‘Sailings’ is a term given to various methods used to determine courses and distances to be steamed when travelling from one geographical position to another. There are six different “sailings”, ie Parallel, Plane, Middle Latitude, Mercator, Great Circle and a combination of Great Circle and one of the others. During this course, however, we will…
This website has been compiled for the guidance of and use by grade 11 learners taking Nautical Science as one of their secondary school subjects. It follows the approved national curriculum for the subject and comprises four parts, namely Navigation, Seamanship, Meteorology and Communications. Although it has been written for grade 11 learners, it forms…
By parallel sailing we mean travelling along a parallel of latitude from one place to another. This means that one would either be travelling directly westward or eastward [270° (T) or 090° (T)]. The distance along a parallel of latitude between two particular meridians decreases as the meridians converge towards the poles. The distance decreases…
Each GMDSS ship station is allocated its own unique nine digit MMSI number which is included automatically in each DSC call made by the station. Included in the MMSI number are the maritime identification digits (MID) which identify the country licencing/controlling the station. Three types of MMSI numbers are in common use to identify individual…
It is compulsory for SOLAS vessels to have GMDSS equipment. This includes all passenger vessels and cargo vessels of 300 gross tons and above on international voyages. There are also a very large number of vessels that don’t undertake international voyages and do not have to comply with GMDSS, ie fishing vessels, warships, yachts, etc.…
As far as the availability of equipment is concerned, there are three options: At sea maintenance. Shore based maintenance. Duplication of equipment. Ships operating in areas A1 and A2 must nominate one option. Ships operating in areas A3 and A4 must nominate two options. Details of the options applicable are contained in the radio safety…
Deck officers should have the following knowledge/ability: A detailed knowledge of the operation of all GMDSS sub-systems and equipment. The ability to send and receive messages correctly by radio telephone and NBDP. A detailed knowledge of the regulations applying to radio communications. A knowledge of the documents relating to the charges for radio communications. A…
The minimum operator requirements for vessels is as follows: ships operating within range of a VHF coast station – ROC (Restricted operator certificate). ships operating beyond the range of VHF coastal stations – GOC (General operator certificate). The international convention on STCW require that all deck officers shall hold an appropriate qualification to operate VHF…
The GMDSS is designed to perform 9 functions: Transmission of ship to shore distress alerts by two separate and independent means. The details for this function are contained on the individual ship’s radio safety certificate. For example, a ship in area A1 would use VHF DVS equipment as the primary means and the EPIRB as…
The GMDSS system is made up of five sub-systems as follows: DSC (digital selective calling) terrestrial communications system. Dedicated frequencies are made available for maritime communications operating in the VHF, HF and MF radio bands. This provides long, medium and short-range communications. Use is made of DSC technology which provides a means of calling a…