The magnetic compass today – necessary or not?

By Captain Malcolm Goodfellow AFNI ACAA AMPI AMSA Licensed Compass Adjuster

Image from Compass Adjuster - Australia

To many modern day mariners, the magnetic compass is perhaps mostly familiar as an object shrouded in a canvas cover mounted alone on the wheelhouse top with the best view on board. Something akin to a terracotta soldier that might have had a reason to exist in the past but is of no real value today, the magnetic compass is shown little regard or respect. But its importance as an accurate piece of standalone navigational equipment cannot and must not be underestimated.

I for one fully embrace everything modern on modern vessels. As a pilot for many years, I had to utilize and be familiar with all modern bridge equipment on a daily basis, but we should never forget that while the magnetic compass is regulated and mandatory, we must be fully knowledgeable about its use, proper maintenance and compliance. Whenever I have adjusted a ship’s magnetic compass, I always request that either the Master or one of the deck officers assist and observes what I am doing, as an educational opportunity for them. They normally come away quite amazed and appreciative at finding out things they never knew or were taught.

We are all aware (or should be) that ships, and other smaller commercial vessels (in Australia) are required to carry a magnetic compass that either complies with SOLAS Chapter V, Reg 19 or Marine Order Part 27, Part 25 (Safety of navigation and radio equipment), or the National Standards for Commercial Vessels (NSCV). All of these legislative requirements adopt various IMO resolutions and ISO standards for compass design, performance criteria, accuracy and placement on a vessel. Most of these requirements are similarly enforced and adopted by all Flag States and administrations.

To see the decline in the perceived importance of anything to do with the magnetic compass, however, one only has to look to the current STCW requirements for watchkeepers and Masters in Australia. The subject of the magnetic compass is barely covered in theory lectures at maritime colleges any more, and may as well be given to the students in a short handout of just a few pages. One is lucky to find a single simple compass question in any navigation exam. In years gone by, the subject of magnetism and the magnetic compass was a full subject in its own right for Masters, studied over many months and examined fully. Nearly every student’s bookshelf of textbook ‘Bibles’ of the day included The Ship’s Compass by Grant and Klinkert.

As a former AMSA Examiner, I would always give a watchkeeper candidate (and some Master candidates!) a dummy deviation certificate and the variation and ask them to calculate the compass course to steer to make a specific true course. I’m sorry to say that many candidates struggled to work it out. Perhaps the wonderful articles in Compass Wize written by Captain Klinkert many years ago should be mandatory reading for all mariners as a good refresher on the subject.

Observations from PSC

The electronic and technological advances in shipboard navigational equipment over recent years have meant that the average Master and navigating officer is fully consumed with more sophisticated equipment such as GNSS, laser optic gyrocompasses, satellite compasses, ECDIS, ARPA, etc. Too often, the only interaction with the magnetic compass is to record the deviation every watch to satisfy a regulatory requirement for the flag state and to avoid a defect when subject to a Port State Control Inspection.

That said, in my capacity as Port State Control Inspector, it became very obvious to me many years ago that the average mariner did not have much of a clue on anything to do with the magnetic compass. It was common to find defects such as massive deviations exceeding the magic 5°, sometimes 20° or more. Manipulated and erroneous compass error book records were common, and often the most recent compass adjustment had been carried out in regions known to use very dubious methods and standards. I have been told by some Masters that the last adjustment was done in a place where the adjuster did not even require the vessel to leave the wharf. Another Master told me that one compass adjusting company asked for the Master to send photos of the binnacle and the magnet placements and a copy of the compass error book. The adjuster would then email instructions on how to adjust the compass by moving the magnets, and then would forward the official deviation certificate to the Master. Why a Master or company superintendent would allow a practice like this to occur is another question entirely. Unfortunately, there are those who should know better, but who lack the knowledge to discern what is right and what is unacceptable.

