Model Boat Mayhem

Mess Deck: General Section => Full Scale Ships => Topic started by: BarryM on December 18, 2008, 02:10:24 pm

Title: When Anchors Fail - Rev.1.
Post by: BarryM on December 18, 2008, 02:10:24 pm
Liberian-registered 'Fedra' grounded on Europa Point, Gibraltar, in October. Note both anchors out. Five crew were taken off by Spanish SAR helo which then had to make an emergency landing after water ingress to the engines. The rest of the crew were very lucky to be taken off in a basket suspended by a mobile crane taken to the Point.

Now if these pics will post you can supply your own caption for the last one........

Barry M
Title: Re: When Anchors Fail - Rev.1.
Post by: craftysod on December 18, 2008, 02:17:04 pm
Copper is probably thinking "i can issue 2 parking tickets now"
Title: Re: When Anchors Fail - Rev.1.
Post by: dougal99 on December 18, 2008, 05:21:01 pm
Probably grounded on all the rubbish the Gibraltarians dump into the sea at that point.  >>:-(

Green what's green?????
Title: Re: When Anchors Fail - Rev.1.
Post by: BarryM on December 18, 2008, 05:53:19 pm
Aw c'mon - with whisky at 4 per bottle it's my favourite place.  %%

Barry M
Title: Re: When Anchors Fail - Rev.1.
Post by: tobyker on December 18, 2008, 07:05:27 pm
The word "awesome" is much overused but......
Title: Re: When Anchors Fail - Rev.1.
Post by: BarryM on December 18, 2008, 07:16:32 pm
Reportedly the salvage of the Fedra is providing a local glut of scrap metal as she followed the Ocean Flame which sunk about a half-mile off Europa Point earlier in the year. The salvage/scrapping of the latter vessel has already filled the local Steptoes.

Barry M
Title: Re: When Anchors Fail - Rev.1.
Post by: Sea Commander on December 18, 2008, 07:21:27 pm

 Brilliant series of pictures !!

 Thanks for sharing them with us all.

 The power of the sea is mighty,

 I remember going out from Yarmouth and a storm hitting the boat whilst out. Nothing like this,  but boy was I frightened.   I can understand Mariners being superstitious.

 Thanks & Regards

Mark
Title: Re: When Anchors Fail - Rev.1.
Post by: tigertiger on December 19, 2008, 01:09:37 am
A possbile caption for Picture08

Can I have two cornettos and a cup of tea with two sugars, please.
Title: Re: When Anchors Fail - Rev.1.
Post by: Martin [Admin] on December 19, 2008, 06:26:26 am

http://uk.youtube.com/watch?v=lG-6Z-1GuuA

Title: Re: When Anchors Fail - Rev.1.
Post by: nhp651 on December 19, 2008, 09:14:00 am
Caption
"Silly sod!
didn't  she see the lighthouse, it's big enough.
B****y women drivers!!!" {-) {-)
Title: Re: When Anchors Fail - Rev.1.
Post by: derekwarner on December 19, 2008, 10:06:20 am
Hi all....did the anchors really fail?????????????????????????...I think not! :police:

One of the issues with hydraulic tension/mooring winches is

1) the vessel may have has two anchors out
2) these would have been locked in mechanical stoppers on deck & with the windlass mechanical brake band tensioned

When the inclement weather appears...a series of events occur

3) start the hydraulic system
5) release the mechanical windlass brakes
6) attempt to haul in the anchors

This is where the  scenario begins..........

7) the windage against the vessel hull is greater than the hauling capacity of the winches
8) the manual directional control valve is returned to neutral...all ports blocked center
9) the continued force of the windage against the vessel means the vessel moves, but the anchors are locked & hence the hydraulic winch internal rotating vane elements [400 Bar synthetic] are distroyed

The first 100,000 tonner....1966 Japanese IHI built Sig Silver/Chelsea Bridge/Iron Sirius  had IHI Norwinch winches built under licence & had cross line relief valves set to 350 Bar which negated the problem noted at point 9)

20 years later BHP Steel ordered four new 100,000 ton bulk ships for the iron ore trade ....but as a cost cutting measure the windlass cross line relief valves were not installed

So after a few cyclones off Port Hedland....& ships loosing an anchor or so & hence loosing Lloyds classification to sail. >>:-( ..we had the task of retro fitting the 100 kg blocks of cross line relief valves .....

So did the anchors drag?....I thought the water off Gibraltar was rocky.....surely they would not have placed the vessel with out an emergency engine start up time?......Derek

Title: Re: When Anchors Fail - Rev.1.
Post by: BarryM on December 19, 2008, 10:47:22 am
Derek,

Forget the theorising. Simply put, the main engine failed while the vessel was underway. Both anchors were put out as a last resort to prevent wreck. They were unlikely to hold in the circumstances but anything was worth a try. Didn't matter whether the windlass was hydraulic, steam or powered by a crew with capstan bars.

