Back Emergency to Slow down

drhyed · 12-31-17, 11:13 AM

So when Your going across the Big map moving to mission areas and run into an unexpected enemy at 20 knots it takes a bit of time to slow down and for the sensors/sonar to work. I can slow down in a hurry by going to back emergency, I been on boats where this has been done and it makes big wakes, disturbances, and air bubbles. Anyone know if Im setting off signal flairs and laying out the welcome mat for the Russians doing this? With the new update I am still doing alright with subs but surface encounters are still giving me trouble so its hard to tell, I dont get cavitation warnings, anyone know?

Thanks
Jay

THEBERBSTER · 12-31-17, 11:29 AM

A Warm Welcome To The Subsim Community > drhyed
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Killerfish Games · 12-31-17, 07:42 PM

You're not giving away yourself. You are rapidly decelerating so your flow noise and engine noise will decrease quickly.

Capt.Hunt · 01-01-18, 03:29 AM

I'm sure one of our resident submariners could give us a definitive answer, but you'd think going all back emergency would make a heck of a racket. After all, the screw is only optimized to turn one way, and the pumps would probably shift to high speed.

ET2SN · 01-01-18, 03:52 AM

I guess it depends.

Real world, its not like you're shifting gears from the helm.
All you're doing is turning the dial on the announceator which makes the pointer move on a similar dial back in Maneuvering.
Its up to the throttleman to see the new order and turn the "big wheel" to drive the screw, just like when you give a spoken order to "make turns for X knots".

So, I guess you can assume that you have a sharp throttleman back aft who knows you want to slow down fast.

drhyed · 01-01-18, 10:19 AM

In thinking about it more the screw is attached to a electric motor and with an electric motor you can use induction to instantly reverse the polarity, which then works like a giant brake on the motor at the expense of heat generation ( I think? going off of my very limited knowledge of how trains work and driving a Prius

) just flip the switch on the side of a ceiling fan when its spinning on high to see what Im referencing, now image if your ceiling fan blades were in water, consider how quickly they would slow down. Im sure with some testing at a place like the The Navy's Acoustic Research Detachment in Idaho they could work out a chart which got me down below 10 knots with the best risk vs reward for noise crated vs the disturbance I made in the water. Of course it would probably be contained in a chart with a million curves and lines for each 25 feet of depth and each 2 knots of speed I was going and require the use of a slide rule to decipher but thats part of reward of being a sub captain!

Bubblehead Nuke · 01-01-18, 11:08 PM

Quote:

Originally Posted by Capt.Hunt

I'm sure one of our resident submariners could give us a definitive answer, but you'd think going all back emergency would make a heck of a racket. After all, the screw is only optimized to turn one way, and the pumps would probably shift to high speed.

Yes.. it makes one HELL OF A LOT OF NOISE. HUGE "HERE I AM" TRANSIENT NOISES.

In reality you slam the forward throttle closed and open the astern throttle rapidly without regard to cavitation. You do not shift pumps unless ordered. You will answer the bell to the maximum limit of the current plant lineup.

This spins the screw in the opposite direction creating HUGE amounts of cavitation. The idea is that you are gonna hit something anyway and you can at least try to cut down on the damage done in the collision.

While I am on this tangent, if you want to slow down you ring up all stop. The boat will continue in the water but the screw will act as a brake. It is still turning but the drag of the water will slow the boat down. Think of it as coasting in a car. Drag will slow you down. You never, NEVER, NEVER open the astern throttles unless you are in an emergency, docking, or are in restricted maneuvering operation.

But hey.. its a game.

ET2SN · 01-02-18, 02:07 AM

Quote:

Originally Posted by Bubblehead Nuke

But hey.. its a game.

It sounds like we're both talking about "Crash Backs".

I had a buddy who was standing throttleman watch after we finally got good old Ustafish out of a long overhaul.
Our skipper had been talking about doing crash back drills so up in Control it wasn't that big of a surprise when the OOD ordered a backing bell while we were cruising along.
I guess the skipper didn't like the reaction time (putting it mildly) and he set a speed record sprinting from Control to Manuvering.

