https://youtu.be/vWneBzYW9Ig

USS Fitzgerald Memorial Service

These are excerpts from the June 27, 2017 Yokosuka, Japan memorial service for seven sailors who died aboard USS Fitzgerald on June 17, 2017. Speaking are Adm. Scott Swift, commander U.S. Pacific Fleet and Vice Adm. Joseph Aucoin, commander U.S. 7th Fleet.


https://news.usni.org/2017/06/...-died-uss-fitzgerald

quote:

Originally posted by sdy:
How fast can a DDG 51 class come to a stop from full speed?
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20 seconds

video at:

https://www.youtube.com/watch?v=IuXOr4Z9RDI

another article at:

http://foxtrotalpha.jalopnik.c...-the-burk-1681758438

If they're feathered, each screw acts as a speed brake, a maneuver known as a "crash-back." That allows the 9,000-ton destroyer to go from around 36mph to a dead stop in about 20 seconds.

Yeah, but that kinds of stop would throw everyone out of their bunks and vibrate the entire ship something crazy

quote:

Originally posted by jimmy123x:
[QUOTE]

A freighter captain told me it takes 9 miles to stop a freighter under a normal stop. 6 miles in an emergency stop and you break $250k worth of stuff.

I also think it takes a while to make a decent turn when at cruise speed.

Quite honestly, I think the freighter captains story is bs, about using lights to signal them. Your first course of action would be to call them on the vhf radio. But, impossible to prove or disprove using lights.

Whistle signals generally are not used at distances over a .5-1 mile as they generally won't be heard inside a wheelhouse over other noise. Usually they're used in harbors and such.

Reminds me of a freighter running right up the arse of the USCGC Hollyhock here a few years ago. It wrinkled it up bad, but nothing like that destroyer.

in the videos a DDG 51 does a crash back w civilians on board

I roughly timed it and it took longer than 20 sec. Someone at the end of the video seems to say it wasn't a full crash back.

They did say the deck vibrated

quote:

Originally posted by jimmy123x:

quote:

Originally posted by sdy:
How fast can a DDG 51 class come to a stop from full speed?
.
.
.
.
.
.
.
.
.
20 seconds

video at:

https://www.youtube.com/watch?v=IuXOr4Z9RDI

another article at:

http://foxtrotalpha.jalopnik.c...-the-burk-1681758438

If they're feathered, each screw acts as a speed brake, a maneuver known as a "crash-back." That allows the 9,000-ton destroyer to go from around 36mph to a dead stop in about 20 seconds.

Yeah, but that kinds of stop would throw everyone out of their bunks and vibrate the entire ship something crazy

It sounds a lot more dramatic than it really is. I did them many times on an FFG - it stops inside of its own length, 440' +/-. You'd do them for trials of one sort or another, or even just to give the families a smile during a Tiger Cruise (a day-trip for the crew's kin). Nothing ever got damaged.

30 knots to nothing in 440' is pretty sedate when you actually do it. Lots of vibration in the aft part of the ship; you didn't feel it further forward. A big spume of froth at the fantail. No real G forces that you can feel, either standing or sitting.

15 seconds of that would have saved the lives of the guys on Fitzgerald.

When the dust settles on this investigation, they're going to find that a whole long list of people dropped the ball simultaneously, and if just ONE of them had done their job properly, the collision would not have occurred.

Been there, seen it.

quote:

Originally posted by whanson_wi:


It sounds a lot more dramatic than it really is. I did them many times on an FFG - it stops inside of its own length, 440' +/-. You'd do them for trials of one sort or another, or even just to give the families a smile during a Tiger Cruise (a day-trip for the crew's kin). Nothing ever got damaged.

30 knots to nothing in 440' is pretty sedate when you actually do it. Lots of vibration in the aft part of the ship; you didn't feel it further forward. A big spume of froth at the fantail. No real G forces that you can feel, either standing or sitting.

