DAMAGE CONTROLOf the vessel

In navies, merchant shipping and the maritime industry, DAMAGE CONTROL is the emergency control of situations that may cause the sinking of a ship.

Fire; Explosion; Collision; Grounding; Steering gear failure; Machinery damage, Main Engine failure; Blackout, Hostile action directed at the ship (terorrists, saboteurs, pirates).

"There is no danger that Titanic will sink. The boat is unsinkable and nothing but inconvenience will be suffered by the passengers.“ Phillip Franklin, White Star Line vice-president, 1912

The recent Costa Concordia incident showed : "No matter how safe a ship is, if you drive in full speed into a rock it is likely to sink.”

It is important to be aware of the general principles of DAMAGE CONTROL. You also need to understand the concept of reserve buoyancy and its relevance to DAMAGE CONTROL.Reserve buoyancyBuoyancy holds a ship up in good or bad weather. When water seeps or floods into a ship's interior, the vessel is slowly robbed of buoyancy and, eventually, it will be dragged under by its own weight unless the leak can be plugged. Ship designers build different amounts of RESERVE buoyancy into a ship, depending on its expected operating conditions;- River ships 10-15% of the displacement- Merchant ships 20-40%- Warships > 100%

Every boat must have sufficient RESERVE buoyancy to operate safely: do not overload your vessel. Commercial vessels have a load line assigned to them and it is an offence to proceed to sea with this loadline submerged.This line is sometimes know as the Plimsoll Line, after Samuel Plimsoll who campaigned heavily for the safe loading of ships in the 1870s.

The buoyancy of a ship can be judged in terms of its "freeboard“, which is the distance the ship rises above the waterline. The more buoyancy a ship has in proportion to its weight, the greater its freeboard and the higher it floats in the water. Most important, freeboard enables a ship to recover after being slammed by a monster wave. This is called its reserve buoyancy, in rough conditions, the more freeboard you have, the better off you're going to be.

Ch.I Unsinkable vessel - 21hrs 1. Unsinkable vessel. Underwater damages to the hull. (4hr)Intact Stability The vessel is in normal operational configuration. The hull is not breached in any compartment. The vessel will be expected to meet various stability criteria such as GM (metacentric height-Initial Static Stability), area under the GZ curve (righting lever) /Dynamic Stability/, range of stability, trim, etc.

“Unsinkable vessel“ /seagoing qualities of Damaged ship/- the ability of the ship after partial flooding to keep in some degree all their seagoing qualities: stay afloat/ keep buoyancy /, not capsize/turnover/, to be able to steer/and run/ and strength of the ship.UV = RB + Stab + Ste + SS The ability of the ship to stay afloat may deteriorate due to lost of Reserve buoyancy and Stability, caused by underwater and freeboard damages, intentional/ unintentional water intake, loading/discharging of goods, sailing in storm conditions.

Underwater damages in the hull of the ship-lead to flooding of compartments with a change in reserve buoyancy and stability-change of the draft, list, different -the lost of transverse stability is more dangerous than longitudinal stability-additional threat is hydrostatic Inrush/head/pressure on the flooded compartment’s bulkheads

Flooding of large bow or stern compartments can lead to a substantial reduction in longitudinal stability/13Feb2004 m/v Hera sank in Black sea at the entrance of Bosphorous/

Stability depends of -quantity of water intake-the possibility of free overflow-relationship with overboard waterOfficers should be aware of the rate of inflow water through a gash/hole/. Rate = A square rootH - tons/second 7A - the area of the hole in square feetH - the depth below sea level in feetGash- cut, flaw, opening, holeInrush- pressure, head, stress, push

Watertight compartments are categorized as:

I. Compartment 1st category -fully filled compartment

/connected or not with overboard water/, located below the waterline, covered by a waterproof top deck (DBT),the intake water we consider like acceptance of solids, noFSM. GM increases

II. Compartment 2nd category - partially filled and have no connection with overboard water. The water in them is constant, but during the rolling it blends/overflow, leading to a reduction in stability.

III. Compartment 3rd category - filled partially and have a connection with overboard water. The level of water in them is always equal to the level of overboard water.

2. Freeboard damage to the hull, loading (discharging) of cargo, handling and sailing in adverse weather conditions/bad weather, heavy seas/ as reasons leading to lost of RESERVE BUOYANCY and STABILITY – 2hr

Freeboard damage to the hullDamage to the hull above WL is considered that the freeboard decreased and the volume of surface part becomes smaller in magnitude/value/ equal to the volume of the damaged compartments.

