Understanding Sextant

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.

Litmus Test

Litmus Test What is a Litmus Test The litmus test is a simple method used to identify whether a liquid is acidic, neutral, or alkaline (basic). It uses special paper called litmus paper that changes color when dipped into a solution. There are two types of litmus paper: blue litmus paper and red litmus paper. A universal pH paper can also be used to show a wider pH range using color changes. Purpose The litmus test is used to quickly check the chemical nature of a liquid. It helps determine if a substance is safe to handle or suitable for use in systems such as water treatment, cleaning, or maintenance. How It Works Blue litmus paper turns red in an acidic solution Red litmus paper turns blue in a basic (alkaline) solution Universal pH paper changes color based on the pH level

RESERVE BUOYANCY

RESERVE BUOYANCY Reserve Buoyancy refers to the additional buoyant force available in a vessel beyond what is required to keep it afloat at its current load. It is the watertight volume of a ship above the waterline that helps the vessel remain stable and safe, especially during rough seas, flooding, or added weight. Buoyancy ●The upward force exerted by water that keeps a ship floating. ●It is created by the displacement of water equal to the ship’s weight. Reserve Buoyancy ●The enclosed, watertight volume above the waterline. ●Provides extra floating ability if the ship takes on additional load or encounters heavy weather. ●Critical for safety and survivability. Waterline ●The line where the hull meets the surface of the water. ●Indicates how deep the ship is sitting in the water.

WILLIAMSON TURN

The Williamson Turn is a maneuver used to reverse the course of a vessel and return along its original track. It is primarily applied during Man Overboard (MOB) situations, especially when the exact position of the casualty is uncertain or when visibility is poor, such as at night or in fog. Purpose: • To bring the ship back onto its previous course line, improving the chance of relocating the person who fell overboard. • Ensures the vessel returns to the point of incident efficiently and safely. • Helps maintain visual and navigational reference in low-visibility conditions. Procedure: 1. Apply full rudder toward the side where the person fell overboard. 2. Allow the vessel to deviate 60° from its original course. 3. Shift full rudder to the opposite side. 4. Continue the turn until the vessel is heading about 20° from the reciprocal (opposite) course. 5. Return rudder to midships. 6. Steady the vessel on the reciprocal course and proceed back along the original track to search for and recover the casualty.