I bet it is nothing compared to 30 knots to zero in 50' when you stick the pointy end into a large tanker you didn't see.

why would a crash back throw people out of their bunks ?

35 mph to 0 in 20 seconds

You can stop your car from 35 mph to 0 in about 4 seconds

think about driving your car 35 mph and taking 20 sec to stop. doesn't sound too bad

quote:

Originally posted by sdy:
why would a crash back throw people out of their bunks ?

35 mph to 0 in 20 seconds

You can stop your car from 35 mph to 0 in about 4 seconds

think about driving your car 35 mph and taking 20 sec to stop. doesn't sound too bad

None of the ships I was on had a prop that changed pitch...so that would make a huge difference. Mostly it's not the stopping, but the damaging that occurs to the reduction gears and loose gear shifting about the interior of the vessel and smashing into stuff...a person can grab onto fixed items and would have no problem with an "All Back" order from Flank speed...

quote:

Originally posted by sdy:
why would a crash back throw people out of their bunks ?

35 mph to 0 in 20 seconds

You can stop your car from 35 mph to 0 in about 4 seconds

think about driving your car 35 mph and taking 20 sec to stop. doesn't sound too bad

Because if you're not expecting it,such as someone sleeping, it would be like having someone sleeping on the hood of your car and doing a normal stop from 35 mph, they're going to go flying off of the hood or at least rolling fast.......loose items all over the ship are going to fall over and hit walls and stuff. A ship isn't like a car, it's angle is going to change and pitch a lot when this sudden stop happens......the props will cavitate a lot and send vibration through most of the ship also...... The ships also stresses all of it's running gear, engine and gear mounts and things of that nature.

quote:

Originally posted by jimmy123x:

quote:

Originally posted by sdy:
why would a crash back throw people out of their bunks ?

35 mph to 0 in 20 seconds

You can stop your car from 35 mph to 0 in about 4 seconds

think about driving your car 35 mph and taking 20 sec to stop. doesn't sound too bad

Because if you're not expecting it,such as someone sleeping, it would be like having someone sleeping on the hood of your car and doing a normal stop from 35 mph, they're going to go flying off of the hood or at least rolling fast.......loose items all over the ship are going to fall over and hit walls and stuff. A ship isn't like a car, it's angle is going to change and pitch a lot when this sudden stop happens......the props will cavitate a lot and send vibration through most of the ship also...... The ships also stresses all of it's running gear, engine and gear mounts and things of that nature.

Physics. A car stopping from 35 mph is nowhere NEAR the MASS of a ship stopping from 35 mph. Think of the difference in energy to stop the momentum of the two. Plus with rubber on the road, you have friction to slow you down. Slowing down in a liquid involves physics I can't even make up...would have to call Sheldon Cooper on that.

quote:

Originally posted by erj_pilot:

quote:

Originally posted by jimmy123x:

quote:

Originally posted by sdy:
why would a crash back throw people out of their bunks ?

35 mph to 0 in 20 seconds

You can stop your car from 35 mph to 0 in about 4 seconds

think about driving your car 35 mph and taking 20 sec to stop. doesn't sound too bad

Because if you're not expecting it,such as someone sleeping, it would be like having someone sleeping on the hood of your car and doing a normal stop from 35 mph, they're going to go flying off of the hood or at least rolling fast.......loose items all over the ship are going to fall over and hit walls and stuff. A ship isn't like a car, it's angle is going to change and pitch a lot when this sudden stop happens......the props will cavitate a lot and send vibration through most of the ship also...... The ships also stresses all of it's running gear, engine and gear mounts and things of that nature.

Physics. A car stopping from 35 mph is nowhere NEAR the MASS of a ship stopping from 35 mph. Think of the difference in energy to stop the momentum of the two. Plus with rubber on the road, you have friction to slow you down. Slowing down in a liquid involves physics I can't even make up...would have to call Sheldon Cooper on that.

