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Bubblehead Nuke · 12-01-07, 03:01 PM

There are many factors that determine ships speed at the surface interface.
Primary factors are:

1) Initial ships speed

2) Initial Depth

3) Rate of bouyancy change

4) Angle on the boat

Lets break them down starting with an ideal system where we are only worried about going up with no casualities:

The inital speed of the boat during an emergency surface is going to effect the final speed. It is more than a simle additive function. The faster you are going the faster you are going to effect a depth change due to the effectiveness of the planes. It will effect the vector change in ships direction and thus have a quantifable change on the other vectors to be listed.

The deeper you are the more speed you have to gain. Why? This is due to having a longer change in bouyancy and a longer speed vector (dependant on initial speed). As the bouyancy increases (see next factor for why this happens) you are going to be gaining speed and thus the longer you have for this to happen the bigger increase you are going to have.

Rate of change of bouyancy is a REAL mind twister. Lets start with some basics.
The deeper you are, the less bouyancy you have. This is due to the compression of the hull due to increasing sea pressure. This is due to a decrease in surface area. Thus as you go shallow, you will gain positive bouyancy and vice versa.
Air in the high pressure flasks has to push against sea pressure to make it into the main ballast tanks. This means that the deeper you are, the LESS air is put into the tanks initially. Also, the air will lose volumn as the depth increases, thus a pound of air at 1000 feet is much less VOLUMN (hence bouyancy) than at say 150 feet. This it due to the surrounding sea pressure. As you go up, the RATE of air going into the main ballast tanks will increase due to decreasing sea pressure. The air will also EXPAND in the main ballast tank as you go shallow thus increasing the rate at which water is expelled from the main ballast tanks thus increasing the amount of positive bouyancy as you approach the surface.

As you can see, the amount of positive bouyancy addition starts small, but increases rapidly as you go up.

Angle on the boat is difficult to explain. The higher the angle, the faster you approach the surface, too steep and you can actually "tailslide' right back down after you pierce the surface interface as the ship can not 'tip over' fast enough to stay on the surface. This means you have to be aggressive to get up, but not TOO aggressive or you might go right back down. One of the limiting factors is that if you are TOO steep, you let the air out of the bottom of the ballast tanks and that is NOT want you want to do it you WANT to stay on the surface.

One thing you might not know, AFTER you surface you do not stay there. You sink back down then come back up again. The amount of depth that you go down is dependant on the intial depth of the boat (think INTERIA). It is not like the old WWII diesel boats that popped up, tipped over and then stayed on the surface. Oh no... You BLAST up and out.. make a HUGE wave.. then disappear horizontaly down. Then you pop back up and well.. 'bob' on the surface for a few seconds until you are stable on the surface.

----------------------------------------------------------------------------------------------------------------

Time to discuss other operational factors.

You can do an EMBT blow from a slow speed while shallow and just let the boat go up. You can being doing a standard bell, order an Emergence surface and do things by the book. This means answering a preset bell, order a sudden rise to a preset angle, and thus make the whole evolution go MUCH faster. These are things that you can not tell from the video. You do not know the inital factors and HOW the EMBT was ordered. This will greatly effect the final ships speed and how it looks on the surface.

At the start, I said lets do this in a ideal system. Now, lets add some factors so you can see how each of the factors interact with each other and WHY they are so important to know.

Flooding:

Water is heavy. Water in the people tank is BAD. When you are flooding you are DECREASING the bouyancy of the boat. The deeper you are the FASTER the water comes in. Think of your water hose and your lawn. The more pressure (the more you open the valve) the MORE water you get. Sea pressure is your valve.

In flooding you want to get shallow. This means pointing the boat in the proper direction. The slower you are going initially, the longer it is going to take the boat to respond to the Helmsman yanking back on the yoke in ships control to try and attain a specific preset up-angle.

To counter this, the throttlman is going to increase the ships bell automatically. This increases the speed of the boat and makes the Helmsman job easier by making his planes more effective. You also now have the HUGE propellor PUSHING you up.

