Understanding Sextant
Dec 18, 2025



A sextant is a navigation instrument used by seafarers to measure the angle between a celestial body (sun, moon, star) and the horizon.

The sextant is used to determine a ship’s position at sea, specifically latitude and longitude, by celestial navigation—especially when GPS is unavailable. Old-school, but still gold 🧭

Parts of a Sextant
Frame – The main body that supports all parts of the sextant.
Telescope – Used to view the horizon and the celestial body clearly.
Index Mirror – Reflects the image of the celestial body.
Horizon Mirror – Allows the observer to see both the horizon and reflected image at the same time.
Index Arm – Movable arm used to adjust the angle being measured.
Graduated Arc – Curved scale where angles are read in degrees.
Drum (Micrometer Drum) – Fine adjustment for precise angle readings.
Locking Device – Secures the index arm in place after adjustment.
Glass Filters – Protect the eyes when observing bright objects like the sun.

A sextant is a precision navigational tool that helps mariners calculate their position at sea by measuring angles between celestial bodies and the horizon.

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WHAT IS ECDIS?

ECDIS stands fo ELECTRONIC CHART DISPLAY AND INFORMATION SYSTEM replaces traditional paper nautical charts with a digital interface that complies with International Maritime Organization (IMO) standards. It uses data from GPS, radar, AIS (Automatic Identification System), and other sensors to give the ship's crew a detailed and accurate picture of their surroundings and navigation route

Voyage Data Recorder (VDR)

The Voyage Data Recorder (VDR) is a critical safety device installed on board ships, often referred to as the vessel’s “black box,” similar to those used in aircraft. Its primary function is to continuously record essential data related to a ship’s operation, navigation, and surrounding environment. The VDR is required under the International Maritime Organization (IMO) regulations, specifically the Safety of Life at Sea (SOLAS) Convention, for most commercial vessels. A VDR captures a wide range of information, including bridge audio, VHF radio communications, radar images, ship speed, heading, engine orders, alarms, and GPS position. This data is securely stored in a protective capsule designed to withstand extreme conditions such as fire, impact, and prolonged submersion in water. In the event of a maritime accident, collision, grounding, or near-miss incident, the recorded data can be retrieved and analyzed by investigators.

Methods of Heat Transfer

/ Methods of Heat Transfer Understanding how heat moves is essential in science, engineering, and everyday applications especially in marine and industrial environments. Heat transfer occurs in three fundamental ways: conduction, convection, and radiation. Each method explains how thermal energy flows from one object or area to another. / Conduction is the transfer of heat through direct contact. When two objects touch, heat moves from the hotter object to the cooler one as particles collide and transfer energy. This process is common in solids, such as metal cookware heating up when placed on a stove.

PERSONAL LIFE SAVING APPLIANCE

The International Life-Saving Appliance Code, known as the LSA Code, is the technical backbone of Chapter III of the SOLAS Convention, setting the global standard for life-saving appliances carried on board ships. It was created to ensure uniform safety requirements across the maritime industry, covering the design, construction, and performance of all critical survival equipment. Its scope includes personal protective gear such as lifejackets, immersion suits, anti-exposure suits, and thermal protective aids; visual signaling devices like parachute rockets, hand flares, and buoyant smoke signals; as well as survival craft, rescue boats, launching appliances, marine evacuation systems, line-throwing devices, and general emergency alarms. By harmonizing specifications worldwide, the LSA Code ensures that seafarers and passengers can rely on equipment that functions effectively in emergencies, regardless of where a vessel is registered or built. Since its adoption in the late 1990s, the LSA Code has been continuously updated to incorporate new technologies, lessons learned from incidents, and advancements in safety engineering. Earlier consolidated editions captured amendments to survival craft standards, performance requirements for lifejackets, and the inclusion of improved thermal protection. Over time, revisions have refined lifeboat release gear standards, introduced stricter testing procedures, and improved design features for ease of use and reliability. These updates reflect the constant commitment of the international maritime community to keep safety requirements relevant and aligned with practical challenges at sea. As of 2025, the LSA Code has seen further refinements that enhance its application to modern vessels. One of the most significant ongoing developments concerns ventilation requirements for partially enclosed lifeboats, aimed at ensuring carbon dioxide concentrations remain at safe levels for all occupants. Another focuses on the safe simulation of free-fall lifeboat launches, requiring test devices to withstand high shock loads with reinforced safety factors. These amendments, expected to take effect in the coming years, highlight the Code’s proactive stance on addressing risks even before they become widespread problems. The continuous improvement process reflects the IMO’s recognition that evolving ship designs and operating environments demand equally evolving safety equipment. Beyond these technical adjustments, the LSA Code provides very detailed requirements for the construction and outfitting of life-saving appliances. Liferafts, for example, must be capable of carrying a minimum of six persons, provide adequate ventilation even when entrances are sealed, and include systems for rainwater collection, radar transponder mounting, and external lifelines. Containers must be clearly marked depending on the voyage type, and painter lines must meet specific strength requirements to ensure safe deployment. Similarly, thermal protective aids are required in survival craft to guard against hypothermia, while immersion suits and lifejackets must not only provide buoyancy but also visibility, durability, and ease of donning under emergency conditions. Altogether, the LSA Code forms a dynamic and indispensable framework that ensures life-saving appliances are reliable, standardized, and effective across the global fleet. It demands rigorous testing, marking, and maintenance regimes to guarantee that equipment performs when needed most. By mandating clear performance benchmarks and updating them regularly, the Code ensures that every seafarer and passenger has the best possible chance of survival in an emergency. As shipping continues to evolve, the LSA Code remains at the center of maritime safety, embodying the SOLAS principle that the preservation of human life at sea is paramount.

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