Navy questions

On the night of 31 May – 1 June, three Japanese Ko-hyoteki-class midget submarines, each with a two-member crew, entered Sydney Harbour, and attempted to sink Allied warships, ultimately killing 21 sailors.

The knot is a unit of speed equal to one nautical mile per hour, exactly 1.852 km/h. The ISO standard symbol for the knot is kn. Worldwide, the knot is used in meteorology, and in maritime and air navigation—for example, a vessel travelling at 1 knot along a meridian travels approximately one minute of geographic latitude in one hour.

The Long Range Acoustic Device (LRAD) is an acoustic hailing device developed by LRAD Corporation to send messages and warning tones over longer distances or at higher volume than normal loudspeakers. LRAD systems are used by law enforcement, government and defense agencies, as well as maritime and commercial security companies to broadcast audible notifications and warnings over distance.

OOCL Hong Kong is the largest container ship yet built and the third container ship to surpass the 20,000 Twenty-foot equivalent unit (TEU) threshold. She was built at the Samsung Heavy Industries, Geoje shipyard with yard number 2172 and delivered in May 2017.

The USS Gerald R. Ford (CVN 78) was delivered to the US Navy in May 2017, while initial operational capability is anticipated to be achieved in 2020. Its full load displacement is 100,000 t. It has the capacity to carry more than 75 aircraft, and can accommodate 4,539 personnel including ship’s company, air wing and other support staff.

Eurybiades was the son of Eurycleides, and was chosen as commander in 480 BC because the Peloponnesian city-states led by Sparta, worried about the growing power of Athens, did not want to serve under an Athenian despite the Athenians' superior naval skill. For all the enmity between the two, Eurybiades was ultimately assisted by the Athenian naval commander Themistocles.

Queen Anne's Revenge was a fully rigged ship, most famously used as a flagship by the pirate Blackbeard (Edward Teach). Although the date and place of the ship's construction are unclear, it is believed she was built in Bristol in 1710 and named Concord. Blackbeard used the ship for less than a year,[5] but captured numerous prizes using her as his flagship.

Mikasa is a pre-dreadnought battleship built for the Imperial Japanese Navy. After 1922, Mikasa was decommissioned in accordance with the Washington Naval Treaty and preserved as a museum ship at Yokosuka. Mikasa is the last remaining example of a pre-dreadnought battleship anywhere in the world.

CQD is one of the first distress signals adopted for radio use. Although used worldwide by Marconi operators, CQD was never adopted as an international standard, since it could be mistaken for a general call "CQ" if the reception were poor. Germany's Notzeichen distress signal of three-dots/three-dashes/three-dots was adopted as the international Morse code distress signal. (This distress signal soon became known as "SOS" .

The Spanish Armada was a Spanish fleet of 130 ships that sailed from La Coruña in early summer 1588, with the purpose of escorting an army from Flanders to invade England. During Battle of Gravelines the Spanish fleet was damaged and forced to abandon its plans.