Question 1. What is a 'Mason's hygrometer' and what is it used for?

Answer: It is the name given to dry and wet bulb thermometers, usually contained in the Stevenson's screen often found on the ship's bridge wing. It is used for measuring the 'humidity'.

Question 2. For what would you use a hydrometer when aboard ship?

Answer: A hydrometer is used to obtain the density of dock water. The obtained value is then used in conjunction with the Fresh Water Allowance (FWA) to obtain the Dock Water Allowance, i.e. the amount that the vessel may submerge her load line mark, in any water other than sea water.

Question 3. When reading the precision aneroid barometer, what corrections would you make to the reading?

Answer: The barometer is supplied with a calibration correction card which allows for a correction to be added to the reading to adjust to mean sea level (table of height in metres air temperature in C).

Question 4. How would you check that the azimuth bearing circle, of the compass was correct?

Answer: By taking a bearing of a terrestrial object, e.g. a lighthouse, with the arrow indication uppermost. Take a second bearing of the same object, with the arrow in the downward position.

Both readings should be the same and the bearing circle can be used with confidence.

Question 5. What is the liquid found inside a magnetic compass bowl?

Answer: The...