May 16, 2023
No Comments
The magnetic compass plays a very vital role in maritime navigation. As per SOLAS Chapter 5, Regulation 19 “all ships irrespective of size shall have a properly adjusted standard magnetic compass or other means, independent of any power supply to determine the ship’s heading and display the reading at the main steering position”. Owing to the exposure of the magnetic compass to the weather and harsh conditions, it becomes necessary to safeguard the compass. The navigation instrument that helps serve this purpose is the binnacle. Alongside this aid, binnacles also safeguard the compasses from toppling over due to the constant rolling and pitching of the vessel.
The binnacle is a cylindrical container made of non-ferrous material that houses the different components of the magnetic compass and that as a whole. Earlier, wood was used for the construction of the binnacle. The compass bowl is housed in the top part of the binnacle whereas the middle part is accessible through a door housing the corrector magnets extending to the projector towards the forward.
Binnacles have been in utilization since the 1700s. Over the years though, several developments to the technology of binnacles have been carried out to suit the developments in the vessels’ building technology. The instrument consists of a round stand upon which a plinth is mounted. Separate divisions constructed, store the compass and other navigational equipment on the plinth of the binnacle.
A ship binnacle is positioned right before the helmsman’s line of vision. The compass and all other navigation equipment are safeguarded within the binnacle, making it easy for the steersman to observe and steer the vessel accordingly. For this purpose, binnacles have always been constructed to come up to the waist of steersmen handling the vessel.
In the centre part of the lower half of the binnacle are contained many holes which contain inside them corrector magnets to negate disturbing effects of magnetism caused by the hull of the ship. The specifications of the corrector magnets are decided by an authorised ‘compass adjuster’ whose services are usually called upon in port. The access door to these corrector magnets must be kept locked at all times unless when needed to be opened for adjustment.
The Flinders Bar is a soft iron corrector vertically placed in the for’d or aft part of the binnacle depending on the extension of the superstructure area abaft of or forward of the binnacle. The length of the bar may be changed during adjustment of the compass.
The Quadrantal Correctors are two soft iron spheres fitted in brackets on either side of the binnacle. Again, the distance between the quadrantal correctors can be altered during adjustent of the compass.
The helmet is fitted on top of the binnacle and is non-ferrous. This is in place to protect the compass bowl from the weather and harsh conditions.
Following steps should be taken to remove bubbles:
The magnetic compass is housed on the monkey island and the compass course needs to be viewed from the bridge. The compass projector is in place to enable the same via subsequent reflections. It is in place to enable the helmsman to in the wheelhouse to view the coincident compass card reading and lubber line to steer the ship correctly.
While binnacles refer to navigation instrument, the term ‘binnacle lists’ refers to those seafarers who have been relieved from duty on a particular day on account of medical unfitness.
Ref: Bridge Equipment, Charts and Publications by Capt. H. Subramaniam
We believe that knowledge is power, and we’re committed to empowering our readers with the information and resources they need to succeed in the merchant navy industry.
Whether you’re looking for advice on career planning, news and analysis, or just want to connect with other aspiring merchant navy applicants, The Marine Learners is the place to be.