About an help for a MsC about Emergency Anchoring


#41

It’s it really acceptable to have a container ship with enough horsepower to go 24 kts if it can’t use full throttle in a confined harbor?

That’s a truly ridiculous question, especially since it was explained earlier.

It’s in seamanship manuals, you should gave been aware of it. People can’t tell you about everything you should know.

In a well protected harbor anchorage you’ll likely not experience the jerking motions necessary to part the chain. Luckily, that’s also where it’s most important that you hold fast. In offshore anchorages where the sea state could shock load the chain you need be prepared to drag on a shorter scope or just get underway.


#42

You don’t want the anchor to hold in an emergency because it will part. You want it to drag on a short stay and slow the vessel down so you don’t hit anything.


#43

Nobody is claiming that dropping anchors is applicable to every situation in an emergency where a ship needs to be stopped or brought under control.

And 50 tons is not nothing, roughly about a 4000 or 5000 hp tug pulling at full power, might be useful in some cases.


#44

Anchors should never be used outside designated areas. The following letter reposted from a year ago contains a cautionary tale reminding us all to be extra careful with those anchors.

Dear Sir,

It is with regret, and in haste, that I write this letter to you - regret that such a small misunderstanding could lead to the following circumstances, and haste in order that you may get this report before you form your own preconceived opinion from reports which may appear in the press. I am sure the media will tend to over dramatize the affair.
We had just picked up the Pilot as darkness fell, and our apprentice was on the bridge wing. He was replacing a “G” flag with an “H” flag and was having difficulty with a fouled halyard. I proceeded to show him how to clear the flag and told him to “Let go.” The lad, although willing, is not too bright, and I was obliged to repeat the order, but in a sharper tone. At this moment, the Third Officer appeared from the chart room, having plotted the vessel’s progress up the channel, and thinking I was referring to the anchor, repeated the order “Let Go!” to the Chief Officer on the fo’c’sle head. The port anchor, having been cleared away, but not walked out, was promptly let go. The effect of letting go the anchor while the vessel was proceeding at full harbor speed proved too much for the windlass brake, and the entire length of chain was pulled out and lost over the side. I fear the damage to the chain locker may be extensive.
The braking effect of the port anchor naturally caused the vessel to sheer in that direction, directly towards a swing bridge that spans a tributary to the river up which we were proceeding. The swing bridge operator showed great presence of mind by opening the bridge to my vessel. Unfortunately, he did not think first to stop the vehicular traffic, the result being that the bridge partly opened, depositing a Volkswagen, two cyclists, and a cattle truck on the foredeck. My ship’s company are at present rounding up the contents of the latter which, I would say from the loud squealing, are pigs. In his efforts to stop the progress of the vessel, the Chief Officer then dropped the starboard anchor, too late to be of any practical use as it fell on the swing bridge operator’s control cabin.
After the port anchor was let go, and the vessel started to sheer, I gave a double ring Full Astern on the engine room telegraph, and I personally rang the engine room to order maximum astern revolutions. I was politely informed that the sea temperature was 53 degrees, and was asked if there was a film tonight. My reply would not add constructively to this report.
Up to now, I have confined my report to the forward end of my vessel; back aft they were having their own problems. At the moment the port anchor was let go, the Second Officer was supervising the making fast of the after tug, and was lowering the wire to the tug. The sudden braking effect of the port anchor caused the tug to run under the stern just at the moment when the propeller was answering my double ring Full Astern. The prompt action of the Second Officer in securing the inboard end of the wire delayed the sinking of the tug by some minutes, thereby allowing the safe abandoning of the vessel.
It is strange, but at the very same moment of the letting go of the port anchor, there was a power loss ashore; the fact that we had passed over a Cable Area at that time suggests that we may have touched something on the river bed. It is perhaps lucky that the high tension cables brought down by our foremast were not actually live, possibly having been replaced by the underwater cable. Owing to the shore blackout, it is impossible to say when the pylon fell.
What never fails to amaze me are the actions and behavior of foreigners. The Pilot, for example, is at this moment huddled in the corner of my day cabin alternately crooning to himself and crying, after having consumed the entire contents of a bottle of my best Gin in a time worthy of inclusion in the Guinness Book of World Records.
The tug captain, on the other hand, reacted violently, and had to be forcibly restrained by my chief steward who has him handcuffed and strapped to a gurney in the ship’s hospital, where he is telling me to do impossible things with my ship and person.
I enclose the names and addresses of the drivers and insurance companies of the vehicles deposited on my foredeck which the Chief Officer collected after his somewhat hurried evacuation of the fo’c’sle. These particulars will enable you to claim for the damage that they did to the railings around the hatchway of number 1 hold. I am closing this preliminary report, for I am finding it difficult to concentrate because of the squealing pigs, the loud police sirens and flashing lights. It is sad to reflect that, had the apprentice realized that there is no need to fly a pilot flag after dark, none of this would have happened.
For my Weekly Accountability Report, I will assign the following casualty numbers; T/750101 to T/750199 inclusive.

