reasons why. if anything its most likely a waterline breach would be having less flow then one under water unless the ship were loaded to the extent they would be the same.

[Sailor Steve]

but say you DID make a keel shot, and the entire engine Deck/Space/whatever was flooded.
As USNSRCaseySmith said, you're overthinking it. Nothing is that precise, and they didn't think that way.

But, lets say this wasnt enough. Youd then have to fire another torpedo or beat it up with your deck gun. BUT, say a torpedo fired higher up slammed into a deck that was slightly below the waterline. Now what i was thinking that would contribute to more effective flooding was 3 things

1) that the suction created by the fact that the hole was half-half in terms of the waterline, and that the suction created by that kind of hole when it was very close to being engulfed in water would make flooding faster, leaving less time for the crew to react.
First, to hit "half-half" the torpedo would have to be on the surface, which is impossible. If the torpedo is too shallow you run the risk of a breach and the torpedo is lost. Second, the flooding is not going to be faster. If the hole is half out of the water, then only half as much water is going to come in, until the ship settles enough and the hole is entirely underwater, which is what you wanted in the first place.

It seems to me you're thinking that the higher hole would let water wash down, whereas a lower hole would not. As I said, the point of hitting under the keel is to break the keel, not let more water in. Any hole in the side is going to allow water to go in every direction, and lateral is as good as down.

2) with less time, the deck members would have less time and a greater risk of isolation from the water spilling in to that one deck and then going down through the decks /engine space to close of a theoretically "seal-able" deck.
A torpedo hole is not tiny. Bulkheads for many yards around are ruptured. At best any crew not incapacitated by the blast are going to be busy making what repairs they can. There is no such thing as 'Theoretically "seal-able". All doors are watertight, and in a war zone are already sealed. The torpedo is designed to cause a big enough blast to rupture everything around it, and the damage done is the damage done. No water is going to "wash down" to the lower decks. Ever.

3) IF the flooding of roughly most of the decks at/below the hole werent enough to sink it, it was drag the ship down to the point where the deck and/or decks below it would flood because they were then underwater after being dragged down.
It doesn't work that way. See my answer to (2).

But you DID shine some light.. I didnt take into account the fact that the shockwave from the torpedo alone would being enough to rupture the relatively thin in comparison bulkheads.
Not thin at all. The bulkheads are the same thickness as the hull. They hold the ship together. Also, the shockwave is what does all the damage, since water doesn't compress. The explosion itself just sets off the shock.

[Shandiir]

Also for every meter down adds more water pressure to the hole, so a hole at the waterline won't have the pressure behind it to compress the air in the chamber. A hole 4 meters down has 4 times the pressure the waterline does. So the water enters the space faster (higher flow rate). Now this adds to the weight of the ship eg 10,000 ton ship now has 300 ton of water or balast, it pust more pressure on the balkheads. If these were stressed or damaged from the impact now they fail. The best the game does is make a ship take hours to sink as it takes on water and reduced hits points.

A shot at the water line does less damage and less water into the ship, so the ship should sink slower.

Now hit the ship with a deck gun and open air holes for the compressed air to escape and watch that baby sink faster! Of cause none of this is done in game.

[reignofdeath]

Too bad. Question for you though Steve, seeing as you know more about the physics of a magnetic shot than I do. Was I somewhat right in the explanation I gave about extended flooding due to their also being a "void" area where the water once was?? My reasoning is that the water all around rushes right back and then into the new hole in a geyser like fashion or
is it JUST the shockwave from the magnetic shot that's effective???

[Sailor Steve]

I actually know very little offhand, but I've had the privilege of being on a website that was frequented by those who have done the primary work. Nathan Okun is acknowledged as the leading expert in the world on shell ballistics and the effects of explosions, as well as how armor works. Here is his explanation:
http://www.navweaps.com/index_tech/tech-026.htm

Follow the "Back To" link at the bottom of the page to find a gold mine of naval information, mostly written by the people who know.

[reignofdeath]

Alright, thank you very much!