A dry dock is an enclosed dock where a ship is taken for repairs and cleaning of parts of the hull that are normally in the water. When the ship enters the dock, the dock door is closed and then the water in it is drained out by a pump, thus preparing the lower parts of the ship for inspection and repair operations.

Today, most dry docks are designed in such a way that the ship is entered and placed in such a way that as the water gradually recedes, the bottom of the ship is placed on special blocks. The size of the blocks and the distance between them are determined by considering the dimensions of the ship.

When the ship enters the dry dock, it should be positioned vertically and slightly tilted back (trimmed by stern). Then the dock doors are closed and the water inside is pumped out. As the distance between the bottom of the ship and the upper surface of the blocks approaches, the pumping intensity decreases. After the bottom of the ship is placed on the blocks, the other parts of the hull are gradually placed on the blocks towards the stern. When the ship is completely placed on the blocks, the pumping rate of water increases until the basin is completely empty.

The time interval from the bottom of the ship to the time when the last point of the stern rests on the block is known as the critical period. During this time interval, the maximum weight of the ship is placed on the blocks, which may cause risks such as the ship slipping off the block and causing a disaster.

The most expensive and costly figures that commercial shipping companies have to pay on a regular basis are the costs of their repairs and inspections in dry docks. So that a very large cost is incurred in a short period of time. Therefore, strict control must be exercised in the way this operation is carried out. Cost control must be carried out by personnel who are fully familiar with the ship being repaired and its financial issues, which can be done with effective costing methods. The superintendent, who is most involved in repairs and technical issues, must have a logical approach to all stages of repairs, and careful planning in advance is also important, and administrative control in operations is as important as technical operations.

The purpose of taking the ship to the dry dock is to carry out repairs, inspections, and technical maintenance that are impossible to do when the ship is afloat. Usually, even those parts of the repairs and maintenance that are not urgent are replaced, repaired, or any other action that is deemed necessary, in order to make better use of the time and facilities created. Sometimes it is necessary to drydock a ship in less time than the time limit set by the classification societies because of obvious or suspected damage to parts of the hull that are in the water or to the propeller and tail shaft. If the growth of seaweed on the hull and bottom of the ship has significantly affected the speed and fuel consumption, it may be economically viable to drydock the ship for a short period of time. As mentioned, one of the most important aspects of drydock operations is planning and preparation. The most important factor in controlling costs is determining the time required for repairs. A detailed and comprehensive list of all the work to be done during the repairs should be prepared in advance and it is also necessary to obtain firm rates from the repairers for each of the tasks that are expected to be done. A list of mandatory repairs in dry dock (dry docking specification) is required and is prepared by the Supervising Engineer for the ship in question. This list should be based on information extracted from the ship’s monthly defect list and based on inspections carried out by the Supervising Engineer himself with knowledge of the condition and condition of the ship being repaired and obvious and suspected defects that require repair should be recorded. The philosophy of preparing the repair specifications is to anticipate all necessary repairs and determine all information and access to materials related to the work to be done.

The repair specifications should be prepared in a logical order and according to the coded maintenance and repair (dry docking specification) method. After the repair specification list is completed, it should be sent to all ship repair establishments in the area from where the ship is expected to go to dry dock in order to receive the appropriate rate. It is necessary to obtain cost estimates, determine the time required for repairs from all repairers, and evaluate the most economical ones. When selecting a repairer, other factors such as deviation from the ship’s route, the reputation of the repairer, ease of access to technical experts and spare parts while the ship is under repair, and the ship’s subsequent obligations in terms of loading should be considered.

In the case of damage caused by an accident, it must be proven to the insurers that the most fair and economical repairer has been selected for the ship’s repairs. Therefore, records of correspondence before repairs regarding price inquiries should be kept and preserved.

Many of the tasks included in the repair list would be too expensive if carried out by dry dock personnel. Therefore, it is necessary for some of these tasks to be carried out by the ship’s personnel, even if it is necessary to train the personnel for these tasks in some cases.

The ship’s engineer in charge of repairs should try to be present at the repair site at least one day before the ship arrives in order to examine .

