DRYDOCKING 101

DRYDOCKING ACCIDENTS/INCIDENTS (A/I)

The study of incident and accident histories is important. One reason is reflected by the old adage, “He who does not study history is condemned to repeat it.”

A good knowledge of the history of drydocking A/I should be used to develop procedures and rules for your dry docks. Knowledge of A/I history is of particular value to the Dock Master in the training of his/her dry dock crew.

It is difficult to obtain information regarding drydocking A/I. Very often, A/I are the subject of litigation with major financial considerations to be determined. Additionally, the reputation of corporations and of individuals involved is at stake. As a result, information is often held quite closely and rarely shared with others.

It would be valuable for the Dock Master to prepare his own file of docking A/I. The file could begin with those listed in this section. As reports of other A/I become available, the facts involved should be collected and made a part of the file.

From personal experience, and from discussions with other Dock Masters and ex-Dock Masters, it is apparent that the Dock Master should also try to obtain as much information as he can about “near misses”. Sometimes operations are conducted unknowingly at the very edge of disaster. Perhaps an unusual ship or an unusual circumstance, not envisioned in planning, makes a standard operating practice dangerous. An alert member of the docking team perceives the danger, corrective action is taken, and a “routine” drydocking or undocking is completed safely. However, if the hazard is one not contemplated by present regulations and practices, it should be highlighted so as to improve the safety of all drydocking operations. A “near miss”, well used, is a fortunate event.

The A/I depicted in below were not the result of haphazard attempts by someone to perform a drydocking, but were carried out by dedicated personnel with the best intentions in mind. However, in each scenario there is clearly an instance in time when inattention to detail, failure to properly communicate, or the lack of a total understanding of the situation at hand; resulted in some type of A/I.

Personnel error is the number one cause of A/I, with material failure a close second. Listed below are copies of some A/I Summary Reports. It is advisable that each activity’s management use these A/I in the training of their dry dock personnel, establishing procedures, and performing required maintenance. Continuous training, updating procedures, and proper maintenance are a must for any shipyard. If complacency sets in, the number of A/I will continue to climb. We cannot afford a catastrophic failure in any drydocking facility. 

 Thousands of drydockings are routinely carried out each year. That singular case in which an accident or incident occurs highlights and illuminates the need for exact and proper drydocking practices. The study of such incidents is an important part of the education of a Dock Master.

A/I SUMMARY REPORTS

(1) A graving dry dock experiences slight flooding during a routine test of the high water alarm as a result of the alarm being de-energized. Upon discovery of water rising through the drainage grates, the drainage pumps were restarted and the dry dock sump was pumped down to normal level. No damage occurred to any personnel, equipment, or the ship in the dry dock.

CAUSE: Personnel error, non-compliance with written procedures for conducting tests.

(2) During mooring repairs, a floating dry dock suffered damage as a result of mooring lines and cables parting and a mooring cleat being ripped from a dolphin due to high wind conditions. The A/I resulted in damage to the dry dock and mooring dolphins. There was no injury to any personnel and the dry dock was unburdened during the incident.

CAUSES: Material failure and personnel error.

(3) On a floating dry dock, damage occurred to a ship’s propeller during an undocking evolution as a result of hitting a side block that wasn’t hauled out properly. Damage to the ship exceeded $50K. No damage to the dry dock or personnel injury occurred.

CAUSE: Personnel error.

(4) A ship sustained damage during an undocking evolution in a floating dry dock as a result of a fouled line, causing the ship to drift to starboard and make contact with the mooring rail on the dry dock. Due to a problem with the radios, the drift could not be stopped. While the ship was resting against the wing wall, radio contact was re-established and the port winch station was directed to winch the ship to port. When the ship was centered, the tugboats made up to the ship and undocking proceeded without further incident. Damage assessment was not included in the initial report.

CAUSE: Personnel error.

(5) A submarine in a graving dock received approximately 1,000 gallons of salt-water spray through a bow compartment hatch when a 4-inch salt-water fiberglass line in the dock separated.