Allegedly, our skipper took control of the throttles manually while he chewed out my bud and the RO.

Now, anyone who ever stood watch back aft or made it through quals in general can say, "Hey, that part of the story IS REALLY MESSED UP!!" and you would be right.

Getting back on topic, yeah you could order a backing bell IRL if the situation is dire enough but we're talking about a game where the whole point is to beat the Devs.

12-31-17, 11:13 AM	#1
drhyed Swabbie Join Date: Dec 2017 Posts: 9 Downloads: 12 Uploads: 0	Back Emergency to Slow down So when Your going across the Big map moving to mission areas and run into an unexpected enemy at 20 knots it takes a bit of time to slow down and for the sensors/sonar to work. I can slow down in a hurry by going to back emergency, I been on boats where this has been done and it makes big wakes, disturbances, and air bubbles. Anyone know if Im setting off signal flairs and laying out the welcome mat for the Russians doing this? With the new update I am still doing alright with subs but surface encounters are still giving me trouble so its hard to tell, I dont get cavitation warnings, anyone know? Thanks Jay

12-31-17, 11:29 AM	#2
THEBERBSTER Growing Old Disgracefully Join Date: Dec 2012 Location: Dibden Purlieu - Southampton Posts: 9,605 Downloads: 1123 Uploads: 0	A Warm Welcome To The Subsim Community > drhyed Subsim <> Make A Donation <> See The Benefits <> Support The Community __________________ LSH3-2015 <> TUTORIALS <> ALL YOU NEED TO KNOW <> ALL IN ONE PLACE SH4 <> TUTORIALS <> HOW TO DO IT <> INFORMATION <> DOWNLOAD LINKS SH5 <> TUTORIALS <> HOW TO DO IT <> INFORMATION <> DOWNLOAD LINKS Always Here To Help A Fellow 'Subber' \| Need An Answer to A Question Just Send Me A PM

12-31-17, 07:42 PM	#3
Killerfish Games Cold Waters Developer Join Date: Aug 2012 Posts: 274 Downloads: 0 Uploads: 0	You're not giving away yourself. You are rapidly decelerating so your flow noise and engine noise will decrease quickly. __________________ Visit Killerfish Games for more info and ongoing discussion.

01-01-18, 03:29 AM	#4
Capt.Hunt Loader Join Date: Nov 2017 Posts: 90 Downloads: 9 Uploads: 0	I'm sure one of our resident submariners could give us a definitive answer, but you'd think going all back emergency would make a heck of a racket. After all, the screw is only optimized to turn one way, and the pumps would probably shift to high speed.

01-01-18, 03:52 AM	#5
ET2SN ET2/SS Join Date: Oct 2017 Posts: 2,513 Downloads: 58 Uploads: 0	I guess it depends. Real world, its not like you're shifting gears from the helm. All you're doing is turning the dial on the announceator which makes the pointer move on a similar dial back in Maneuvering. Its up to the throttleman to see the new order and turn the "big wheel" to drive the screw, just like when you give a spoken order to "make turns for X knots". So, I guess you can assume that you have a sharp throttleman back aft who knows you want to slow down fast.

01-01-18, 10:19 AM	#6
drhyed Swabbie Join Date: Dec 2017 Posts: 9 Downloads: 12 Uploads: 0	In thinking about it more the screw is attached to a electric motor and with an electric motor you can use induction to instantly reverse the polarity, which then works like a giant brake on the motor at the expense of heat generation ( I think? going off of my very limited knowledge of how trains work and driving a Prius ) just flip the switch on the side of a ceiling fan when its spinning on high to see what Im referencing, now image if your ceiling fan blades were in water, consider how quickly they would slow down. Im sure with some testing at a place like the The Navy's Acoustic Research Detachment in Idaho they could work out a chart which got me down below 10 knots with the best risk vs reward for noise crated vs the disturbance I made in the water. Of course it would probably be contained in a chart with a million curves and lines for each 25 feet of depth and each 2 knots of speed I was going and require the use of a slide rule to decipher but thats part of reward of being a sub captain!