Milano Bridge allides with gantry crane in Busan today

“pour the coals to her for a clean getaway”

… to where? They appear to be in a closed basin. I agree that dropping an anchor might cause a sheer but, holy shit, I would have been praying for a sheer to starboard. Drop the starboard anchor just 1-2 shots and a sheer to starboard is exactly what you want. Sheering to port where the other ships are would be highly unlikely with the starboard anchor.

And if you only had one anchor? Still,way past time to do that. Those cats up forward were ducking and running.

As a pilot, I gave anchor instructions/recommendations to the captain directly. He was responsible for carrying them out. You can’t micromanage in a situation like that. Ideally the pilot would have asked the captain to have the crew stand by the anchors when he boarded. That’s mandatory in the US in pilot waters. When the pilot saw that the situation was getting dangerous he should ask the captain to have the crew stand by to drop both anchors but wait for the order. Then when the time comes the pilot says drop the anchor (either or both). The captain is free to do whatever he wants, but as a pilot in charge I want my recommendations and orders recorded on the voice data recorder.

There should be no shouting on the bridge. The biggest problem with anchor orders is the whistle blowing the danger signal. It can deafen the sailors on the bow and cause them too misunderstand. Keep that in mind when you give your orders. Only blow the whistle when you are not trying to give an order.

Agree, but moot here. That did not happen in this instance .

And 6 knots coming alongside the pier is not a controlled approach That’s why I suspect either mechanical problems or more difficult to explain, a complete breakdown in communications.

5 posts were split to a new topic: Barbers Cut / Houston Ship Canal

This thread is a little disorganized because the first posts which were based on the videos alone are being replied to based of the chartlet and narrative which was posted later.

As far as using the anchor; I don’t know why they didn’t. .

Like this?

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The two choices faced could be characterized as using speed to get away or slowing down and getting the ship under better control.

If they had chosen to slow down and get the ship under control with the tug assist then perhaps using the anchors would have been a good option. But it doesn’t look as if that was what they were trying to do.

Anchors wouldn’t have been my first choice either. With speed up around 8-9 knots approaching the turn into the basin (due to mechanical failure or whatever) I’d have been making that turn with the bow tug alongside facing forward and backing full. That would have made the turn tighter and kept them from setting down while slowing the ship down at the same time. The stern tug would have been in line backing hard too. But you can’t just do that and hope for the best. You have to make yourself do a loop of observe–orient–decide–act over and over again. Maybe the next time through the loop you see she is making the turn ok but still has too much speed so then you drop an anchor.

But I wasn’t there. Usually I wouldn’t second guess a pilot but in this case it’s almost like the pilot had a heart attack or something and wasn’t part of the picture.

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I agree on that approach. Most of the time I liked that bow tug up close.

The following is from the ‘Ship Maneuvering Technical Reference’.

Speed Control page 28, which is highly applicable in this case.

Incidents of failing to control a ship’s speed while entering harbour, with the vessel consequently colliding with the pier causing major damage to the pier, shore cranes, and the vessel itself, never cease.

Approximately 70% of incidents of damage to harbour facilities involve damage to piers and fenders, however most are due to mistakes in operation of the vessel.

Such mistakes in confined harbours with limited area available for maneuvering are due to the following:

(1) Inability to accurately determine the effects of external forces such as wind and tides.

(2) Mistakes in speed control and turning of the vessel while using engines and tugs.

IMG_5805

According to this table the Milano Bridge, which has a DWT of 146931 tons, needed 3 - 4 tugs. The engine power is sufficient: 38490 kW.

Also of interest is the item “Preventing Damage to Harbour Facilities” on pages 40 - 43. On page 49 it says:

It is necessary for the captain to plan the procedure for entry and exit in advance.

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That’s a good find.

My thinking here is this is more of a planning error than an error of execution. There are several factors here which may have put this shiphandling problem outside the pilots experience and seat of the pants intuition.

From my experience at least pilots in Pusan don’t do a real master/pilot exchange. Just sign the paper and get on with it.

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I counted only two tugs. If so that should have been indeed 3 or 4 with this kind of ship, lightly loaded and propeller partly out if the water. Normally speaking here the tug’s captain would use his ship transverse as a drogue chute to decelerate the ship. I don’t know how much bollard pull they have while going astern as can be seen on the videos.

How much power is being transferred given the propeller immersion?

Shown are submergence depths of / 0.0, 0.5, and 1.0. Here, h is the submergence depth from the free surface to the propeller shaft center and R is the radius of the propeller. With h/R 0.5 the propeller blade is half out of the water. We don’t know how much blade of the Milano Bridge is out of the water and that makes it hard to estimate the loss of thrust, but there is still a lot left.

It is interesting to read that a surface-piercing propeller is one of the most efficient propulsion systems for high-speed vessels. They can use a larger propeller size because it is not limited by the minimum blade tip clearance from the hull or the maximum vessel draft. Moreover, they can avoid cavitation damage because the propeller operates under ventilated conditions by drawing air from the free surface.

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Some good research here. I think the speed given is the maximum at landing on the wharf which is about a quarter of a knot. It sounds a bit too high for anything over 100,000 tonnes. I remember at Rotterdam back in the 70’s they had big dials on the Quay which gave the approach speed of the bow and stern as metres and decimal parts of metres per second.
The major ports in NZ equip the pilot with an electronic device that gives approach speeds and distance off independently of ship’s equipment and the display can be moved around the bridge wherever the pilot wants.

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I don’t know how to read that table. Presumably T is thrust and Q is torque. I don’t know what the n is.

If this table is applicable we could assume the Milano Bridge prop is about 1/4 out of the water what results does that give?

Google tells me that n is efficiency which is: Efficiency = 100% - Slip.

In this case it looks like its the third column divided by the forth column. ( 8th row: 0.259/0.314 = 0.824)

I think it is safe to interpolate this value which is half of the half blade distance, thus in between 1 and 0.789 which amounts to about 0.89 of thrust meaning that 89% of the full thrust is available at that moment.

The efficiency, generally indicated with the nabla sign η, is the quotient of thrust and torque.

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I was thinking that on the Milano the Bridge the blade was likely more than 1/4 out of the water so 1/4 would be h/R = 0.5.

From h/R = 1.0 at 2 rps thrust drops off from 0.944 to 0.789 which is -20.6%.