From the time the ship enters the repair yard until it is re-entered into commercial service, the sequence of repairs and how they are carried out must be recorded comprehensively and accurately. The recording of the date the ship enters the repair yard is of particular importance. Its particular importance becomes apparent when costs are to be recovered from the insurer as a claim. The important figures of the repairs and their commencement and completion times, especially those parts of the ship’s repairs which are for the account of the shipowner and the costs for which the insurer is responsible and which are carried out simultaneously, must be recorded accurately. After the ship enters the pond and is pumped out, the part of the hull that is submerged should be tested. The steel hull shell (stern frame), rudder blade and propeller, and all underwater parts of the ship should be carefully inspected, especially those parts that are likely to have excessive wear and damage due to collision. Visual inspection of the rudder blade, propeller, and propeller shaft ends should be carried out as soon as possible to allow maximum time for repair and replacement. The condition of the ship’s hull paint, the extent and amount of fouling of the ship’s underwater parts, the condition of the protective anodes, and the degree of clogging of the water intake holes that may be blocked by marine growth should be inspected and recorded for future use. The general condition of the ship at this stage should be considered in relation to the performance of the ship before entering the pond and the necessary decisions should be made to improve its performance. The classification society surveyor also inspects the ship’s hull at this stage and makes the necessary recommendations to keep the ship in-class. Regardless of whether the inspection of the rudder blade or propeller shaft is on the list of repairs or not, the classification society surveyor often pays special attention to them and requests a certificate of their health and absence of defects. If there is damage to the steel plates, the structure of the machinery or any other part of the ship, then the approval of the classification society surveyor and the insurance agent must be obtained regarding the extent and type of repairs.

In the early stages of repairs in the dock, once the extent of the repairs has been determined, comprehensive plans should be drawn up and all aspects of the repairs and inspections should be linked together. In this regard, the classification society surveyors, the repairers and the senior officers of the watch should cooperate. The programme of ship inspections and tank testing should be carefully planned so that the work is not hindered and the ship does not suffer unnecessary delays after refloating. Inspections and tests of holds, loading lines, etc. should be carried out as early as possible so that maximum time can be spent on necessary repairs. Hull cleaning and painting is often one of the major cost items. The purpose of hull cleaning is to remove weeds, scale, rust, old dried paint and oily deposits from the hull. Paint manufacturers usually have representatives in ship repair yards. Paint sales representatives and repairers recommend that large areas of the ship’s hull should be cleaned by sand blasting. Weather conditions have a decisive effect on the results of the cleaning and painting operations. In some cases, after a complete hull painting has been carried out, the ship has left the dock and, despite extensive work being done to prepare the hull for painting, the paint has crumbled due to the painting being carried out in humid weather, which is the result of improper hull preparation.

The daily progress of the work should be closely monitored and if any particular part is found to be behind schedule, steps should be taken to rectify it. Regular meetings should be held with the Supervising Engineer, the repairers’ representative and the ship’s senior officers to monitor the progress of the work. These meetings will improve communication between the parties concerned, clarify issues and prevent delays due to lack of cooperation. It is the Supervising Engineer’s duty to monitor these meetings for brevity and relevance.

The work of sub-contractors should be closely monitored, whether they are employed directly by the main repairer or at the direct request of the ship owner.

. In dry docks, it is almost inevitable that additional work will be required that is not included in the repair specifications. Such repairs can increase the overall cost. Therefore, these costs should be closely monitored. If these repairs are due to damage that was not previously anticipated or to defects discovered during inspection, then there is no alternative but to repair them. The Supervising Engineer should try to keep costs to a minimum while maintaining reasonable standards.

When a ship is in dry dock, special safety measures should be taken, especially against fire, which is one of the most important issues to consider. When a ship is in the dock or even at a repair pier, a considerable amount of welding work may be carried out during that time. Not only is the risk of starting a fire increased by such work, but the risk of fire is also increased due to the general disruption to the ship’s daily operations and the possibility of the fire-fighting system being cut off. The repairers should provide an effective fire-fighting service, but the ship’s personnel themselves should also take precautions and take precautions to prevent fires.

If the repairer’s safety measures are considered adequate, special care should be taken in this regard. The most dangerous areas are those where hot work is carried out around combustible materials and close to fuel tanks. From this point of view, the engine room is one of the most dangerous areas. Almost inevitably, oil and fuel fumes are dispersed and released in the engine room due to the opening of the pipe system and valves. Every effort should be made to prevent oil from accumulating around the machinery. When the ship is practically in dry dock, fire water should be available in sufficient quantity and at the right pressure in all areas at all times. The Superintendent Engineer and the Master should coordinate with the repairer regarding the timing of “hot work” and be prepared in advance to provide firefighting equipment and services. The participation of the ship’s personnel in dry dock repair work is mandatory. Deck officers should be employed to supervise the cleaning of the hull and painting operations, the handling of materials used, the quality of work and the handling of items such as the installation of anodes. Engineers should be assigned to take turns in handling machinery repairs. In particular, Nart assigned them to repair items such as SHIPSIDE VALVES.

As soon as repairs are completed on any machine or machinery, it should be tested immediately to allow maximum time for correction of defects. This is especially true for systems such as the stern gland sealing lubrication, the generator motors and the main engine circulating system.

Any bunker testing in connection with the survey work should be carried out after the ship has been floated, as this will provide sufficient water to fill the bunkers. This will also help to reduce the weight distribution of the ship. Another purpose of this is to reduce the time the ship spends in the repair dock after the ship has been floated. While the tests are being carried out, the machinery can be put back into service or the repairs can be completed. Furthermore, the longer the ship stays in the repair dock after the ship has been floated, the more items of minor repairs and additional work will be required.