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Ships Magnetic Compasses

42K views 123 replies 50 participants last post by  slick 
#1 · (Edited)
I am a new member to S.N. so forgive me if I lose my way a bit ! but I was
trained as a ship`s magnetic compass and nautical instrument maker,
completing my training with my M.O.T. cert. of competency as Compass
Adjuster. Leaving this specific trade many years ago and now totally retired
I am not a little conerned that almost nothing is published on these instruments and very little on the internet. This equipment was generally
hand made and thus highly skilled work. Do any members feel as I do that
it is a subject that should not be allowed to die out. I am of course referring
to the Real Equipment and not the mass produced ` equipment ` seen at times today .

Harvatt
 
#6 ·
I beleive that the marine magnetic compass was one of the most beautiful instruments ever made. For how many years or centuries was man's direction dependent on the magnet? When I travel I always have a small compass with me & I also incorporate them into my pocket sundials. About 8 years ago I saw a Beale's deviascope in an antique/junk shop in Newport Pembs for about £120 & I still rue the day that I did not purchase it.

Really nice to have someone on board who can actually manufacture one.

Welcome on board Harvatt.
Tony
 
#7 ·
Thankyou Tony for your welcome - yes I agree you did miss a snip, or rather treasure with your Beale`s Deviascope, having made repaired and tested so many of these years ago. I remember the work that went into them. There was always one of these in each School of Navigation, and used for examination purposes as well as training. I would like to think that a lot of this type of Marine Equipment has been saved from the scrap metal merchant somewhere, but that is wishful thinking !
Harvatt
 
#8 · (Edited)
I sailed on a British ship a number of years ago that was fitted with, if my memory is correct, a Plath steering compass, it was entirely unlike any British compass I had sailed with as they all, without exception, were of a standard wooden/brass design. The Plath was encased in a non ferrous metal binnacle and was of a glass bowl design. I cannot remember whether it was dry card or not but as never an air bubble was seen, I presume it was not liquid. It seemed to be very well damped down and the sperical top seemed to illuminate well. It had a patent magnetic adjustment system, comprising control knobs which altered the position of the magnets . I remember after spending a year's charter on the Australian "slave trade" getting two compass adjusters aboard in Port Adelaide prior to heading home. The Plath patent adjustment system defeated them and they ended using string and scotch tape to hold the repositioned magnets. The ex Empire ship had been seriously burned out towards the end of the war and the bridge had been completely rebuilt resulting in the German steering compass being fitted. Many nights I wished we had had a Plath standard compass on the monkey island, as with no radar on a dirty wet night, on a heavily rolling monkey island trying to get accurate cross bearings while the card swung around was a pain in the neck. I felt that the British design had not altered much since the days of Captain Cook.
 
#9 ·
Welcome Harvatt,
We all I am sure glad to see the arrival of a specialist in what to many is truly a "Black Art".
Like many I dream of finding Nautical nuggets in a "Junk" shop, the closest I came was when I saw an old Lifeboat torch, the type with a key on the back for sending Morse Code, is Morse still a requirement at sea these days?
Yours aye,

slick
 
#10 ·
I was on a small tanker recently that had been fitted with an inner skin requiring the addition of a large quantity of new steel. The superintendent could not understand why I insisted that the magnetic compass would require adjustment, instead waving the old deviation card at me which "had not expired".

Even casual comparison between the standard and gyro compasses (allowing for the local variation) can reveal that the deviation card is way out, and I am often left to wonder at the cir***stances in which these cards are produced and appear on ship's bridges.

There is a consensus that the validity of a deviation card is 1 year only and this is something that can often appear of PSC deficiency lists. Correct me if I'm wrong but I do not recall when at sea or taking my tickets the concept of a deviation card expiring unless in cir***stances such as structural alteration and provided that regular checks of the compass deviation are made by the OOW's.
 
#84 ·
One year? That seems to check with the annual dry-docking. I've been with three major companies and we always did a compass adjustment prior to commencing the voyage out of drydock- If you had an extra skin fitted, involving a lot of money, how a superintendent would question the cost of a compass adjustment is beyond me, even for economical reasons, if nothing else.
 
