SUBMARINEMUSEUMS.ORG Forum
General Boards => Submarine Related Chatter => School of the Boat => Topic started by: JTheotonio on November 01, 2008, 05:29:02 PM
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Here is a quick problem – on routine patrol on the surface a fast approaching aircraft is spotted and the captain orders an emergency dive.
In the control room, all vents are opened. Bow planes are rigged and put into a 22 deg dive. All outboard exhaust valves are shut, engine air induction and ship’s supply outboard valves are shut or checked shut.
Air is bleed into the boat, pressure in the boat is noted. Stern planes are put into dive to take ship to ordered depth of 100’ with 10 degree down bubble (normal is 4-6 degree) bow buoyancy vent is shut at 30 feet, and safety is open and shut for 5 seconds. Negative is flooded.
All bulkhead flappers are opened to resume normal ventilation. General quarters is announced sending the crew to their battle stations. Captain also orders a 90 degree course change turning the boat to the left, and orders the boat to full ahead.
As the boat is turning, increasing her speed, the down angle starts to rapidly increase is heading to 20 degrees down angle, but there is also now an increasing list to port, driving the bow down at an even larger down angle, which has driven the boat past 100 feet and she continues to go deeper. The list is increasing
What is wrong?
What actions must be taken? Name as many as you can think of
You must include the action to correct the primary cause of this situation, and an emergency method of correcting the problem.
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Really great forum. I'll take the first stab. Blow bow bouyancy, full rise on the bow and stern planes and back full. I'm thinking the list is from the rudder angle so you could zero the rudder but that would stop the turn and the bad guy could depth charge you. You could pump from Aux 2 to Aux, moving water from port to starboard. Another possibility is to blow the forward group for more lift forward. Any thoughts on that? You have to balance the added safety of the lift against having to vent it to avoid broaching later.
PS We on the Clamagore doing her living history program started a qual program and did our first school of the boat on her this past summer. We issued qual cards and notebooks to the guys. The easy part is studying the Fleet Boat manuals, it is the queen mother of bitches to try to map out systems when the tourons have stolen the handles and labels. Keep up the good work, I'm going to recomend that all of our people read this post because it is priceless. Terry Kuhn FTG1
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and some of the tourons were probably wearing dolphins...
You'd be amazed at the crap sailors have admitted to taking aboard memorial subs! Not all, but many more than you'd think!
:uglystupid2:
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Terry you got some good ideas, but did not find the problem.
Keep looking. Rudder angle on a fleet type submarine will not make a boat list as a nuc boat. At this point the boat was probably doing less than 8-10 knotts.
I'm heading to the airport on way to Atlanta - so if anyone gets the answer maybe Darrin can chime in. He knows what happened.
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I'm thinking that one of the starboard vents didn't open, causing the heavy list, but that doesn't explain the rapid descent... unless the straboard vent that is stuck closed is also aft of the bridge.
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Paul sure doesn't have many good things to say about submariners, does he! :-[
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Chief,
that is because an unnamed Torsk vet and submarine vet has threatened to remove parts from his beloved COD and bring them back to Torsk for use..... that and some of us sub vets have been known over the years to take part of their past home with them when they leave at the end of their tour, sadly that has probably happened to us more then we acutally know and blame on the kids and non sub vets.
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Hey Terry you didn't by chance ride a 688 in pearl in the early 90's did you? because your name is familiar and I can't remember why it sounds familiar
Darrin
TM3(SS) 718,717,711,692
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Sorry no, I was on the 619 from 83-85 and the 676 from 86 to 88 all on the east coast. Terry
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Don't worry about it Terry, always good to see a new face here.
Can you please bring Tom Sprowl with ya the next time you visit here on the bbs.. He is a shipmate of a shipmate of mine on Honolulu and from what I have seen and heard about him and from him he is trying like hell to save the Clamagore and doesn't have much help down there.
Let us know what we all can do to help if anything ;)
Darrin
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Okay, I'm like a tree, stumped. According to the Book OF All Knowledge, 16160, a typical 1500 ton fleet boat fully loaded on the surface draws 15' 6". Flooding the MBTs adds 359 tons and the bow bouyancy another 32 for a total of 2,141 and a draft of 22'. The safety adds 23 tons for a 24' draft and 55 tons in the variable tanks makes her neutrally bouyant. So by flooding the Negative (descriptive name) we make the USS Ustafish 8 tons negatively bouyant and she submerges. So, I can't see how any one of the #2 or #6 MBTs could be the problem, they hold about 32 and 35 tons each, enough to keep her on the surface. I also thought that all the MBTs in a group are piped to a common vent valve. If they have a pressure in the boat then they aren't getting water in the people tank. So, I will wear the Dink Non-qual hat of shame and take my turn in the scullery. Please enlighten me. Terry
PS This is really fun.