Yours Sincerely,
Hugh B. Sharp, Master


#45

From the table, taking one of the container-ships fitted with a 11 tonnes anchor, it uses 95mm chain. The mass of a shackle of cable is 5.4 tonnes only. The holding power from the cables are much smaller.


#46

It could be understood that none of my arguments ask for an immediate stop of a ship or successful application on everything. However, the ship will slow down and eventually stop hopefully before hit the thing. Just want to learn more about possible limits.

The topic is about emergency anchoring of ships initiated by a merchant navy ship-master. It is very likely be operated in well protected harbour. Offshore industry is so specialized, outsider like me simply will not dare to think about facing their problems.

I am sorry. It does not look like an authorized answer. It looks like more a personal view in a discussion.

On the one hand,

on the other hand,

Okay, I will try to find one… seamanship manuals. I really did not come across with anything about that limit.


#47

I think that I am not saying 50 tonnes is nothing. It is no match to the huge momentum of the ship even at very slow speed. At that slow speed, it is not necessary so desperate to carry out such a risky operation.


#48

We are talking about using an item in a manner that it was not intended to be used on most modern ships and therefore it was not built or designed for the loads your considering.

And fatalities can occur, have occurred in the past, and will, unfortunately, continue to occur when people try to outsmart themselves. It’s like the investigation into the sinking of the two Maersk Supply vessels on the way to the breakers. The risk assessment was full of wishful thinking.

I like the ideas of using it to slow the vessel and help with turns, but if it’s that critical to be able to stop a large vessel at five knots they should be using escort tugs in that area.

You know, use the right tool for the job.


#49

My understanding of emergency anchoring is that attempting to drag or dredge an anchor at something like 15 knots over the bottom is not advisable.

If you lose the plant and are still making a decent amount of way through the water, shift your rudder back and forth and if you have a bow thruster, counter that with the rudder till you can get the speed down to something safer to attempt releasing the anchor. Release just enough scope to basically “bounce” the anchor along the bottom, trying to reduce speed but not dig in.

If you’ve lost steering at that kind of speed, you are most likely going to go aground before you can even get the anchor to run.

If you are moving less than 5 knots approaching a berth, by all means attempt to dredge the anchor to avoid an allision.

This is all subjective to the conditions, the size of the vessel, the quality of the anchoring gear, etc. Trying to put a metric or trying to quantify this is too variable in my opinion. Good luck with your thesis though.


#50

This thead has was interesting: Anchors - Poor Man’s Tugboat


#51

It depends on the circumstances of course but a large ship moving too fast can be brought under control using the anchors. I was on the bow of the Spirit (244 meters) coming into Hong Kong many years ago.

I don’t know what was happening in the wheel house but from the bow it seemed we were going too fast and were about to take out a container crane or two. The captain ordered the stbd anchor dropped. I ordered the bosn to open the brake, let a couple shots run out and set the brake. The chain was maybe 30 or 40 degrees from horizontal.

We spun around right quick, the turn is what takes the speed off, not the anchor. The anchor down moves the pivot point way forward.

This ship is the one the was the subject of the thread:
Pasha to use laid-up ship to deliver water to Puerto Rico


#52

It could be a mismatch of expectation and reality about harbour tugs. The 50-100 tonnes of bollard pull is very small when comparing to the momentum of a moving ship at that speed. And very often, the bitts and bollards on board are not able to withstand that amount of pulls. After all, emergency anchoring is about anchoring in emergency, in areas, something somewhere somewhat unexpected.

Exactly… it may be one of the areas that Antonio is looking into. Making an angle of 30 degrees across a stream could be making as much as half of the pressure that could be generated at right angle. That is what rudder circling about, I guess. The small rudder, the anchor drag in this case, may not reduce a ship’s speed much. The ship’s hull may.

