cruise ships

You dummy...a lighthouse is FOR attracting ships for the sirens to eat..

It was your armed forces, so maybe they really were stupid - those who don't know history are condemned to repeat it

-- Bill Sloman, Nijmegen

John Larkin schrieb:

Hello,

a sonar giving the depth right under the ship would not help to see a rock needle miles away. If the cruise ship runs full speed, they can take only a wide curve.

Bye

Dave Platt schrieb:

Hello,

if they fly high to save fuel, the margin between the lowest possible speed and the maximum air speed is very small. If they are slower, the lift of the wings is to small. If they are faster, they are too close to the sonic barrier.

Bye

I would have thought that a cruise ship could have afforded side-scan sonar - I worked on a phased array ultrasonic imaging scanner for medical diagnostics 1976-1979 and under-sea imaging was a whole lot easier (and already popular, even then - fishing boats used it to find fish!).

-- Bill Sloman, Nijmegen

Consider that once they saw their path collided with an object. it was likely too late to make an adjustment that would be successful, since the ship weighs hundreds of tons.

They likely were trying to steer clear, but far too late.

My guess would be that trying to steer clear was the proximate cause of the grounding.

A possible scenario: Bridge is uncomfortable with their track and feels that they may standing into danger and decide to come right. A course change is ordered as they are approaching the Isole le Scole, a rocky islet SE of Giglio harbor, off the port bow. The rudder swings right but that action pushes the stern to the left where it brushes up against submerged rocks. That's a big-ass ship and the stern is a couple of hundred meters aft of the bridge

It looks like they almost made it clear. A little less rudder and they might have missed the rocks. Be interesting to hear whether there was a helmsman or whether the course change was just punched into a voyage management system (autopilot) which just used its standard algorithm to determine the rudder angle.

This morning, the Capt. is saying that they were given/using the wrong maps.

Bill Sloman schrieb:

Hello,

but the front-scan sonar needed here should work over a distance of several miles, the medical ultrasonic scanner only over a distance of about 10 centimeters. Think about the radar equation, 10000 times the distance means 10^16 times more pulse power.

Bye

So you are saying that the people who conceived and implemented GPS are stupid?

John

...and they didn't notice that they'd taken the wrong turn at Albequirky? The captain is dead, in any case.

f.

If it hasn't got some kind of anti-spoofing capability, it isn't going to be much use during armed conflict.

I've got no idea whether it has or not - but it would be odd if it didn't. And why did you snip my reference to the "battle of the beams" without marking the snip? It's a rhetorical question ...

-- Bill Sloman, Nijmegen

Side scan sonar doesn't have to scan directly to either side - you can orient the fan beam so that it does scan ahead.

-- Bill Sloman, Nijmegen

The attentuation in the body is rather higher than in sea water, and the frequencies required to resolve rocks rather lower than the 2MHz we were using. Front scan sonar has been a practical proposition for a long time.

-- Bill Sloman, Nijmegen

Here in the US, state laws generally REQUIRE a local, licensed, harbor pilot to bring the ship in. Presumably, they are extremely familiar with the harbor and sea lanes, and therefore, safer than the boat's captain. I wonder if those same sort of regulations apply overseas.

My brother (who works on a cruise ship in Europe) says some of these "captains" over there are "cowboys". The rumor du juor is the captain was showing off for one his buddies on shore. I heard that 3rd hand, at least, so no intent to start an unsubstantiated rumor. Would make sense though. A boat that big, and that expensive, has GOT to have many countermeasures against "accidents" like this! No (rational) inventor would ever pump money into a project like that without those protections.

-mpm

I'd have thought that a call to the FCC should sort that out.

It seems to have had all mod cons and a black box so the GPS track and recordings of the sensors and bridge conversations should shed a lot of light on proceedings. They are reporting it as human error here now.

It shows an unauthorised deviation in the route by the captain.

Chances are that even if the forward looking sonar beam had seen an obstruction it would already be too late to turn such a massive ship when travelling at full cruise speed. Supertankers have similar problems with manouverability and turning circles.

It is also possible that in trying to avoid a collision they tore a gash along the side of the ship in a similar way to the sinking of the Titanic. Both ships might well have survived a head on into the obstruction which would disfigure the bow and rearrange the furniture mightily but the remaining watertight bulkheads ought to hold.

A long tear down one side letting in water in is a worst case scenario.

Regards, Martin Brown

The FCC don't appear interested in that sort of thing.

I figure it is a manpower issue.

Oh Well.

--Winston

Military ships do have different requirements and design goals. Most US carriers and cruisers are steam driven. Still, many smaller (destroyer / frigate) class men-of-war have compound turbine engines.

?-)