Model Boat Mayhem

Mess Deck: General Section => Chit-Chat => Topic started by: Brian60 on February 10, 2015, 04:17:43 pm

Title: Anchor chains-Marking
Post by: Brian60 on February 10, 2015, 04:17:43 pm
Somebody was asking about this subject last week but I can't remember which topic it was in. I found this earlier today so it's going to be useful for everyone really.
MARKING THE ANCHOR CHAIN
For the safety of every ship, the ship's officers and the boatswain must know at all times the scope or how much anchor chain has been paid out. To make this information quickly available, a system of chain markings is used.
COLOR MARKINGS
21-13. The tools required for color marking an anchor chain are wire brush, paint brush, rags, and paint (red, white, blue, and yellow enamel paint).
  • 15 fathoms (1 shot). The detachable link IS painted red, and one link on each side is painted white.
  • 30 fathoms (2 shots). The detachable link is painted white, and two links on each side are painted white.
  • 45 fathoms (3 shots). The detachable link is painted blue, and three links on each side are painted white.
  • 60 fathoms (4 shots). The detachable link is painted red, and four links on each side are painted white.
  • 75 fathoms (5 shots). The detachable link is painted white, and five links on each side are painted white
Paint each link in the next to last shot yellow. The yellow alerts you that you are running out of chain. Paint each link in the last shot red. Note: 1 fathom = 6 feet. There are 15 fathoms (90 feet) in a shot of anchor chain. Note: This method is used through the entire marking procedure alternating red, white, and blue for detachable links as appropriate.
Title: Re: Anchor chains-Marking
Post by: senlac on February 11, 2015, 01:45:29 am
I haven't noticed this kind of marking but a slightly different one where all the detachable links are painted red.
Title: Re: Anchor chains-Marking
Post by: Nemo on February 11, 2015, 09:21:26 pm
Uh-oh!  'It wasn't me Sir'!!   %)

https://www.youtube.com/watch?v=b7pRfix_sNg
Title: Re: Anchor chains-Marking
Post by: derekwarner on February 11, 2015, 09:56:27 pm
That Officer @ 4:19 minutes with his hands in his pockets looked a little disinterested........lets blame him O0 ......

Dereliction of duty, failing to supervise subordinate ratings, failing to ensure the correct and safe manner in the use of the vessels equipment and machinary............

The list goes on & on <*<......do we hear the 'F' word used? :embarrassed: ....Derek
Title: Re: Anchor chains-Marking
Post by: Nemo on February 11, 2015, 10:21:51 pm
 .

Title: Re: Anchor chains-Marking
Post by: Bob K on February 11, 2015, 10:25:03 pm
Isn't the other end supposed to be secured to something ?
Title: Re: Anchor chains-Marking
Post by: carlmt on February 11, 2015, 11:25:24 pm
At the speed that was paying out, I doubt even if it was secured to Fort Knox it would have stayed that way!!!
 
Can you imagine the damage it would have caused if it WAS secured tight enough not to have gone AWOL?
Title: Re: Anchor chains-Marking
Post by: Mad Scientist on February 11, 2015, 11:48:21 pm
Yes, the anchor chain is supposed to be secured, but it was hard to tell from the video whether it was unsecured, or if there was some sort of 'fail-safe' system which let go to minimize the damage.
I would have expected to see more PPE being used: ear defenders, dust masks and safety goggles, at least. The noise and rust particles you get in an enclosed cable deck has to be heard and seen to be believed.
Ah well, at least that officer had his hands 'safe' in his pockets. >>:-( <*<

Tom
Title: Re: Anchor chains-Marking
Post by: Nemo on February 13, 2015, 08:43:34 pm
Isn't the other end supposed to be secured to something ?

Yes, in most vessels - including large ships. If you can build a large ship then you should be able to build in a secure method of securing the anchor chain before it disappears accidentally - as on this occasion. There may have been a braking system to slow down and secure this warships cable but it was clear that the sailors had slackened off the brake too much and were unable to control it before the cable went in the drink. Even on all my small yachts, I had a large eye-bolt with a massive backing-pad to ensure the strain would (hopefully) not tear a hole in the bulkhead. This diagram shows a typical ship layout - maybe the Yanks have different methods from others. I wonder how the RN does it? By the way - this bulkhead fastening is called a 'BITT' and the last link of an anchor cable is thus known as the 'bitter end', which is the origin of the common phrase.