Why not? Jimmy makes up stuff all the time, as here.

You just lack imagination!

How come your head snaps backwards when someone punches you?

When a ship is pushed sideways suddenly the fluid resistance of compressing water changes toward being solid, thus the damaged structures on both ships instead of just swapping paint.

17 knots to to a deflected course at 5 knots in milliseconds? <--- Just a wild ass example, I don't know what change of direction or speed would or did happen.
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quote:

Originally posted by springnr:
How come your head snaps backwards when someone punches you?

You might be on to something. Isn't it supposed to be an opposite reaction?

35 mph to 0 in 20 sec is not a sudden stop.

watch the video. Do you see the civilians falling down ?

It is a smooth gradual slow down on a DDG 51

This isn't smashing your foot on the brake. It is controlled and gradual.

The collision w the Crystal generated much higher rates of velocity change over a very brief period of time. That is what threw people out of their bunks.

some numbers:

under constant deceleration, from 35 mph to 0 in 20 sec would mean the ship traveled 513 feet.

The deceleration would be 2.6 ft/sec^2

The same numbers apply if you stopped your car from 35 to 0 in 20 sec at constant deceleration

gravity acceleration is 32 ft/sec^2

This message has been edited. Last edited by: sdy,

quote:

Originally posted by JALLEN:

Why not? Jimmy makes up stuff all the time, as here.

You owe me a keyboard


And he seems to be the subject matter specialist of all things that float and plumbing!

It may not seem bad on deck but I have watched 65,000hp of turbines bouncing like they weren't bolted down in the engine room.

It's a tad more exciting down there!

popping deck plate screws are fun.

Here is some more informed speculation about this incident that may have some interest.

Why did the USS Fitzgerald crash?

A note about DDG 51 Flight III. (a little OT)

https://news.usni.org/2017/06/...eigh-burke-destroyer

Huntington Ingalls Industries won an award to build the first of a new configuration of Arleigh Burke guided missile destroyers, according to a Tuesday Pentagon contract announcement.

HII’s Mississippi Ingalls Shipbuilding is now set to construct the first Flight III DDG that will be built around an air search radar that promises to be 30 times more powerful that the current crop of AN/SPY-1D(V) and built from the start for complex ballistic missile defense missions.

The award of the first Flight III -– named for Marine Capt. Jack H. Lucas — comes as the service has been in negotiations for more than a year with HII and Bath over the engineering change proposals to modify the current Flight IIA design to accommodate the Raytheon-built AN/SPY-6 radar with the necessary power, cooling and an adequate margin for growth for future systems.

The radar will allow the guided missile destroyers to better detect and track traditional air warfare threats like cruise missiles and aircraft as well as ballistic missiles simultaneously, the Navy has said.

Navy needs to take a long hard look at close in surface tracking and navigation after this collision

In addition to the SPY-6, the changes to the design will increase the power available on the ship by replacing three Rolls Royce 3-megawatt generators on the Flight IIA ships with Rolls Royce’s 4-megawatt generator in the same footprint on the ship.

The electrical grid on the ship will also be upgraded from the 450-volt configuration to a 4,160-volt grid, which will lead to additional design changes.

The ship is the fifth and last HII ship in a ten-hull multiyear destroyer deal crafted in 2013 between HII and Burke builder General Dynamics Bath Iron Works. At the time of the award, the price per hull came to $660 million for HII and $700 million for BIW. The cost for the hulls did not include so-called government-furnished equipment like radars or combat weapon systems which bring the cost of the destroyers to the government at more than $1 billion.

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DDG 62 is a Flight I ship

After so many days, Marine Traffic does not allow you to run track history for a vessel. The number of days depends on your level of subscription.

I expect my number of days will expire long before the Navy publicizes the DDG 62 track (if they ever do).

So I built a table that lists the information for some of the data points and numbered a track plot to map to the list.

Ignore the symbols of other ships in the track plot. Those ships were not from the time of the collision.