A good seaman knows about all the weapons on his ship and when to use them. Study hard, sailor!

4.7 inch cannon Mk ix - The 4.7 inch gun is the largest cannon on a destroyer. Destroyers routinely carry five to eight of these in single or double rotating turrets. This cannon fires shells that are 4.7 inches ( 12cm ) in diameter and weigh 50 lbs (22.6 kg). An experienced crew can load and fire up to 12 rounds a minute with a maximum range of 15,000 metres. The guns could be loaded with starshell flares, high explosive or semi-armour piercing rounds

21 inch Mk ix torpedo - This is a destroyer's only useful weapon against larger ships. The torpedo was 55cm in diameter, 7.3 metres long, with 365 kg of high explosive in the front. Torpedoes were launched from tubes mounted on the ship's deck, using pressured air. Once in the water the torpedo's fuel-injected kerosene motor took over. A Mk IX had a speed of 36 knots (67 kph) and a range of 9,600 metres. Destroyers carried four or eight torpedo launchers.

Mk vii Depth charge - A depth charge consisted of a drum with 130 kg of high explosive inside. A dial allowed the crew to set the depth the charge would explode at. A depth charge had to explode within 8 metres of a U-Boat to cause major damage, but repeated depth charge explosions could force a submarine to surface. Depth charges were launched by "Y" or "K" guns or dropped off stern racks. In 1942 the Allies developed the "Hedgehog" anti-submarine mortar system. It fired 24 mortar shells at once in a pre-set pattern and the shells only exploded if there was a contact.

40 mm Bofors gun - This was a ship's primary anti-aircraft weapon. A Bofors gun fired 1 kg, 40 mm shells at a rate of up to 100 rounds per minute. Bofors shells were effective up to an altitude of 4,000 metres. Destroyers carried between two and six Bofors guns in single or double mounts.

20 mm Oerlikon SS gun - This was essentially a heavy machine gun. It could be used against close-up air craft attacks or against small surface targets where very quick aiming was essential. It could fire up to 350 rounds a minute with a range of 1000 metres. Destroyers carried between two and eight Oerlikons.