Andrew wrote:

> There is a useful YouTube site called "Whats going wrong with shipping"

That's "on" not "wrong"

> or something very similar that shows a lot of interesting data about
> this incident and others affecting shipping.

There's also this <https://keybridgeresponse2024.com>

Chris Green <cl@isbd.net> wrote:

> Still very, very little time to change course in one of those monsters.
>
> Stopping times and distances are huge, a quick search turned up this
> figure for the stopping distance of a not very big cargo ship:-
>
> Cargo ships loaded, displacement 28000 tonnes L 145 m
> 11-13 ship's length
> 9-11 minutes
>
> This is much smaller than the ship that hit the Baltimore bridge. Changes
> of direction will take a bit less time two to four minutes isn't enough to
> make a major change of direction.
>
So why did it veer so far off course so quickly? Or was it not on course
before the power failure?

--
braind

In message <mpro.sbcdt7006g1b9066w.me9@privacy.net>, at 02:07:55 on Wed,
3 Apr 2024, me9 <me9@privacy.net> remarked:
>Chris Green <cl@isbd.net> wrote:
>
>> Still very, very little time to change course in one of those monsters.
>>
>> Stopping times and distances are huge, a quick search turned up this
>> figure for the stopping distance of a not very big cargo ship:-
>>
>> Cargo ships loaded, displacement 28000 tonnes L 145 m
>> 11-13 ship's length
>> 9-11 minutes
>>
>> This is much smaller than the ship that hit the Baltimore bridge. Changes
>> of direction will take a bit less time two to four minutes isn't enough to
>> make a major change of direction.
>>
>So why did it veer so far off course so quickly? Or was it not on course
>before the power failure?

I heard one report that it was because they dropped an anchor on one
side, which then caused the ship to veer around. Perhaps they should
have dropped it on the other side?
--
Roland Perry

On 4/2/2024 9:07 PM, me9 wrote:
> Chris Green <cl@isbd.net> wrote:
>
>> Still very, very little time to change course in one of those monsters.
>>
>> Stopping times and distances are huge, a quick search turned up this
>> figure for the stopping distance of a not very big cargo ship:-
>>
>> Cargo ships loaded, displacement 28000 tonnes L 145 m
>> 11-13 ship's length
>> 9-11 minutes
>>
>> This is much smaller than the ship that hit the Baltimore bridge. Changes
>> of direction will take a bit less time two to four minutes isn't enough to
>> make a major change of direction.
>>
> So why did it veer so far off course so quickly? Or was it not on course
> before the power failure?
>

There is at least one youtube video, which does a good job of
explaining what happened.

There is an underwater channel, off to the side of the main
channel, and that's a "variable" in terms of pushing on the
ship as it went by. These are 50 foot deep shipping channels,
Y shaped, and the ship was passing that fork in the center,
when it moved to the side. The tide level could influence
the level of current flow in the channel.

The rudder is cut fully to one side, to act as a brake. The
ship is NOT steering straight forward during this. The pilot
dropped anchor, but the anchor chain visual appearance
gives no info. Can't tell whether the anchor was dropped
five miles back or only fifty feet from the resting point.

Ships that size would have more than one anchor. The description
suggests only one was dropped.

I don't really think the anchor is intended to stop a moving
100,000 ton load. It's more likely to be used to "hold position"
once vessel velocity is zero.

https://en.wikipedia.org/wiki/Anchor

Anchor porn

https://upload.wikimedia.org/wikipedia/commons/0/05/Anchor_types.jpg

Paul

me9 <me9@privacy.net> wrote:
> Chris Green <cl@isbd.net> wrote:
>
> > Still very, very little time to change course in one of those monsters.
> >
> > Stopping times and distances are huge, a quick search turned up this
> > figure for the stopping distance of a not very big cargo ship:-
> >
> > Cargo ships loaded, displacement 28000 tonnes L 145 m
> > 11-13 ship's length
> > 9-11 minutes
> >
> > This is much smaller than the ship that hit the Baltimore bridge. Changes
> > of direction will take a bit less time two to four minutes isn't enough to
> > make a major change of direction.
> >
> So why did it veer so far off course so quickly? Or was it not on course
> before the power failure?
>
That it was off course long before the power failure and collision is
what I was suggesting.

--
Chris Green
·

On 03/04/2024 09:37, Chris Green wrote:
> me9 <me9@privacy.net> wrote:
>> Chris Green <cl@isbd.net> wrote:
>>
>>> Still very, very little time to change course in one of those monsters.
>>>
>>> Stopping times and distances are huge, a quick search turned up this
>>> figure for the stopping distance of a not very big cargo ship:-
>>>
>>> Cargo ships loaded, displacement 28000 tonnes L 145 m
>>> 11-13 ship's length
>>> 9-11 minutes
>>>
>>> This is much smaller than the ship that hit the Baltimore bridge. Changes
>>> of direction will take a bit less time two to four minutes isn't enough to
>>> make a major change of direction.
>>>
>> So why did it veer so far off course so quickly? Or was it not on course
>> before the power failure?
>>
> That it was off course long before the power failure and collision is
> what I was suggesting.