If the watertightness of freeboard and watertight bulkheads of ship are violated, then listing to the heeling angle at which the damaged part of the board going into the water compartments flooded, the diagram of a static resistance is interrupted and the ship sinks. Freeboard water resistance of the ship is necessary to ensure its buoyancy at large angles of heel.

Intentional intake of water

Firefighting - Flooding compartment to extinguish fire or to prevent from list. If the water is promptly discharged overboard buoyancy will not deteriorate, otherwise reserve buoyancy / volume / and stability are reduced.

Loading (discharging) of cargo•Icing of the vessel - due to negative temperatures wind and waves.

The sea hits the hull and form a cloud of water spray. Icing occurs rapidly at temperatures -8C and wind over 15 m / sec.Depending on the part of the icing ship can get heel and / or trim and reducing of stability (GM)To prevent icing, the ship have to leave danger area or to maneuver with speed and course to avoid spraying and icing. In all cases the ice have to be removed.Neutral plane – in most of the vessels is near the plane of WL. When accepting cargo below the NP, (GM) increases and vice versa.In the process of exploitation the stores / fuel, water ... / aremodified / decreased /, which leads to reduced stability, but also in the occurrence of free surfaces. /ballasting, transfer of fuel to service tanks/.

Moving loadsDuring the operation of the ship is often necessary moving loads in any direction, weight and buoyancy of the vessel do not change in size, but there are change in applied points which modify the stability and position of the ship.The vertical transfer of the load shall change only metacentric heightGM1 = GM -p / P . (Z2-Z1)When moving up the stability decreases.When moving down the stability increases.

At horizontal transfer of the load center of gravity is also moved in a horizontal positionGG1 = p / P . (Y-Y1)As a result of transfer CG /center of gravity/of the vessel moved from G to G1 and couple forces appeared whose moment tilted the ship to the side of the transfer of the load.

Sailing in adverse/bad/ weatherStorm - weather conditions, when the sea state and the wind reached such intensity and power that can cause rolling of the ship with unwanted or dangerous consequences.Storm - Beaufort scale/sea meteorology/wind - 88.1–102.4 km/h (24.5–28.4 m/s)Wave height - 9–12.5 m

Shaking of the ship can cause:- Capsizing of vessel as a result of excessive heel due to wind effect accompanied by a loss of stability- Breaking of hull as a result of excessive stresses from bending during pitching- Washing of the deck and infiltration of water into the internal spaces- Local destruction or damage to hull, individual equipment, devices and mechanisms due to theinertial overloads or hits of the waves.

- Reducing the ship’s speed- Deterioration of living conditions, painful physiological effects

Slamming - hydrodynamic hits in the bottom /the bow or stern/. The strongest hits in the bow. Often accompanied by hull shocks and vibrations.She can obtain local bottom and side shell plating damages.

The water on deck may be considered as high liquid load with a large surface area, which decrease stability and reserve buoyancy.

Sailing in directional wave - if the course of vessel and direction of the waves coincide, stability can decrease. The danger is greatest when the speed of the vessel and her length coincide with the speed and length of the wave.

Statistically such accidents are most common in vessels under 60 meters (15-35m).Besides reducing GM deteriorate controllability of vessel / wave uncovers long time screw and rudder /

Reasons that cause worsening of seagoing qualities

Flaws in the hull sealing.Improper actions with drainage and drainage systemFree surfaces of fuel tanks

3. Constructive measures to ensure the “unsinkable vessel”/seagoing qualities of DV/. Systems ensuring seagoing qualities-2 hr

Providing seagoing qualities

A. Sufficient reserve buoyancy- River ships 10-15% of the displacement- Merchant ships 20-40%- Warships > 100%

B. Separation of waterproof volumes/ watertight bulkheads; transverse and longitudinal /

Watertight compartments / if punctured(holed) to be flooded only one of them / Forepeak, Afterpeak .......Some passenger, military and other ships are designed with longitudinal bulkheads. If such compartment is flooded the vessel listed.The large number of bulkheads makes the hull too heavy, reduce load capacity, makes the vessel more expensive, loading / discharging operations became more difficult due to reduction of cargo holds and cargo hatches.