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Terry,
for the most part you have the corrective actions correct.. I.E. zero the rudder and go to full rise on the bow and stern planes and use a backing bell to correct hopefully your downward decent.. You and Mark both hinted at opening the MBT vents, which is another corrective action that should help get the air out of the tank that has the problem with the vent not opening causing a bad down angle..
Now folks which tank needs to be opened and why????
Terry, one of the first things we did during school of the boat is the layout of the tanks on a Balao so some of these folks have become REAL sharp when it comes to this one... And you are also correct for a nuke boat when you through the rudder to the left the boat goes down and when you toss it to the right the boat raises depending on how fast you are traveling at the time (snap rolls are fun!!!)
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Here I am in downtown Atlanta - $8 a drink, so I'm up in my room. I see by the coversations you are getting close.
I will tell you this - the problem you are solving actually occurred. Keep thinking - at the price for a drink in Atlanta I may get more time on the computer.
And yes this is fun!
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I noticed in the manual that there are list control dampers on the No. 2 and No. 6 MBTs. So, my guess is that the vents for either the 6a and 6c tanks or both may have gotten stuck and need to be opened. There are emergency vent valves that can be operated for each No. 2 and No. 6 tank.
Here's what the manual reads:
"The list control dampers are located at the Y-valve outlet connections on the 10-pound blow manifold. Both list dampers are attached to a shaft that runs through the manifold chamber. The shaft is operated by a hand lever at the after end of the manifold. The handle assembly consists of a push rod at the top of the handle, a handle, a spring, a latch, a name plate, and a bracket. A connecting rod attached to the handle is equipped with a turnbuckle secured with a bolt and nut. Pressing down the pushrod releases the spring, lifting the latch, and leaving the lever free to move inboard or outboard. As the shaft turns, the list dampers are swung to shut one port, or open both ports of the Y. The movement of the lever and the attached connecting rod turns the shaft by means of an offset arm. Outboard movement of the lever causes the damper to restrict the flow of air to the starboard side. Inboard movement of the lever causes the damper to restrict the flow of air to the port side. Normal position of the damper is neutral, allowing equal flow to both sides.
List control dampers control the flow of air to main ballast tanks 2B and 2D, 6B and 6D on the port side, and to main ballast tanks 2A and 2C, 6A and 6C on the starboard side."
Here's the process for specifically correcting Tanks 6a and 6c:
1. Open the emergency vent valve MBT No. 6A in the forward engine room on the starboard side.
2. Open the emergency vent valve MBT No. 6C in the forward engine room on the starboard side.
3. Open the supply flapper valve on the 10-pound MBT blow manifold.
4. Start the low-pressure blower.
5. Open the No. 6A-6C MBT 10-pound blow valve.
6. Shift the list control lever on the 10-pound blow manifold to starboard position to correct a port list.
7. Shift the list control lever to neutral position when the list is corrected.
8. Shut the MBT 10-pound blow valves upon completion of blowing.
9. Stop the low-pressure blower.
10. Shut the supply flapper valve on the 10-pound blow manifold.
11. Shut the emergency vent valve MBT No. 6C.
12. Shut the emergency vent valve MBT No. 6A.
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Now with what Mark has provided to us (and very accurate) which tanks could cause a down angle on the boat? Remember the layout of the tanks on the boat because if the tank is in the front of the boat won't it make the bow rise instead of go down???
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Any of the No. 6 MBTs filled with air, since they hold a lot of air (and water) compared to other tanks aft of the ship's center point. I guess aft trim tanks in the ATR that have too much air could also cause forward listing. The further back from the center point that you travel along the length of the boat, the less air that is required to cause a list. Large moment arms need less force to accomplish the same work as a short moment arm with a lot of force. The worst case scenario in my mind, though, would be No. 6C and/or 6D having vents stuck closed with air trapped inside the tanks.
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Mark,
you got the correct tank earlier, sorry I made you dig farther then you had to dig. Was trying to answer your post at work while I was WAY too busy to read all of the post that you had made about getting the #6 MBT vents open.. GREAT job all who participated in this part of school of the boat, looks like I will be in the Scullery this week after that mixup :-[
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Sitting here still in Atlanta early am waiting to start my meeting (half day then head home)
Good job on identify the problem. Stuck vents are allways a pain and it did happen on occasion. This problem would need to have been solved rather quickly as you can see the boat was going deeper - that was being driven by the steep down angle and the fact that the Captain ordered all ahead full on the dive.