This is the inital response to ANY flooding call.

This is CRITICAL desision time. The OOD has to wonder: Is the water coming in faster than the pumps have get rid of it? Is the IN-RATE of seawater flow slowing down fast enough to so that I can still get up to handle this. Remember, the DEEPER you are, the FASTER this is all happening. You may only have a few seconds to think this thru. You also have to have in mind WHERE the flooding is coming from. Is it from the Engine room? If so, this is going to possibly effect his ability to increase speed. This could effect his helmsmans ability to control the ship. This could GREATLY hamper the ability of the boat to recover from flooding. Is it in the torpedo room? This is going to add LOTS of mass in the front of the boat which is going to make it difficult to point the nose UP.

He makes a decision.. Emergency Surface.

The air starts to blow, the ships going up, but is it fast enough? Is the decrease of depth fast enough to give the air time to get into the ballast tanks? Are we losing too much bouyance due to the water we are taking on?

Only now is the REST of the crew starting to respond. The Helmsman and the throttlemans response are about the ONLY things that can be done quickly. The COW can hit the EMBT switches fast as well but it takes TIME for the bouyancy to change once he hits them. The REST of the recovery effort takes TIME. Time that you might not have depending on the severity of the situation.

My experience??:

You want to talk adrenalin?? NO drug could make you go into hyperspeed this fast. I have stood throttleman when the CO decided to have an unannounced flooding drill in engine room lower level in the middle of the backwatch (00:00 - 06:00). We were deep and we did things like they were for real. It was SCARY. Your heart THUMPS and you do your job. You KNOW that you one of THREE people who is now holding the lives of ALL your shipmates in your hands. Just before we surfaced I saw the ships speed indicator and I could not believe how fast we were going. It was the best carnival ride in the world. Once we were informed that it was a drill, the laughter started, and then we went about our business as usual.

The purpose of this post??

I will lay odds that the sub in question started no deeper than 300 feet from a low bell and a standard EMBT blow angle. I base this on the sinkout and recovery from the EMBT blow.

