The problem is with steering. The rudder on a ship this big is going to be wall of steel several stories tall with gears as big as car.
Warships have several independent backup steering options reducing finally to a worm gear at the top of the shaft with a winch handle big enough to put a gang of men on it. But ships like this will have none of that. They will have a small wheel or joystick on the bridge and if power goes out the rudder will definitely stay in the last commanded position until power is restored. Even if they had auxiliary steering they would not have the crew to man those positions.
This ship would have alternate diesel power plants called "mules" (think APUs on aircraft). It's possible that when the lights came back on that was because they got a mule started.
But really if we don't want accidents like this to happen the ship should have redundancy. A 10,000 TEU container ship is one of the largest and heaviest moving structures ever created by man. Why is it acceptable that it is driven by exactly one engine powering one screw in front of one rudder?
By the way a ship this big with only one screw is very difficult to maneuver at slow speeds. They pretty much have to be going at least 14-15knots to have any rudder authority.
> But really if we don't want accidents like this to happen the ship should have redundancy. A 10,000 TEU container ship is one of the largest and heaviest moving structures ever created by man. Why is it acceptable that it is driven by exactly one engine powering one screw in front of one rudder?
Perhaps because we have a whole lot of them going and a very low frequency of events like this.
Maybe there's some lighter weight interventions we could do that would further halve the risk of something like this happening that are less costly than fully redundant engine and drive.
They're supposed to have emergency steering gear. Why didn't it work? Maybe ships should have an auxiliary genset running while near land.
Do we need kindergartens to be safe? How many dead kids is too many? /s
Seriously, in England it is a legal requirement to have redundant brakes on a freaking bicycle. A dude that hit a grandma with a bicycle due to 1 non-functional brake went to prison. But a giant container ship needs nothing?
What is the cost of fixing this bridge and + lost lifetime earning of all the people who dies + compensation to their families? Is that really cheaper than installing batteries plus electric motor?
Now imagine this ship would hit a bridge in daytime, when it’s clogged with traffic?
Cost/benefit analyses are just a fact of life. I see your point, but without really considering the question we don't know what the proper response is. It is not obvious to me that we need to mandate backup power systems, there are an awful lot of ships entering ports around the world each day and very few bridge collapses.
The problem is that the bridge collapses that do happen are just catastrophic. The economic impact alone will be massive for Baltimore. But will the responsible parties pay out that damage in full? Unlikely.
Cost-benefit analyses aren't designed to evaluate the total risk a business venture presents to everyone who could possibly be involved; they're designed to evaluate the risk posed by a problem that will launch lawsuits that will play out in courts for years, if not decades. Meanwhile, some injured parties settle for pennies on the dollar, laws change, and in the absolute worst-case scenario, major shareholders draw down their positions in the corporate venture that caused the problem. The world keeps on spinning, and just maybe some regulatory agency will pay attention to the report issued by the likes of the NTSB and USCG.
The process does not adequately protect the public.
Regulations are written in blood, because trying to make everything safe pre-emptively is impossible economically for a number of reasons. Primarily being, you can’t (usually) realistically force people to spend the money on something that isn’t clearly an actual problem.
And that fundamentally means until someone ‘bleeds’/a big enough disaster happens, some things won’t get fixed.
See the triangle shirt waist factory for an example of what it took to be able to force people to pay for certain kinds of fixes.
Since folks aren’t currently burning down the NTSB’s offices or the like, it also seems like your opinion that the public is not currently adequately protected isn’t a majority one?
The only way we’ll ever hit zero accidents is if we are all dead, it’s impossible to do anything without some risk.
I have lived in two different cities where no kindergarten age children have died getting hit by cars outside of their school.
Last year I saw a child fall off a raised garden bed at his school, hit his head, and leave in an ambulance. I never found out what happened as I was just visiting that small town.
Children die at or going to/from kindergarten a few times a year I bet in the US.
And this bridge being down will shutdown the port and reroute all automobile traffic that used to travel across it for months and the bridge itself will require design rebuilding, all of which will be extremely costly economically.
Biden has said that the Federal government will pay to rebuild the bridge, in order to get it done quickly.
But presumably they will ultimately seek reimbursement from the Dali’s insurers. As will the Port of Baltimore and anyone else who has suffered damages.
> What is the cost of fixing this bridge and + lost lifetime earning of all the people who dies + compensation to their families? Is that really cheaper than installing batteries plus electric motor?
I don't mean to contribute to this already-too-charged discussion any more than to say that the answer to this question is not as obvious as you think it is. If anything, I would bet that the former is less expensive than the latter, and I say that with immense sadness. Does that make sense?
It’s a legal requirement to have brakes on both wheels of your bicycle. That’s not the same thing as redundancy. Braking performance is significantly reduced if you can only brake on one wheel, so both brakes need to be functional to stop quickly and safely.
And the dude went to prison because he hit and killed a grandma while riding with reckless disregard for the safety of pedestrians. The brake thing didn’t help, but it was a side story.