Antonio, please consider sending us a copy of your thesis when it is completed.


#53

I have when sailing as second mate been on the forecastle of a ULCC in the early 1970’s been there when we lost an anchor due to our speed over the ground being higher than the command appreciated. The brake linings started to overheat and we attempted to cool the brake with a fire hose. When this failed to have any effect and with the bitter end of the cable fast approaching I ordered the abandonment of the forecastle. I thought I was fairly fast on my feet but some of the crew could have given an Olympic track star a run for their money.
The cable caused extensive damage to fixtures and fittings before disappearing overboard and we were all glad we were somewhere else.
The second anchor was lost on a supply vessel where I was mate. We were anchored in relatively deep water and was much less dramatic. The cable parting just above the anchor shackle.
I have used the anchor as an aid to manoeuvring by dredging it berthing at wharf to turn head to wind and make a stern board to the wharf in a single screw coastal vessel equipped with a bow thruster in strong wind conditions.
The strength of anchoring equipment and cable of a 4000 tonne coastal vessel is far greater proportionly than that of ships of larger tonnage.
I was always taught that never run aground with an anchor in the pipe.


#54

On the Hurtigruten (Coastal Express) ships in the Norwegian coast using an anchor to turn on approach, or to pull off from a wharf, especially in bad weather, used to be common practise, like here:


MS Nordstjernen (built 1956) leaving Aalesund .

I was kind of surprised watching one of the newer ships (with thrusters galore) actually setting an anchor when coming alongside in Aalesund in a stiff Northerly breeze.


#55

Old habits die hard.


#56

Yes, with 34 ports each way and 11 days/roundtrip, year around in any weather, they do get a lot of experience in ship handling.
Many of the ports with limited turning space and the requirement to always be port side alongside doesn’t make it any easier.

Besides, there are a lot more windage in the newer ships:


#57

Not necessarily, at least in my experience. Once you pay out a shot in the water you will slow significantly, even if you have a bell on the engine, in fact on some ships you may need to increase revolutions. Four shots will stop you and any more than that you won’t be able to generate headway and run the risk of parting the chain. This is why I always lower the anchor on the windlass while dredging. It prevents the chain from running and allows the precise adjustment to make the operation effective.


#58

Yes, no doubt in many cases the anchor can be used to take the speed off.


#59

I’m new here. I’ve been lurking for a few years but decided to sign up as there are times I have questions and times I feel I can contribute. I’m an active unlimited pilot and have had some experience in this topic so feel I can contribute some here…I’ll just throw a few things out based on my experiences:

Even 1 shot will slow a ship…I frequently anchor on a flood tide and pay out 1.5 shots and drive her to the spot I want to anchor on dead slow. Often I’ll have to bump to slow ahead because that 1.5 shots will stop the ship. Occasionally I’ve used half if they ended up with 2 shots out. Always walk it out on the windlass if you are dredging…or you run the risk of not being able to stop it.

Pivot point moves basically to the fwd perpendicular…very handy for precise manuevering.

I believe anchors will drag before gear parts assuming gear is sized appropriately for the vessel and in decent condition.

I have let go anchors in emergency situations. The most memorable (read…scary) was a 600ft bulker with 34ft draft with following current. I was on sea speed making about 12kts and had an engine failure due to low sulfur fuel seizing a fuel pump (the low sulfur B.S. is another discussion). I let go an anchor due to a 30 degree turn and rocks 1 mile ahead…it was really my only option. By that time the ship had slowed to 10 kts due to no engine. It was 0400 and vis was about 50 ft due to fog. I purposely told the bosun to let go 1 shot and hold on…he got it stopped at 11 shots. It stopped the ship. Lessons learned/confirmed by my experiences:
*as soon as that anchor drops the brake needs to be going on, don’t say 4 or 5 shots then put the brake on as it’ll be too late,
*danger is extremely high for crew on the bow, I still hear the screaming
*make sure you have the water to do this so you don’t run over the anchor and breach the hull. In this instance I had 10ft ukc. I had a slight swing to port so I dropped the port anchor.
*time is of the essence, crew needs to be stationed on the bow with anchors on stby for all channelling
cycling the rudder does help burn speed if you’re able
*don’t expect people to perform in an emergency situation, they may or they may not. On this instance the helmsman, mate and captain all froze…the bosun is the only one who acted.