12-01-07, 03:01 PM	#4
Bubblehead Nuke XO Join Date: Feb 2006 Posts: 435 Downloads: 5 Uploads: 0	There are many factors that determine ships speed at the surface interface. Primary factors are: 1) Initial ships speed 2) Initial Depth 3) Rate of bouyancy change 4) Angle on the boat Lets break them down starting with an ideal system where we are only worried about going up with no casualities: The inital speed of the boat during an emergency surface is going to effect the final speed. It is more than a simle additive function. The faster you are going the faster you are going to effect a depth change due to the effectiveness of the planes. It will effect the vector change in ships direction and thus have a quantifable change on the other vectors to be listed. The deeper you are the more speed you have to gain. Why? This is due to having a longer change in bouyancy and a longer speed vector (dependant on initial speed). As the bouyancy increases (see next factor for why this happens) you are going to be gaining speed and thus the longer you have for this to happen the bigger increase you are going to have. Rate of change of bouyancy is a REAL mind twister. Lets start with some basics. The deeper you are, the less bouyancy you have. This is due to the compression of the hull due to increasing sea pressure. This is due to a decrease in surface area. Thus as you go shallow, you will gain positive bouyancy and vice versa. Air in the high pressure flasks has to push against sea pressure to make it into the main ballast tanks. This means that the deeper you are, the LESS air is put into the tanks initially. Also, the air will lose volumn as the depth increases, thus a pound of air at 1000 feet is much less VOLUMN (hence bouyancy) than at say 150 feet. This it due to the surrounding sea pressure. As you go up, the RATE of air going into the main ballast tanks will increase due to decreasing sea pressure. The air will also EXPAND in the main ballast tank as you go shallow thus increasing the rate at which water is expelled from the main ballast tanks thus increasing the amount of positive bouyancy as you approach the surface. As you can see, the amount of positive bouyancy addition starts small, but increases rapidly as you go up. Angle on the boat is difficult to explain. The higher the angle, the faster you approach the surface, too steep and you can actually "tailslide' right back down after you pierce the surface interface as the ship can not 'tip over' fast enough to stay on the surface. This means you have to be aggressive to get up, but not TOO aggressive or you might go right back down. One of the limiting factors is that if you are TOO steep, you let the air out of the bottom of the ballast tanks and that is NOT want you want to do it you WANT to stay on the surface. One thing you might not know, AFTER you surface you do not stay there. You sink back down then come back up again. The amount of depth that you go down is dependant on the intial depth of the boat (think INTERIA). It is not like the old WWII diesel boats that popped up, tipped over and then stayed on the surface. Oh no... You BLAST up and out.. make a HUGE wave.. then disappear horizontaly down. Then you pop back up and well.. 'bob' on the surface for a few seconds until you are stable on the surface. ---------------------------------------------------------------------------------------------------------------- Time to discuss other operational factors. You can do an EMBT blow from a slow speed while shallow and just let the boat go up. You can being doing a standard bell, order an Emergence surface and do things by the book. This means answering a preset bell, order a sudden rise to a preset angle, and thus make the whole evolution go MUCH faster. These are things that you can not tell from the video. You do not know the inital factors and HOW the EMBT was ordered. This will greatly effect the final ships speed and how it looks on the surface. At the start, I said lets do this in a ideal system. Now, lets add some factors so you can see how each of the factors interact with each other and WHY they are so important to know. Flooding: Water is heavy. Water in the people tank is BAD. When you are flooding you are DECREASING the bouyancy of the boat. The deeper you are the FASTER the water comes in. Think of your water hose and your lawn. The more pressure (the more you open the valve) the MORE water you get. Sea pressure is your valve. In flooding you want to get shallow. This means pointing the boat in the proper direction. The slower you are going initially, the longer it is going to take the boat to respond to the Helmsman yanking back on the yoke in ships control to try and attain a specific preset up-angle. To counter this, the throttlman is going to increase the ships bell automatically. This increases the speed of the boat and makes the Helmsman job easier by making his planes more effective. You also now have the HUGE propellor PUSHING you up. This is the inital response to ANY flooding call. This is CRITICAL desision time. The OOD has to wonder: Is the water coming in faster than the pumps have get rid of it? Is the IN-RATE of seawater flow slowing down fast enough to so that I can still get up to handle this. Remember, the DEEPER you are, the FASTER this is all happening. You may only have a few seconds to think this thru. You also have to have in mind WHERE the flooding is coming from. Is it from the Engine room? If so, this is going to possibly effect his ability to increase speed. This could effect his helmsmans ability to control the ship. This could GREATLY hamper the ability of the boat to recover from flooding. Is it in the torpedo room? This is going to add LOTS of mass in the front of the boat which is going to make it difficult to point the nose UP. He makes a decision.. Emergency Surface. The air starts to blow, the ships going up, but is it fast enough? Is the decrease of depth fast enough to give the air time to get into the ballast tanks? Are we losing too much bouyance due to the water we are taking on? Only now is the REST of the crew starting to respond. The Helmsman and the throttlemans response are about the ONLY things that can be done quickly. The COW can hit the EMBT switches fast as well but it takes TIME for the bouyancy to change once he hits them. The REST of the recovery effort takes TIME. Time that you might not have depending on the severity of the situation. My experience??: You want to talk adrenalin?? NO drug could make you go into hyperspeed this fast. I have stood throttleman when the CO decided to have an unannounced flooding drill in engine room lower level in the middle of the backwatch (00:00 - 06:00). We were deep and we did things like they were for real. It was SCARY. Your heart THUMPS and you do your job. You KNOW that you one of THREE people who is now holding the lives of ALL your shipmates in your hands. Just before we surfaced I saw the ships speed indicator and I could not believe how fast we were going. It was the best carnival ride in the world. Once we were informed that it was a drill, the laughter started, and then we went about our business as usual. The purpose of this post?? I will lay odds that the sub in question started no deeper than 300 feet from a low bell and a standard EMBT blow angle. I base this on the sinkout and recovery from the EMBT blow.