Logbooks and compass checking

I have yet to believe the shipboard compass record commonly found in some ship’s compass error book entries that shows ‘overcast and no error taken’ for days on end at sea. One only has to cross check this against the recorded weather entries in the deck logbook for the day in question to expose what is really going on. This of course also reflects on the Master for allowing this lazy and fraudulent practice to continue. Taking a compass error is one of the quickest and easiest of navigational practices, so the reluctance to do so is mystifying.

Even if a compass error cannot be taken for legitimate reasons, at the end of every watch or alteration of course, the officer of the watch will hopefully record in the deck logbook the Gyro Heading, True Heading and Compass Heading. The deviation computed from these comparisons of headings can be entered into the compass error book and annotated as such.

In many places, compasses can still be checked even when the weather does not cooperate. One compass adjuster colleague told me of a practice he used when on a particular run near the coast which was nearly always in overcast weather. He would obtain the exact position of a lighthouse from the relevant List of Lights, then enter this position into the GPS (in effect a separate waypoint). In this way, the exact true bearing was always available to compare with the compass bearing to calculate the compass error. So simple and so easy.

How many deck officers compute the deviation by taking a gyro error on the bridge wing repeater, working back to compare the gyro heading converted to a true heading at the steering position, and then looking through the reflector periscope of the standard compass to check the compass heading to then determine the compass error, applying the variation and then working out the deviation? This all sounds so familiar, but of course is flawed in principle and theory.

I shared my thoughts about this process with an esteemed passenger ship Master who I knew very well, who to his officers’ horror, made them take magnetic compass errors directly from the standard compass binnacle from then on.

When technology fails

I could recount a number of incidents of modern vessels suffering power issues resulting in major failure issues with the gyro compasses. Satellite compasses of course can also be subject to errors and aberrations in accuracy due to satellite signal aberration and atmospheric issues. Should this ever occur, what do we have to fall back on? A properly functioning and corrected magnetic compass!

I have sailed on a vessel where our gyro failed and could not be repaired for a couple of months, and all courses were steered by the magnetic compass. Not an issue at all if you are familiar with the instrument and how to work out a compass course to steer. Of course, none of this was any issue for those who sailed on merchant ships prior to the general introduction of gyrocompasses on merchant ships post World War II.

I can almost hear the usual sceptics mumbling, ‘We don’t need a magnetic compass on a vessel anymore with all the electronic aids we have. Next thing he will want us to be able to use the hand lead line again or stream a Walker’s towed log!’  No doubt some of the younger tech savvy mariners might say, ‘My iPhone has a magnetic compass app on it, what is wrong in using that instead of worrying about the standard compass?’ Are they aware that the 3-axis magnetometer built into the phone is still subject to any external magnetic field, and its use on a vessel (particularly one made of steel) is flawed to say the least? I am sure a professional and competent mariner will want to understand and appreciate the magnetic compass, to have an idea of when it is performing correctly, is adjusted correctly and of course the limitations of the instrument.

Hopefully what I have briefly mentioned above will encourage the mariner of today to take a renewed interest in one of the most important pieces of navigational equipment on board. Embrace all of modern technology certainly, but also be an astute and professional mariner who understands all of the equipment on board, including the magnetic compass.

About the author:

Malcolm Goodfellow currently teaches at the Maritime School in Newcastle (TAFE), where he delivers courses at all levels—from Watchkeeper to Master (Unlimited). His areas of expertise include coastal and celestial navigation, ship handling on the simulator, and maritime law.

Malcolm began his maritime career as a deck officer and later served as a Master at sea. He went on to work with the Australian Maritime Safety Authority (AMSA) as the Survey Manager for Newcastle and as an Examiner of Masters and Mates. Before retiring from piloting, he spent 19 years as a Senior Training and Check Pilot with the Port Authority of NSW in Newcastle.

Malcolm is also one of the editors of the current Australian Boating Manual (6th edition).

This article on the magnetic compass was originally published in Seaways, the magazine of The Nautical Institute. We thank Malcolm for kindly granting permission to share it here.

Photo provided by Captain Malcolm Goodfellow