 
Title: Re: Anchor chains-Marking
Post by: Nemo on February 13, 2015, 08:45:33 pm
Error. %)]
Title: Re: Anchor chains-Marking
Post by: Peter_s on February 13, 2015, 09:04:45 pm
Would they attempt a recovery of the lost gear?
Title: Re: Anchor chains-Marking
Post by: derekwarner on February 14, 2015, 04:30:12 am
 ;)     yes Peter......an anchor & chain on a BHP Fleet Operations 100,000 tonner 40 years ago had a replacement cost of $0.28M

During manufacture, every individual studded forged link is subject to ultrasonic NDT....prior being assembled into the next link in the chain...many links, many cables, many $

The anchor & chain set was lost from the Iron Somersby during a cyclone off Port Headland on our far west coast

Without two working windlass/anchors systems, the ship was out of Classification with Lloyds for insurance ...a very expensive scenario of anything happened  >>:-(.... Derek
Title: Re: Anchor chains-Marking
Post by: BarryM on February 14, 2015, 09:27:42 am
Isn't the other end supposed to be secured to something ?

It's happened again and once again my golden prose has disappeared down the electronic plughole and so I'll repeat the gist of it.

The chain was lost because, whatever the cause, it's weight took over and it ran away. Anchor chains are always run out under power/brake to maintain control unless it is a dire emergency and all control has been lost.
My guess is that the chain was 3" stud-link and 14 shots went overside. (1 shot = 15 fathoms) A shot of 3" weighs about 8,000lb and thus the chain that went out was ca. 50 tons plus the anchor. That sort of weight running at 3' - 4' per second is going to generate a helluva lot of kinetic energy. You may have a big fat padeye in the chain locker to secure the bitter end of the chain to but if you expect it to resist the force then you are going to have to beef up the plate to which the padeye is secured and then the scantlings of the structural members that support that and so on and so on. Thus the reason for fitting a weak link between the chain and the padeye. In extremis, the weak link parts and the chain goes overside but the locker structural integrity remains intact.

 I am unable to check it out for the moment but a weak link may well be a Classification Society requirement although, of course, warships are not built to Class but have their own standards.

I'm not sure what type of vessel the above drawing refers to but the idea of going into a locker and removing the split pin and thus the retaining pin from the chain "in emergency" is definitely one to file under "After you Claude; no after you Cecil".

By the by, I always understood 'bitts' to be deck furniture used for mooring.

Barry M
Title: Re: Anchor chains-Marking
Post by: Bob K on February 14, 2015, 09:53:45 am
I had read your response yesterday, but always useful to have on record to read again. Thanks for re-posting.

For anything other than short replies I tend to write postings in Word, including IMG URL picture links. That way if anything glitches I can re copy / paste into Mayhem.
Title: Re: Anchor chains-Marking
Post by: NFMike on February 14, 2015, 10:32:30 am
It's broadly similar to runaway trains or heavy lorries. If the speed is allowed to get past a critical value the gravity and inertia exceed the power of the brakes.
Game over.
Title: Re: Anchor chains-Marking
Post by: pugwash on February 14, 2015, 01:14:46 pm
For those of you who have not been involved in anchoring be it a large ship or a yacht,
the anchor is dropped in x metres of water and then slowly paid out so the required amount
of chain/cable is lying on the bottom, but the chain is paid out as the ship SLOWLY is
making sternway.  If the ship goes astern at several knots, the capstan brake is let out but
will be unable to stop the chain at that speed and will probably burn out the breaking system.
I think it is likely that the bridge of that ship bears some responsibility of what was on the
video.
For info an anchor does not hold a ship in position - it is the weight of the chain along the seabed
which does the job - the anchor just hold the end of the chain so that it should not drag.(in theory)
Geoff
Title: Re: Anchor chains-Marking
Post by: Bob K on February 14, 2015, 01:38:52 pm
For info an anchor does not hold a ship in position - it is the weight of the chain along the seabed
which does the job - the anchor just hold the end of the chain so that it should not drag.(in theory)
Geoff

Interesting.  I had always imagined that a short length of chain along the seabed pulled up the anchor flute/s so they dug in, a bit like the hook on the end of an elastic luggage bungee cord.  So what are the flukes for then, if it is merely weight of chain that prevents drifting?
Title: Re: Anchor chains-Marking
Post by: pugwash on February 14, 2015, 02:34:38 pm
Bob, perhaps I did a poor job of describing it but the anchor flukes dig in when the ship
has sternway either from the engines or wind/tide (As you always try to anchor head to wind)
but the weight of chain keeps the anchor and ship in position - if you do not have sufficient
chain on the bottom the weight of the ship snubbing at the anchor will tend to lift the anchor stock
and so make the anchor drag or break free of the bottom.  There is a formula for type of bottom,
depth type of anchor whether is is attached to cable or chain or as in a lot of yachts chain then onto
rope. If it is done correctly as the tide turns the ship should swing on the end of the chain that is on the
seabed and not the anchor. Hope that makes sense
Geoff