Certainly the diving officer would have quickly asked that the vents be cycled, upon that failing, each compartment aft of the control room would have been looking for a problem. So in the mean time the Captain may have order all back full. There is a reason that he would not have ordered all stop - the propellers would still be turning so this would not have helped.
Other actions to be taken while the stuck vent was found and opened, would have been as you guys stated earlier, start pumping from aft trim, blow bow bouyancy, maybe blow negative, bow and stern planes to full up angle.
Well done everyone. I need to find the accident that occurred when such a problem almost caused an Argentine boat to sink - since it was one of our old fleet-type boats the problem was relative to this SOB on emergencies.
Now - I need to get focued on my meating
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I got the idea of stuck vents from watching Periscope Down. The first time that they dove the boat they had a list to port because one of the vents was stuck closed. :)
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It sounds like the answer was a stuck vent. I'm not 100% convinced that more air in an MBT would make you go down faster...I'd need to have that explained in more detail why.
The big picture as I saw it - you don't want to go up (enemy plane) or down (briny deep). Question - are you sinking or driving yourself down?
Slow down - backing bell for...10 seconds? then ahead at slow speed. Monitor depth as you do, if the depth change accelerates, blow tanks and go faster ahead because you're heavy and sinking. If the depth change slows down, you're driving yourself down due to something with the planes not being right.
If you're heavy, why?
tanks not at expected levels or have changed since last trim dive.
flooding in the FTR
I can't think of another source of weight that would cause that much heaviness forward.
If you're driving yourself down, why?
bow planes not actually rigged correctly.
Something else?
Remember that at this point you're on batteries and you don't have nuke style reaction ability on answering bells. If you ring up all back emergency on the batteries for too long, you're going to be surfacing again because your batteries are going to run down real fast.
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The excessive down angle was caused by the stuck shut vent on MBT #6 and with the captain ordering the fwd bell that he had ordered at the time, yes pumping water from fwd to aft will correct that problem while cycling all of the vents to make sure that there is no more air trapped in any of the tanks. Also using a backing bell will slow down if not stop the depth change assuming that there is no flooding,
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I'm going to try this -
Slow down - backing bell for...10 seconds? then ahead at slow speed. Monitor depth as you do, if the depth change accelerates, blow tanks and go faster ahead because you're heavy and sinking. If the depth change slows down, you're driving yourself down due to something with the planes not being right.
If you're heavy, why? You are diving, therefore the boat does have negative buoyancy, also remember that the boat is being driven down by the angle of the bow and stern planes, plus the turns for all ahead full. As long as the boat has a negative buoyancy it will go down. By filling the MBT's your boat should be in a neutral buoyancy (maybe a bit heavier).
tanks not at expected levels or have changed since last trim dive.
flooding in the FTR There was no flooding
I can't think of another source of weight that would cause that much heaviness forward.There was not additional weight
If you're driving yourself down, why? Typically the boat dives at ahead 2/3rd or less. Because of the urgency of getting under before the planes spotted the boat, the Captain did an emergency dive. Negative can be flooded to a mark (as blown), but in this case, negative was flooded, bow buoyancy was flooded, which is normal. To dive a boat you can stop dead in the water and do a control dive that would settle the boat without an angle, or you can dive with a down angle under power. Under power, with a down angle, will drive the boat under faster. In this emergency when the down angle rapidly increased, the boat would be driven down faster
bow planes not actually rigged correctly. Not a problem, if the planes could not be rigged properly it would have helped
Something else? nope
Remember that at this point you're on batteries and you don't have nuke style reaction ability on answering bells. If you ring up all back emergency on the batteries for too long, you're going to be surfacing again because your batteries are going to run down real fast. I did not throw this into the problem, but after a certain angle, your battery water would start coming out and this would cause a few other problems. Fires, toxic fumes, shorting of batteries, etc
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You are diving, therefore the boat does have negative buoyancy, also remember that the boat is being driven down by the angle of the bow and stern planes, plus the turns for all ahead full. As long as the boat has a negative buoyancy it will go down. By filling the MBT's your boat should be in a neutral buoyancy (maybe a bit heavier).
That's where I don't get it. If a vent was stuck causing a list, the list would not become apparent at deep depth, it should have been throughout the dive. The boat would be light aft and take a deeper angle, but if properly trimmed, it should be positively boyant with an a stuck vent and become nearly neutral when the #6 MBT is vented. I don't have the math on it, but my gut feeling is that if the bouyancy from the tank is stronger than the plane's ability to control the angle, then it won't be overcome by the screws. I could be wrong on that, its just a gut feeling.
The angle should happen right away, the dive is slower and the boat is harder to get down.
Brian