#11 ·
greektoon, seen that a few times, I just say the lifeboats are on the same date but there are NO falls! I Just used to ignore the office rants and ask the master if he was happy, if not, he got whatever he needed. I've even had to, "persuade", some Masters, to tell me what was wrong here and there; generally after I've found the faults or an engineer has tipped me off.
 
#12 · (Edited)
Magnetic Compass. Thank you all so much to those who have so quickly contributed with some interesting comments on this general area.

Sperry , John Lillie & Gillie , Sestrel , B.Cooke , Plath Spherical Compass without a bubble , " Black Art " !! , Beautiful Instrument .

My biggest regret is that I did not keep a diary and do not have a single photograph taken by myself. Suddenly in later retirement I am realising almost to late that this Skill / Trade is rapidly disappearing and there is so much valuable interest in it that cannot by a long chalk be obtained readily in book form . I hope that I can make sfficient time to offer a small contribution . _ To "Binnacle " - your Plath Spherical Compass would not I think be a Dry Card, Probably Liquid Filled, either Oil or mixture of alcohol and distilled water. They generally had to withstand a temperature of -40 to +60 degrees C. They were an excellent piece of instrument engineering. To "Greektoon" - the issuing of a Deviation Card and it`s "Life Span " is a rather long and very technical subject - I will try and pass comment when I can.
Harvatt
 
#14 ·
Sadly the quality of compasses is today poor .......... many made under license .
I had never come across the phenomenon of 'replacing a compass' until the mid 90's.
As has been said all the old stuff was brilliant ! To a worrying degree a magnetic compass is now seen by the ship owner as simply a 'legal requirement' However this is simply not true.. far from it , the Poor old mariner has to put up these days with very poor yet vitally important equipment ............. The influence driven from the perception that 'Well they have all that GPS Stuff' from people who don't sail on the vessel.
Again another worrying trend is lack of records kept by the officer of the watch ie the Compass record book !!!!!!!! Alarming to say the least !!!!
 
#18 ·
Magnetic Compass. To Greektoon - Your "Deviation Card" - just a few thoughts whilst I have a few minutes. Some reasons for Compass Errors being different to those showing on the Deviation Card - Movement or Changes In The Position Of Localized Iron Work , Unsuitable Wiring Around The Compass , Loading vessel With Magnetic Grabs , Electric Welding , Lightning , Vessel Lying In One Direction For A Length Of Time , Type Of Cargo , Placing Of Compass , Ideally, Ironwork should Not Be Less Than 2 Metres Away , The Period In Between Compass Adjustments Is Also Dependent Upon Type Of Vessel. The Deviation Card Informs Any Authority ThatThe Compass Has Been Inspected And Checked For Errors. It must Also Be Born In Mind That As With A Car M.O.T. It Is Only Really Valid For The Time And Place It Was Carried Out On Account Of Factors Such As Those Above. N.B. Add To These - Change Of Latitude And Here Are A Few Factors Causing Compass Error On Board Ship. I had better go now, I do not want to spoil an interesting forum by boring it !
Harvatt
 
#20 ·
Welcome Harvatt, one of a number specialists in truly practical skills, I always thought.

Re Deviation cards - I believe that if they are backed up by frequent compass errors, they have no expiry, provided no major structural alterations are made.

A ship can also quite easily draw up her own over a period, though with some of the PSC inspectors not knowing quite what they are looking at all the time, they might take some persuading.

Looking at many work boats and pleasure craft, I am somewhat astonished to see the compass mounted in front of the wheel, rather than on the centre line.

Best regards.
 
#21 ·
All,
I heard once that if your Cargo was Scrap Iron and was being loaded and or being discharged using an Electro Magnet, then the Magnetic Compass was removed ashore, can anyone confirm this and were there other similar precautions in the case of the use of Electro Magnets.