THE DIFFERENT DAMAGE CONTROL SYSTEM

1. Drainage and flooding system.2. Fire Main and Sprinkling system.3. Ventilation system.4. Fuel and fresh water system.5. Compressed Air system.6. Communication system. 7. Emergency power

Systems providing unsinkable vessel

Ballast System - designed for reception of overboard water in the empty bottom , side , end tanks/ FP; AP / to ensure stability , provide adequate heel and trim of the ship and discharge of these amounts of water when the ship loads - powerful centrifugal pumps 600-700m3 / h.

Bilge systems Designated for discharge of water accumulated in the compartments during a daily operations or as a result of an accident. Arrangements of bilge main - The bilge main is arranged to drain any watertight compartment other than ballast, oil or Fresh water tanks and to discharge the contents overboard. The number of pumps and their capacity depend upon the size, type and service of the vessel.

All bilge suctions must be fitted with suitable strainers/filters/, which in the machinery space would be mud boxes positioned at floorplate level for easy access. The emergency bilge suction or bilge injection valve is used to prevent flooding of the ship. It is a direct suction from the machinery space bilge which is connected to the largest capacity pump or pumps. An emergency bilge pump is required for passenger ships but may also be fitted as an extra on cargo ships. It must be a completely independent unit capable of operating even if submerged.

A centrifugal pump is usually used, driven by an electric motor. The power supply is arranged from the emergency generator. A typical system is shown in Figure . The various pumps and lines are interconnected to some extent so that each pump can act as an alternative or standby for another.

Pumps. Types of pumpsA pump is a device that moves fluids (liquids or gases)I.According to the method they use to move the fluid-direct lift-displacement-gravity pumpsAboard vessel most of the pumps are:A. Fixed – most of pumps centrifugal or piston pumps B. Portable – mostly centrifugal-portable electric/normal and submersible/-portable engine-driven pumps-portable eductors

Hydrophore tanks are used in the fresh water system to keep the entire water circuit with the suitable pressure

This 20hp. portable-style pump is based on a vertical 4-cycle, air cooled Yanmar diesel engine with a self-priming centrifugal pump making the YDP20MH capable of pumping a maximum of 500 litres

Portable eductors

•

Portable Foam System

Suction pipesSuction pipes in tanks should be arranged with a bell mouth or foot. The bell end or foot should provide an inlet area of about one-and-a-half times the pipe area. It should also be a sufficient distance from the bottom plating and nearby structure to provide a free suction area, again about one-and-a-half times the pipe area. Suction box have to be regularly cleaned.

Mud boxes

Mud boxes are fitted into the machinery space bilge suction piping. The mud box is a coarse strainer/rough filter/ with a straight tailpipe down to the bilge . To enable the internal perforated plate to be cleaned when necessary, the lid of the mud box is easily removed without disconnecting any pipework.

Bilge system can be used only if there are small holes. For larger holes Bilge system can be used if "Collision Mats" or other materials are used .

Anti Heeling and Trim systems are used to quickly righting the ship in everyday and emergency situations. -Listing the vessel, especially if the damage is near the waterline, will reduce the flow of water into the vessel. This can be achieved by moving weights or ballasting.

The Anti Heeling System enables safe and continuous loading or unloading operations for e.g. container vessel, RoRo carrier, ferries, project carriers, heavy lift and offshore construction vessels in much reduced time. The heeling compensation is automatically achieved by transferring ballast water between the heeling tanks, controlled microcomputer, based on continuous measurement of the heeling angle.

Anti Heeling System

4. Organizational and technical measures for ensuring the seagoing qualities-2 hr

Control and maintenance :-hull of the vessel and watertight bulkheads;-the technical means;-control of loading and stability of the ship ;-training of crew in damage control;-marking of compartments and watertight doors and compliance for their sealing .

The main task is to ensure the strength and tightness of the hull, decks, bulkheads , portholes , watertight doors, hatches , manholes and partition seals .It is Prohibited drilling and cutting holes in the outer shell , decks , watertight bulkheads , covers of manholes and double bottom .Overboard (suction / discharge) and secant valves of ballast and bilge system should be closed.Fire system valves in the cargo holds should be closed

Holds must be always dry, daily measurement of bilges , ballast , fresh water.Monthly must move and lubricate drive units and nuts of watertight covers.Check the condition of all manual actuators for control the valves by manually scrolling.

MANHOLES

For successful damage control, access to any rooms with 2 sets of keys should provide. The first set of keys is kept by the operators of rooms and second kit be kept at ship main panel. Master of ship, Ch.off. and some others senior officers have master keys for certain areas of the ship.