Barry M
Title: Re: When Anchors Fail - Rev.1.
Post by: derekwarner on December 19, 2008, 11:19:09 am
Hi Barry... I certainly was not attempting to theorise on the demise of this vessel...but just to offer qualified comment on what can happen under similar or dis-similar circumstances


I note in the second .jpg.... both anchor chain appear to be in tension......these chains could be up to 400 kg/metre however this does not relate to any potential for anchor dragging.....also the same .jpg confirms the vessel is de-balasted & hence very high in the water....& so high windage  etc....Derek
Title: Re: When Anchors Fail - Rev.1.
Post by: BarryM on December 19, 2008, 05:52:15 pm
Chain is probably standard marine grade 3" at about 3.5 tonne/shot. They are bound to be trailing away from the vessel as it crabs on the Point.

Barry M
Title: Re: When Anchors Fail - Rev.1.
Post by: farrow on December 29, 2008, 10:49:00 pm
The area where she anchored is known not to be the best holding ground, years ago when I was in the St Maragarets, we frequently had to go and repair the cables to NATO's secret underwater noise listening hydrophone just off the point. As ships frequently dragged thier anchors and cut the cable, also looking at the photos she had all her chain out and it was under some strain looking at high and straight it was out off the water.
Title: Re: When Anchors Fail - Rev.1.
Post by: trainspotter on December 30, 2008, 03:53:59 pm
Does anyone know what has happened to the ship since? She was also on the cover of the last Ships Monthly which gave the detail as to what initially happened to her.
Title: Re: When Anchors Fail - Rev.1.
Post by: BarryM on December 30, 2008, 04:30:27 pm
Salvage by Titan in hand. Aft-end (superstructure & engine room) to Gib for scrap. Remainder to Algeciras for possible repair with new aft-end grafted on.

Barry M
Title: Re: When Anchors Fail - Rev.1.
Post by: Bryan Young on December 31, 2008, 06:28:20 pm
In an odd sort of way I was intrigued by the way the ship seemed to find a "nesting" berth within the cliffs. Snuggled in quite neatly.
The water off Europa Point is pretty deep and so I would imagine that the anchor cables were let out to the max. (11 shackles?).
Many ships have gone down in the Straits and very few were discovered. The main reason being the constant pushing and pulling of the continents (over the millenia, not in one human lifespan) that has created a really nasty and jagged sea-bed that even large ships can get lost in, never to be found except by accident or really dilligent searching. Normally no-body bothers to look. Especially if the wreck has been washed over ino the deep side. But next time the Med dries out bits and pieces may be found. Don't hold your breath. BY.
Title: Re: When Anchors Fail - Rev.1.
Post by: cdsc123 on December 31, 2008, 08:18:03 pm
 :o
Title: Re: When Anchors Fail - Rev.1.
Post by: TCC on January 18, 2009, 12:00:00 am
The area where she anchored is known not to be the best holding ground, years ago when I was in the St Maragarets, we frequently had to go and repair the cables to NATO's secret underwater noise listening hydrophone just off the point. As ships frequently dragged thier anchors and cut the cable, also looking at the photos she had all her chain out and it was under some strain looking at high and straight it was out off the water.

Can you confirm a question for me? When at anchor under a big anchor with a fair length of cable (chain) out, that it is the weight of the cable laid along the seabed that helps stop the ship moving, and not the grabbing power of the anchor alone, as such?

or...

is there a technique of anchoring where: Say the ship is in water of 10 fms. It plays out 50 fms of cable with a 5 ton anchor at the end. The cable weights 5 tons per 10 fms of chain. So now the chip is anchored by a 5 tn achor and 25tns of chain.

The clever bit is they only need a windlass equal to hauling 10 tns, not the 30 tns that is out, as it is never pulling on the complete cable as 2/3rds of it is lain upon the bed, the ship jst slowly steams up it's anchor line taking in the cable as it goes. I've simplified the above a lot... and I'm talking principles, not excact max cable depths or windlass abilities.

Is that how the big ships work? Or is that 1 technique of many... of the big ship anchoring techniques?
Title: Re: When Anchors Fail - Rev.1.
Post by: derekwarner on January 18, 2009, 01:05:37 am
mmmmmmmmmmm...Hi all......lets go back to first principals

1) irrespective of the mass [weight] of the anchor or chain....the windlass is simply providing a hauling moment which moves the mass [displacement] of the vessel toward the anchor on the seabed

2) if the.....windage ...tide or current [acting against the vessel mass] exceeds the windlass pull....then the result is that the anchor + chain being hauled in is the result of two elements

3) it is only when the vessel is directly above the anchor....that the required effort to haul in the anchor & chain must exceed the weight of the sum of elements.....