Or it was steering a course to follow an underwater channel and power
failed just when it needed to make a turn to stay within the channel.

On 03/04/2024 11:53, SteveW wrote:
> On 03/04/2024 09:37, Chris Green wrote:
>> me9 <me9@privacy.net> wrote:
>>> Chris Green <cl@isbd.net> wrote:
>>>
>>>> Still very, very little time to change course in one of those monsters.
>>>>
>>>> Stopping times and distances are huge, a quick search turned up this
>>>> figure for the stopping distance of a not very big cargo ship:-
>>>>
>>>>      Cargo ships loaded, displacement 28000 tonnes L 145 m
>>>>      11-13 ship's length
>>>>      9-11 minutes
>>>>
>>>> This is much smaller than the ship that hit the Baltimore bridge.
>>>> Changes
>>>> of direction will take a bit less time two to four minutes isn't
>>>> enough to
>>>> make a major change of direction.
>>>>
>>> So why did it veer so far off course so quickly? Or was it not on course
>>> before the power failure?
>>>
>> That it was off course long before the power failure and collision is
>> what I was suggesting.
>
> Or it was steering a course to follow an underwater channel and power
> failed just when it needed to make a turn to stay within the channel.
>
Or was actually making a turn, and the rudder became useless when power
failed

--
Outside of a dog, a book is a man's best friend. Inside of a dog it's
too dark to read.

Groucho Marx

On 4/3/2024 7:22 AM, The Natural Philosopher wrote:
> On 03/04/2024 11:53, SteveW wrote:
>> On 03/04/2024 09:37, Chris Green wrote:
>>> me9 <me9@privacy.net> wrote:
>>>> Chris Green <cl@isbd.net> wrote:
>>>>
>>>>> Still very, very little time to change course in one of those monsters.
>>>>>
>>>>> Stopping times and distances are huge, a quick search turned up this
>>>>> figure for the stopping distance of a not very big cargo ship:-
>>>>>
>>>>>      Cargo ships loaded, displacement 28000 tonnes L 145 m
>>>>>      11-13 ship's length
>>>>>      9-11 minutes
>>>>>
>>>>> This is much smaller than the ship that hit the Baltimore bridge. Changes
>>>>> of direction will take a bit less time two to four minutes isn't enough to
>>>>> make a major change of direction.
>>>>>
>>>> So why did it veer so far off course so quickly? Or was it not on course
>>>> before the power failure?
>>>>
>>> That it was off course long before the power failure and collision is
>>> what I was suggesting.
>>
>> Or it was steering a course to follow an underwater channel and power failed just when it needed to make a turn to stay within the channel.
>>
> Or was actually making a turn, and the rudder became useless when power failed
>

This is a replay of the track.

"MV Dali Hitting Key Bridge in Baltimore - Track and Video Analysis"

https://youtu.be/N39w6aQFKSQ

That space between the pylons seems pretty small,
when a vessel can no longer steer.

Paul

On 4/2/2024 10:14 PM, Roland Perry wrote:
> In message <mpro.sbcdt7006g1b9066w.me9@privacy.net>, at 02:07:55 on Wed, 3 Apr 2024, me9 <me9@privacy.net> remarked:
>> Chris Green <cl@isbd.net> wrote:
>>
>>> Still very, very little time to change course in one of those monsters.
>>>
>>> Stopping times and distances are huge, a quick search turned up this
>>> figure for the stopping distance of a not very big cargo ship:-
>>>
>>>     Cargo ships loaded, displacement 28000 tonnes L 145 m
>>>     11-13 ship's length
>>>     9-11 minutes
>>>
>>> This is much smaller than the ship that hit the Baltimore bridge. Changes
>>> of direction will take a bit less time two to four minutes isn't enough to
>>> make a major change of direction.
>>>
>> So why did it veer so far off course so quickly? Or was it not on course
>> before the power failure?
>
> I heard one report that it was because they dropped an anchor on one side, which then caused the ship to veer around. Perhaps they should have dropped it on the other side?

The claim was, they not only dropped one anchor, they also
railed the rudder to one side, for usage as a brake. Which
of course, it's not all that much of a brake.

https://www.politifact.com/factchecks/2024/apr/02/facebook-posts/baltimore-bridge-collapse-federal-state-officials/

"The ship’s pilot ordered his crew to turn the Dali’s
rudder hard left and drop the ship’s left anchor, Diamond said."

"At 1:27 a.m., the Dali’s pilot ordered the left anchor to be dropped
and issued additional steering commands"

One thing you should notice is.

1) Ship is steering to the left of center.
2) Rudder is cut to steer the ship to the left.
3) Left anchor is dropped.

When the ship passes the 50 foot deep Y-shaped channel,
the ship steered to its right.

I think the pilot knows the water velocity
in the unused fork of the Y in the plot.
And one of the reasons the ship was traveling
at 9 instead of 6, was to compensate for the
expected sideways push. It was an attempt to maintain
rudder efficiency when the ship was still steering straight.

I don't think there have been any comments from the pilot.
The flight recorder will have most of the details captured.
The rudder setting at least, will be there.

I think additional anchors were dropped, when it came
to a stop. That's why the right anchor seemed so "limp".

Paul