On pavement, when the front brake performs well and is operated near optimal power, the back tire will not have traction. The back brake is entirely redundant in that case.
> ”Redundancy doesn't necessitate the redundant option being identical to the first.“
Yes. In fact, in a redundant system, using different designs or technology is often an advantage, so that a failure mode that affects one system is unlikely to affect the other.
But if something is redundant, it is “able to be omitted without loss of function”. Front and back brakes on a bike are not there for redundancy. They are components of the same braking system: without both in service, they don't work as well.
Or to put it another way, the front brake isn’t there as a spare in case the back brake fails. It’s there because without brakes on both wheels, you can’t stop quickly in an emergency.
> Front and back brakes on a bike are not there for redundancy. They are components of the same braking system: without both in service, they don't work as well.
Bikes are very different from cars due to the short wheelbase vs high center of gravity.
At moderate or fast speeds maxim deceleration occurs when the front tire applies enough force to lift the rear tires off the pavement thus removing the impact of the rear tires. Below maximum acceleration you could use the rear break but it doesn't do anything applying the front break slightly harder would do.
At sufficiently low speeds the rear tire can help, but it's really there for redundancy as even acting alone it doesn't work very well.
This only applies in ideal conditions (eg: dry tarmac). Where there is less surface friction (wet or icy surface, dirt or gravel trails, etc) you're going to quickly hit the limits of the tire's traction, so will need both brakes if you want to stop in the shortest possible distance.
Wet roads, cold ice, and dirt still provide enough friction to send you over your handlebars at speed. They just increase the maximum speed rear tires provide any benefit. Near its melding point ice isn’t going to provide enough friction for rear breaks to matter.
So sure there’s a minimal benefit in some very specific conditions, but no they are there for redundancy.
In reality, the rear brake contributes nothing (apart from redundancy in case of front brake failure) to being able to stop quickly in an emergency. The quickest stop is achieved by using the front brake as strongly as possible while bracing oneself to avoid going over the bars, which if done correctly, will mean the rear wheel will have next to no contact with the ground. That means locking the rear wheel with the rear brake will contribute nothing to stopping.
Conspiracy... some adversary is waiting for opportunities during unfavorable/aberrant conditions and triggering simple failures at impossibly inopportune times. Without any redundancy, conditions it looks like a freak accident. It would be interesting if you could come up with a likelihood for each conditions to have overlapped temporally. If someone comes to the conclusion that its possible to create the triggered failures it would be prudent to forbid sailing in conditions that might lead to these supposed "fly under the radar attacks".
> Maybe there's some lighter weight interventions we could do that would further halve the risk of something like this happening that are less costly than fully redundant engine and drive.
Redundancy doesn't inherently have to cost a lot more. For example, if you have three engines driving three props, they can each be 1/3 as large, and not necessarily weigh much more if at all. But then if you lose one, you lose 1/3 power rather than experiencing total loss of control.
> Redundancy doesn't inherently have to cost a lot more. For example, if you have three engines driving three props, they can each be 1/3 as large, and not necessarily weigh much more if at all.
Yah, from aviation everyone moved to twins because tri-jets and four engine jets were too expensive in comparison. Things don't scale up or down perfectly; in practice you end up with more maintenance.
But it seems like here they lost steering, so maybe there's something better we can do to keep steering more of the time (the cutover to emergency steering gear isn't instantaneous or perfect).
Planes use two engines because they can land with one and smaller jet engines are about as complicated as larger ones. Ships have different constraints. For example, a lower output diesel engine could have fewer cylinders and correspondingly lower maintenance costs.
but two engine jets can fly on one engine for a while, however a one engine boat this big is an uncontrolled juggernaut when it has some speed and no engine because it doesn't have any redundancy.
> but two engine jets can fly on one engine for a while
Not just for a while. They must be able to do so indefinitely, until you run out of fuel. Of course, you are going to want to get it back on the ground long before that happens.
Emergency steering gear is required on every commercial vessel and is regularly tested. We will have to wait for the investigation to see what actually happened.
Warships have several independent backup steering options reducing finally to a worm gear at the top of the shaft with a winch handle big enough to put a gang of men on it. But ships like this will have none of that. They will have a small wheel or joystick on the bridge and if power goes out the rudder will definitely stay in the last commanded position until power is restored. Even if they had auxiliary steering they would not have the crew to man those positions.
This ship would have alternate diesel power plants called "mules" (think APUs on aircraft). It's possible that when the lights came back on that was because they got a mule started.
But really if we don't want accidents like this to happen the ship should have redundancy. A 10,000 TEU container ship is one of the largest and heaviest moving structures ever created by man. Why is it acceptable that it is driven by exactly one engine powering one screw in front of one rudder?
By the way a ship this big with only one screw is very difficult to maneuver at slow speeds. They pretty much have to be going at least 14-15knots to have any rudder authority.