Yours aye,

slick
 
#57 ·
All,
I heard once that if your Cargo was Scrap Iron and was being loaded and or being discharged using an Electro Magnet, then the Magnetic Compass was removed ashore, can anyone confirm this and were there other similar precautions in the case of the use of Electro Magnets.

Yours aye,

slick
According to the 9th edition of Munro's Seamanship Primer, under 'Loading and discharging by means of electro-magnet';
"the sub-permanent magnetism of the ship may be altered, check the deviation frequently."
It also states, somewhat bafflingly;
"electric suits or steel rings inside officer's caps may cause serious deflection of a ship's compass.
Pat(Thumb)
 
#22 ·
My recent experience is that PSC and Vetting inspectors look for an annually renewed Deviation card. They will generally accept a few months overdue if the error book is filled in every watch including anchor time {which can be considerable these recession days} and shows reasonable errors.
That all seems setting a high standard but I have had 'Compass Technicians' come onboard to renew the card annually who were quite happy to just make out a new card using the old one!
Not in the UK I should point out.
I take comfort that if all my wonderful state of the art bridge gear was knocked out I would still have a simple reliable means of steering a course.
 
#31 ·
John,

Regardless of what IMO may or may not decide at least one of the Oil Majors will always require an independent means to alert watchkeepers if any of their electronic wizardry is going adrift.

In the latest edition of International Marine Transportation's (IMT) Minimum Environmental & Safety Criteria (MESC) published since 1992 for any vessel which wishes to be considered for ExxonMobil or Affilate service, including berthing at any of their or J/V Terminals, the first Navigational Safety requirement states " Vessels MUST have a means to provide warning if the vessel deviates off her intended course; e.g. GPS cross track error, autopilot alarm etc. An independent magnetic off course alarm is strongly preferred." From my own long past experience with ExxonMobil where the term "MUST" is used it never ever means "MAYBE" and "strongly preferred" means that it is a MUST requirement for any term charters and will become a MUST for all vessels in the next edition of the MESC.

It was interesting to note on a very modern vessel (twin ECDIS + INS etc) that I rode on a short voyage last month, for an independent assessment of Navigational & watchkeeping practice, that there was a new Deviation Card displayed, prepared after a full swing off Bergen at the end of last year and that the magnetic compass error was checked and recorded at least once every watch. However, the vessel did not have any other independent means to alert them to a malfunction of the electronics. In my report I recomended that the Owner consider fitting a Magnetic Off-Course Alarm - a relatively inexpensive but fail safe means to fulfil this requirement.

Regardless of state of the art electronics any navigator should recognise the benefits of their Magentic Compass, and it was encouraging to see that on this vessel they understood this fact.

What a great thread this is, initiated by a real expert on the subject. Thanks Havatt.

Regards, Chris Allport
 
#28 ·
To John Tremelling , from my experience , the main de-gaussing coils installed around
the hull and super structure would on their own, have made a huge difference, being
there to neutralize the ship`s magnetic field about and below the water line , to counteract the magnetic mine . This difference between the original and the new situation makes a big difference to any residual compass errors , which in turn is counteracted by fitting coils on the Binnacle. A separate deviation card would be supplied or alternatively a separate set of errors entered on the deviation card itself after having set the coil strength on the binnacle .

harvatt
 
#29 ·
Interesting comment Slick , I have over the years , come across this being done. Logically this should make little or no difference, by virtue of the compass design. The float to which the compass card is mounted is almost like a free floating body , it balances on a pivot , thus allowing it to line itself up with the magnetic field around it .
If we were able to take that field created by the ship`s hull and the electromagnet away, the compass would point to the North . Usually the Compass North will be frozen
to a point on a bulkhead after discharging or loading by this method and take some time
to revert back to normal - if ever ! I new of one vessel which had discharged by this method and believe it or not it sailed from Hong Kong to the Humber with it`s North point
frozen to the wheelhouse forward bulkhead . It made it`s way all that distance by following other vessels and using the Sun and Stars to position find.
Harvatt
 
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