CAUSE: A pipe joint failed because of improper adhesive bonding between the fiberglass pipe and the fiberglass flange. In addition, it was determined that the service outlet manifold was unsupported and applied an excessive load on the pipe, thereby contributing to the failure.

(6) While a submarine was undergoing overhaul in a graving dry dock, the shipyard experienced a system-wide power outage. All dry dock pumping stations were incapacitated, in addition to the telephone, power plant, base radio station, and dry dock high water alarm. Maximum height of water above flood grate was two inches. An emergency gasoline pump (1,000 gpm) was delivered to the dry dock. However, before the emergency pump could be used, normal power was restored and water was removed.

CAUSE: Shipyard-wide temporary loss of commercial electrical power and inadequate casualty control plans covering power outages. 

(7) During a flooding operation in preparation for a submarine undocking in a graving dry dock, a failure occurred at a valve operator for a flood sluice gate. Internal inspection revealed that the final drive worm screw shaft had sheared. Attempts to secure flooding by lowering the stop log failed because in-rushing seawater pressure was great enough to overcome the weight of the stop log, thereby preventing it from sliding into its lowered position. Running two main dewatering pumps at full capacity and one at 25% capacity eventually controlled the water level in the dry dock. The flooding operation was successfully completed by cycling the three dewatering pumps, controlling flood rates and dry dock water levels.

CAUSE: The valve operator work drive shaft failed due to a sharp notch radius that was designed and machined in the shaft at a high stress point by the manufacturer.

(8) While an aircraft carrier was in dry dock, approximately 18 inches of ship’s overboard saltwater discharge accumulated on the floor of the graving dock because a deteriorated fuse holder in the electrical shore power system caused the automatic protective features of the motor controller to trip the pump out of service.

CAUSE: A 12-KV fuse cut-out at a substation failed as a result of deterioration, disrupting power to a dry dock drainage pump. In addition, the back-up generator did not start automatically and provide power to the pumps because the controls were in the “off” rather than the “auto” position. The back-up generator controls were not in the proper position due to inadequate operating procedures and operator training.

(9) While a ship was in a graving dry dock, approximately 1700 gallons of water accumulated on the floor of the dry dock because an automatic water level control system failed to start the dry dock drainage pumps.

CAUSE: Moisture or foreign material clogged the pneumatic portion of the water level control system causing an erroneous water level reading. The control switches for automatic operation of the drainage pumps and a single switch to activate the high level alarm are incorporated in the water level indicator instrument. As a result of the clogged pneumatic system, the automatic water level control failed to start the drainage pumps and the alarm failed to operate and alert dry dock personnel that water was rising in the dry dock.

(10) While dewatering a graving dry dock following an undocking, the dry dock service altars flooded at high tide, allowing water to flow through electrical ducts to the dry dock pump house and transformer vault.

CAUSE: The crew failed to close the malfunctioning altar drain valves. During high tide the service altars flooded through the malfunctioning altar drain valves, and water flowed from the service altar through poorly sealed electrical conduit and ducts to the dry dock pump house and transformer vault.

(11) While a submarine was undergoing overhaul in a graving dry dock, approximately eight inches of water accumulated on the floor of the dry dock.

Primary Causes: (Personnel and procedures) – Improper pump house valve line-up. The suction valve for the affected dry dock and an adjacent dry dock were left partially open, allowing water from the adjacent dry dock sluice tunnel to pass through a pump house suction chamber into the affected graving dry dock. 

Corrective Actions:

1. The qualifications of all dry dock operators were reviewed.
2. The dry dock personnel qualification criteria were reviewed.
3. The dry dock training syllabus was reviewed.
4. A system was established to periodically validate the dry dock qualifications of supervisors and operators to ensure retention of skills.
5. All known dry dock deficiencies were identified and a corrective action plan was prepared.
6. A written plan was prepared to review, update, and automate dry dock procedures; which ensures up-to-date procedures based on the actual condition of the dry docks.

