Magnetic Compass & Ore Carrying - Johnny

Harvatt
28th August 2011, 15:55
From Harvatt

Hi Johnny, nice to see a memo from you.
Subject to Maritime or Insurance Rulings, your answer is right, it is yes and in order to do it the ship would need to turn in full circles. Cargo shifting - this would be a case of " how long is a piece of string "
I am now retired and a little rusty, but I remember before Gyro was to be found in most vessels and before Decca and Sat Nav etc., a vessel coming from Japan To Immingham U.K. was using the Sun and Stars and having to follow other ships. Another ship placed a Lifeboat Compass in a neutral spot on a stool and managed to steer, using that. his Steering Compass was frozen to the bulkhead.
I personally - to prove a point to a master, swung a ship and placed some 20 magnets in and around the Binnacle just to free the compass. It was impossible of course to adjust it, all I could suggest was that he had the ship " wiped "
It depands generally upon whether the Ore was loaded or discharged by magnetic grab. The after effects were not so bad if it was'nt.
Hope this helps a bit.

Harvatt ( Terry )

Nick Balls
28th August 2011, 16:14
What is all this about!!!
We used to carry iron ore all the time and with a well kept compass record book and regular azimuths after loading never had any problem!! Yes it can have some big effects but then so can many other types of cargo. For example pipe carriers can see similar large effects.
Apart from very regular compass record keeping we also used to undertake our own ships 'swings' (between the 2 yearly compass adjusters official one) simply by sailing around in a circle and noting the heading differences between a fixed point (star)
In a similar way in very bad weather where use of a azimuth ring is impossible the foremast can be used by placing a low altitude star on a precise heading in alinement to the mast. Occasionally done on small vessels in high latitudes in extreme weather. I was always amazed by the accurate of such 'rough and ready' measures. But at least you knew what was going on! These days magnetic compasses are generally of poor quality.
The compass record book is still of huge importance and if not well kept and frequently used is a sure indication of some bad watchkeeping practices.

China hand
28th August 2011, 18:20
Lord, Nick; If only you could have time to hear the excuses I heard in my last years with "qualified" mates on why they couldn't, or didn't need to take a compass error and note it. One of the best was a radar bearing on a star, coupled with a GPS pos, was absolutely perfect. A radar bearing on a thrice copulating star for expletive deleted sake! Ho Hum.(Sad)

borderreiver
28th August 2011, 18:50
Always get my officers checking all compasses. This starts on the berth taking the brg of the jetty against chart. then again in locks and leading lights. then every watch by all means. Even found giro to be out by a few degrees at times.
I had Captain Compass at John Cass. Great teacher and wrote a book on the marine compass.

Nick Balls
28th August 2011, 19:05
China Hand,
I know what its like! I only gave up at sea in 2008 and was always involved in helping train people. Having seen a few (near misses) regarding gyro's and compass repeaters I always made sure these simple procedures of checking compasses was adhered to.
I also always taught cadets not to get to carried away with the theory side , having heard many a youth mutter about 'getting it wrong' because the answer gave a 5 deg gyro error (for example) This taught them the difference between a single calculation and a whole series and I made sure they put it in the book anyway, even if it was 'wrong'
Unfortunately towards the end of my career I saw several very senior people who were unable to even take a simple error and never took the simple precaution of using leading lights as a basic check.

borderreiver
Good to see that some still take it seriously

Tom Condren
28th August 2011, 19:37
This is a similar to the Iron Ore Carrier thread. The academics seem to have taken over the asylum.

John Cassels
28th August 2011, 20:28
From Harvatt

Hi Johnny, nice to see a memo from you.
Subject to Maritime or Insurance Rulings, your answer is right, it is yes and in order to do it the ship would need to turn in full circles. Cargo shifting - this would be a case of " how long is a piece of string "
I am now retired and a little rusty, but I remember before Gyro was to be found in most vessels and before Decca and Sat Nav etc., a vessel coming from Japan To Immingham U.K. was using the Sun and Stars and having to follow other ships. Another ship placed a Lifeboat Compass in a neutral spot on a stool and managed to steer, using that. his Steering Compass was frozen to the bulkhead.
I personally - to prove a point to a master, swung a ship and placed some 20 magnets in and around the Binnacle just to free the compass. It was impossible of course to adjust it, all I could suggest was that he had the ship " wiped "
It depands generally upon whether the Ore was loaded or discharged by magnetic grab. The after effects were not so bad if it was'nt.
Hope this helps a bit.

Harvatt ( Terry )

Ore discharged by magnetic grab ?? - this has to be a wind up .

Nick Balls
28th August 2011, 22:10
Taking compass errors........hardly academic! just plain ordinary common sense. AND common practice.

borderreiver
29th August 2011, 08:35
Taking compass errors........hardly academic! just plain ordinary common sense. AND common practice.

our eastern block crew only can use gps. Sextants and compass error not in there brain . Just sit in the pilot chair waiting for the gps buzzer to go to alter course no basic checking positions.

Tom Condren
29th August 2011, 08:44
Be careful when you 'knock' your Eastern bloc colleagues. It would not appear that SEXTANTS are in your brain either. Have you ever used one?

Tony Crompton
29th August 2011, 08:45
our eastern block crew only can use gps. Sextons and compass error not in there brain . Just sit in the pilot chair waiting for the gps buzzer to go to alter course no basic checking positions.

Glad we did not need or use sextons on British ships also.!!!

Nick Balls
29th August 2011, 10:57
Sailed with some very fine Polish seafarers who's training and knowledge is first class.
An amusing misunderstanding shown here between 'Sextants' and 'Compass errors' Should I be worried about all general competence levels these days?

sparkie2182
29th August 2011, 12:18
"a radar bearing on a star"

Terrific stuff.

:)

lakercapt
29th August 2011, 13:01
On A Roberstsons boat we had a general cargo from Antwerp to Lisbon. The deck cargo was railway lines.
Going down the Schelde we knew that the compasses were way out and not just a few degrees. On some courses it as as much as 45 degrees.
Thank goodness for Decca navigator as it was nearly overcast all the way and only in the Bay of Biscay were we able to get compass errors. Good job too as the Decca signal in that area was not that good.
Heaved a big sigh of relief when we berthed i Lisbon

Tom Condren
29th August 2011, 13:11
Should I be worried about all general competence levels these days?

YES!!

China hand
29th August 2011, 18:17
"a radar bearing on a star"

Terrific stuff.

:)

Sounds even better in Romanian(Ouch)

China hand
29th August 2011, 18:22
Sailed with some very fine Polish seafarers who's training and knowledge is first class.
An amusing misunderstanding shown here between 'Sextants' and 'Compass errors' Should I be worried about all general competence levels these days?

Many years ago, at anchor somewhere lovely, I showed a very keen Philipino 3rd Mate how to fix the ship with horizontal sextant angles. I have never forgotten the look on his face when he plotted that position, or his comment " Sir, this is like magic". He had a ticket, had never even heard of what I showed him. 199ty something.(Sad)

borderreiver
29th August 2011, 19:06
I did the same to my Philpino and they loved it next thing all the ABs were at at each anchorage. Great guys