Grade 11 – Nautical Science

October 31, 2020

Tropical storms

Nature. Tropical storms are violent storms with very strong winds and heavy seas. Origin. They occur mostly in the late summer and early autumn (December to April in the southern hemisphere). They originate in the tropics between latitude 5° and latitude 10° north or south and develop only over the […]
October 31, 2020

Ocean currents

Types of current. Unlike tidal currents, ocean currents are not dependent on gravitational effect produced by the interaction of sun and moon. They are caused by the differences in level, or in salinity/density, or in temperature between various masses of water, in which case they are called stream currents, or […]
October 31, 2020

Communications: Distress and safety communications at sea

General. Technology has changed the way we communicate at sea quite considerably. In grade 12 you will be introduced to the Global Maritime Distress and Safety System (GMDSS) but during grade 11 we will be discussing distress and safety communications outside of the new automated system. The old system relied […]
October 31, 2020

Distress frequencies and silence periods

Distress frequencies. For the purposes of safety and distress there are certain frequencies that have been specially reserved for their exclusive use internationally. They are the following: Medium frequency (MF) 518 kHz. Used by coast radio stations to transmit meteorological and navigation warnings and urgent information to ships using the […]