In order to detect latent/hidden defects and places where the water penetrates , the following methods applied:-Light The barrier is illuminated and the other dark part is observed .-Water Strong jet of water is directed to the inspected area. Verification of vertical seams: from the bottom up.-Compressed air Nozzle of air hose moves off to 100 mm ,the other side is coated with a foaming solution . On hollow places bubbles appeared.-Kerosene From one side seam is brushed with kerosene and the other with chalk . On hollow places greasy stains appeared.

Control of Reserve Buoyancy and StabilityCompliance with rules for the adoption and spending loads. Daily monitoring and control of:- Draft- Displacement- Quantity and location of liquid cargo- Initial transverse metacentric height- Heel / clinometer /

5. Fight with flood water -4 hFight with flood water - includes detection of damages in underwater and above-water part of the hull and the places where the water goes .Measures to prevent the spread of water - sealing of leaks, strengthening bulkheads, decks, platforms and waterproof indoor with beams and jacks, pumping overboard of incoming water

By their nature damage to hull can have different shapes and sizes:Small holes to 0,05m2 /inkl. portholes, scuppers, hatches with impaired waterproofing /Average holes to 0,2m2 / intake holes/Large holes to 2m2 / shaft lag hatches, manholes, doors /Many large over 2m2

Crew requires decisive/without doubt/ and quick actions for wrestling with water, detecting the place where water enters, the nature and extent of damage .Duty or watch officer declares/announces emergency alert and report to the Captain.Limiting the distribution of water is an essential step to keep the ship afloat.

Emergency equipment to combat flood water and use it

•Collision mat- a temporary measure that allows to drain the damaged compartment and proceed to reliable blockage. Thanks to its flexibility it assumes the features of the outer surface of the housing.Collision mat Ropes are flexible steel, natural fibers or synthetic fabrics/Nylon, Polypropylene, Polyester/.

Collision mat with netVery strong, metal net, canvas cover

Passage of underkeel ropes is only from the nose when the vessel is underway and from the stern when not running. To reduce the possibility of attaching screws or other obstacles is recommended placing weights at a distance not less than the width of the ship.If the hole is deep to provide false ribs to avoid bending of the Collision Mat in the hole.

Lighten Collision Mat

Solid patches - most effective means for sealing of leaks if the curvature/deformation/ in the hole is small well retain water. Most appropriate for putting in holes near or above the waterline with the help of divers. Heeling or trimming the vessel to reduce flooding.For strengthening of the patches on the holes can be used emergency beams, boards, wedges, plugs, metal jacks, panel clamps, hook bolts, bolts with a mobile bracket.To Use bolts additionally have to drill holes for axis ofbolts.

Solid patch

DAMAGE CONTROL KIT

Damage Control Repair Bags

At the repair locker, small bags made of canvas or other durable material, are neatlypacked with items necessary to make specific repairs that are easily moved to thelocation of need, yet, small enough to be carried to the scene and fit through deckscuttles and hatches with little effort. The following are typical gear bags and thecontents of each kit may vary according to need:1. Investigator’s gear bag2. Electrical repair bag3. Plugging bag4. Pipe-patching bag5. Shoring bag6. Plugging and Patching bag

The two principles for effecting temporary repairs to a hole in the piping system orship’s hull is to:1. Decrease the size of the hole to reduce the flow of liquid or,2. Cover the hole to reduce the flow of liquid

Combat crew with distribution of water in the shipAll watertight structures of ship withstand emergency hydrostatic pressure of water, which is practically possible under the most unfavorable conditions of flooding.As a result of natural wear and tear and as result of accidents the strength of the bulkheads decreases. Therefore if necessary, have to ensure the strength by the adjacent compartments.

Particular attention should be paid to the compartments with large volumes and significant free surfaces. Emergency beams are prepared to strengthen most important waterproof bulkheads.Using diver’s group - Can perform underwater survey for emergency damages, assistance for placing the patch on the hole, as well as emergency activities in flooded ship compartments. Cleaning propeller of wound ropes, contaminated grids of intake holes, etc.

Restore stability and upright damaged shipRestoration of stability - Removal overboard or in the low-lying areas water from compartments located above WL and water from large wide spaces, ballasting the ship, removal overboard of high elevation solid and liquid cargo.Upright damaged ship - Plugging of holes and drying the damaged compartment.Transfer of liquid cargo to compartments of opposite side.Stability is always first. In restoration of stability can be obtained greater heel.