Pretty simple...... %%....derek
Title: Re: When Anchors Fail - Rev.1.
Post by: Bryan Young on January 18, 2009, 06:47:12 pm
The general wisdom (and I have no reason to disagree) is that the anchor of a ship will hold the cable and the weight of the cable holds the ship. But that only applies to a ship. I have no idea how oil rigs and so on are moored. BY.
Title: Re: When Anchors Fail - Rev.1.
Post by: Eddy Matthews on January 18, 2009, 06:58:46 pm
I did notice that the part of the hull that failed was at the crew quarters...... The front end (the bit with the expensive cargo onboard) remained intact. Makes you wonder what the ship designers/owners consider most valuable?  {:-{ :}

Eddy
Title: Re: When Anchors Fail - Rev.1.
Post by: Ghost in the shell on January 18, 2009, 07:14:54 pm
didnt the darbyshire class freighters have a flaw at that same point?
Title: Re: When Anchors Fail - Rev.1.
Post by: BarryM on January 18, 2009, 08:48:59 pm
The general wisdom (and I have no reason to disagree) is that the anchor of a ship will hold the cable and the weight of the cable holds the ship. But that only applies to a ship. I have no idea how oil rigs and so on are moored. BY.

The same principal applies except that rigs will usually have eight or twelve moorings deployed: each being about a half-mile long, laid to a very precise pattern and with all tensions continuously monitored to ensure the correct catenary is being maintained - highly important if pipelines are being crossed. Either all-chain (3" - 4") or wire plus chain in the thrash zone, is used. Deployment and recovery is via anchor-handling vessels.

Barry M
Title: Re: When Anchors Fail - Rev.1.
Post by: amdaylight on January 19, 2009, 02:14:38 pm
What you want is the anchor to lay flat on the bottom so the flukes can bite in to the bottom, when I had my full size sail boat the first 25' were chain and the rest was rope. If I was worried about the anchorage I would do the same thing that they used to do in the time of sail with a large ship and that is to put a second anchor at the end of the chain who's whole job was to make sure that the chain laid flat on the bottom and the pull on the main anchor was kept parallel to the bottom. You get in to problems when the anchor line or chain starts to put an upward pull on the anchor and the flukes come out of the bottom.

Andre
over yonder in Portland Oregon
Title: Re: When Anchors Fail - Rev.1.
Post by: Bryan Young on January 20, 2009, 08:01:52 pm
That is a good answer for when ships had anchor "cables" made of rope. A second anchor was needed to hold the first.
It is also a good time to wonder why a socking great studded chain is called a "cable". And also to wonder why some ropes are "cable-laid" and others are not. Something to do with twisting I think.  But then there is a dichotomy. You can anchor with a "cable", but you lay it out in "shackles". "How much cable is there out?" ...."5 shackles...(.or whatever".). A cable is a finite length. A "shackle" is a finite length.They are not the same. Work it out for yourself!
Title: Re: When Anchors Fail - Rev.1.
Post by: Colin Bishop on January 20, 2009, 08:26:24 pm
The line you are referring to is called Octoplait when used on yachts. It doesn't twist and will not get tangled up when flaked down. Lovely stuff. So nice that I kept mine when I sold the boat!

Colin
Title: Re: When Anchors Fail - Rev.1.
Post by: amdaylight on January 20, 2009, 08:41:45 pm
That is a good answer for when ships had anchor "cables" made of rope. A second anchor was needed to hold the first.
It is also a good time to wonder why a socking great studded chain is called a "cable". And also to wonder why some ropes are "cable-laid" and others are not. Something to do with twisting I think.  But then there is a dichotomy. You can anchor with a "cable", but you lay it out in "shackles". "How much cable is there out?" ...."5 shackles...(.or whatever".). A cable is a finite length. A "shackle" is a finite length.They are not the same. Work it out for yourself!

As Tevye sang in "Fiddler on the Roof" TRADITION  O0 O0

Andre
over yonder in Portland Oregon
Title: Re: When Anchors Fail - Rev.1.
Post by: BarryM on January 20, 2009, 10:47:46 pm
What you want is the anchor to lay flat on the bottom so the flukes can bite in to the bottom, when I had my full size sail boat the first 25' were chain and the rest was rope. If I was worried about the anchorage I would do the same thing that they used to do in the time of sail with a large ship and that is to put a second anchor at the end of the chain who's whole job was to make sure that the chain laid flat on the bottom and the pull on the main anchor was kept parallel to the bottom. You get in to problems when the anchor line or chain starts to put an upward pull on the anchor and the flukes come out of the bottom.

Andre
over yonder in Portland Oregon

Use of a second anchor  is common in offshore operations in poor holding ground; commonly known as a 'piggy-back anchor'.

Barry M
Title: Re: When Anchors Fail - Rev.1.
Post by: 6705russell on March 12, 2009, 12:51:06 pm
The remains of the Fedra as of yesterday.... some of the hull is in port.
Title: Re: When Anchors Fail - Rev.1.
Post by: nhp651 on March 12, 2009, 12:59:33 pm
NEXT stop ,Vauxhall for  a new Corsa or two.lol
the power of the sea. <:(