Survival Equipment

                                Gravity davit

Lifesaving equipment on board ship, apart from smaller items such as lifebuoys and lifejackets, consists of lifeboats and liferafts. Lifeboats are rigid vessels secured into davits which enable the boat to be launched over the ship's side. Liferafts are inflatable vessels, usually stowed on deck in canisters which must be thrown overboard, whereupon they are automatically inflated. 

Lifeboat accommodation for all the ship's crew must be provided on both sides of the ship. This is to allow for a situation when only the boats on one side can be lowered. The boats must be more than 7.3 m long and carry sufficient equipment and provisions for survival for a reasonable period. This would include oars, a boat hook, a compass, distress rockets, first aid equipment, rations and fresh water. 

They must also be partially or totally enclosed, self-righting and equipped with an engine. Lifeboats on cargo ships of 20 000 tons gross tonnage and above must be capable of being launched when the ship is making headway at speeds up to 5 knots. A new requirement for all new ships is that a rescue boat, capable of being launched in five minutes, must be carried. 

This boat is to be used to rescue persons from the sea and also to gather together the lifeboats, Lifeboat davits are provided as stowage for the lifeboats which can readily be released to lower the boats without any mechanical assistance, 'Gravity davits', as they are called, slide down and position the boat for lowering as soon as they are released. 

 Liferaft

The davits must be able to lower the boats when the ship is heeled to 15° on either side. The lifeboat is held against the cradle by ropes called 'gripes'. Another wire, either separate or combined with the gripes, holds the cradle in its upper position. With the gripes and the cradle securing device free, the winch handbrake can be released to enable the cradle to slide down and over the ship's side. 

Also Read ➤  Tank Stabiliser

A tricing-in pendant (a wire) bring the lifeboat close to the ship's side to enable it to be boarded. The bowsing lines which fasten to each end of the lifeboat are then used to hold it in to the ship's side, the tricing pendant then being released. Once the crew are on board the bowsing lines are released and the lifeboat lowered to the water. The wires which raise or lower the boat are called 'falls' and the speed of descent is restricted to 36m/min by a centrifugal brake. 

The handbrake used to lower the boat has a 'dead man's handle' or weighted lever, which, if released, will apply the brake. Liferafts are normally provided to accommodate all of the ship's complement. They are usually stored in cylindrical glass-reinforced plastic containers which are secured on chocks on the deck. 

Inflation takes place automatically when the container is thrown overboard, the container bursts open and the liferaft floats clear. A pressurised cylinder of carbon dioxide is used to inflate the raft. where it can be seen to be a well equipped totally enclosed arrangement. The survival equipment located in the raft is similar to that provided in lifeboats. 

Liferafts must normally be boarded from the water unless they are of a special type which is lowered, fully inflated, by a davit; but it is not usual to fit this type on cargo vessels. Liferafts must be stowed in such a way that they will float free and inflate if the vessel sinks. A hydrostatic release is normally used which releases the lashings at a predetermined depth of water.

Whistle 

International regulations require audible signals to be made by a ship in conditions of poor visibility. The ship's whistle is provided and arranged to give prolonged blasts at timed intervals when operated by a hand control. The compressed air acting on the diaphragm causes it to vibrate and the sound waves are amplified in the horn. 

The control system associated with the whistle can provide whistle operation as long as any of the operating switches is in the 'on' position. Alternatively short blasts can be given by on-off operation, since instantaneous cut-off occurs after each blast. A more sophisticated control system incorporates timing gear which provides a prolonged blast every two minutes, or other arrangements as required. 

The whistle switches are usually on the bridge wings and inside the bridge. The whistle is also arranged for direct operation from a lanyard which extends from the bridge. The compressed air supply can vary in pressure over a considerable range without affecting the whistle operation.