(12) While a submarine was undergoing overhaul in a graving dry dock, approximately six inches of water accumulated on the floor of the dry dock.

Primary Cause: (Design and material) – Electrical power to the automatic drainage pump was lost for approximately 45 minutes when a fuse blew.

Corrective Action: A loss of power alarm was installed to provide a warning when the high water alarm does not function due to power outages.

(13) During the flooding of a graving dry dock, while undocking a submarine, approximately one inch of water accumulated on the floor of an adjacent dry dock.

Primary Causes: (Personnel and procedures) – During the flooding of “A” dry dock to undock a submarine, the pumping facility for “B” dry dock was lined up to dewater the “A” dock. This lineup was utilized to achieve a greater pumping capacity, since ongoing construction on “A” dry dock had disabled all but one dewatering pump. In this condition, “B” dry dock was isolated from the undocking evolution in the “A” dry dock by a single valve closure. This lineup required that the residual water drainage pumps in “B” dry dock (normally used in an automatic mode), to be placed in manual operation. Normal dry dock runoff, minor leakage from the sluice gate used as single valve isolation and inattention by dry dock personnel allowed approximately one inch of water to accumulate on a portion of the dry dock floor.

Corrective Actions:

1. The practice of cross-connecting dry docks and pump-wells was suspended pending a review of shipyard dry dock operating procedures.
2. Shipyard dry dock operating procedures were reviewed to determine if additional personnel were required for this dry dock operation.

(14) While performing routine preventive maintenance on a Navy graving dry dock dewatering pump combined discharge sluice gate, it was noted that of the twelve wedging devices used to secure the valve in the shut position had completely broken free from the main frame. In addition, the guide rail assembly that houses the sluice gate was noticeably pulled away from the concrete housing and the gasket between the guide rail assembly and the housing was deflected outward.

Primary Cause: (Personnel and procedures) – The main dewatering pump or floor drainage pump was inadvertently started with the discharge sluice gate in the fully shut position.

Corrective Action: The dry dock operating procedures were modified to prevent any pumps discharging to sea while the discharge sluice gates were in the closed position. The new operating procedures for sea water discharge to sea requires pump operators to verify “open” on the pump console for discharge sluice gates prior to activation.

(15) While a syncrolift was being lowered, it continued to run in the down direction after the stop button was pressed (off position) causing damage to the winch bull gear and pillar block housing.

Primary Cause: (Material) – The electrical contact failed, which allowed the pawl to engage.

Corrective Action: The contact and vertical bull gear were replaced.

(16) There was a flash fire in a commercial barge docked on a marine railway

Primary Cause: Unknown.

Corrective Action: None – Minor damage to the commercial barge and there was no damage to the railway.

(17) The ballast pump diesel engines failed to start on a floating dry dock with a Navy frigate on the dry dock. Investigation revealed engines were drained of hydraulic starting oil and fuel valves were shut off. Also, there was water in the fuel tanks and the control wires were cut to the fuel solenoid and alarm system.

Primary Cause: (Personnel) – Vandalism by unknown persons.

Corrective Actions:

1. New locks were installed on doors to spaces where engines are located.
2. Additional security patrols were added.
3. Additional security patrols are being made on a random basis.

(18) A ballast pump on a floating dry dock seized during the undocking of a Navy frigate.

Primary Cause: (Personnel and procedures) – The dry dock was set hard on the harbor rocky bottom to achieve the desired draft over the docking blocks. Investigation revealed that bottom frames and shell plating in the dry dock were pushed up and the pump foundation was displaced, causing the pump casing to crack.

Corrective Actions:

1. Retrained personnel.
2. Established new procedures to ensure the dry dock was not set on the bottom.
3. Repaired pump.

(19) During the drydocking of a ship on a floating dry dock, a mooring jammed causing damage to the mooring system and shell plating.

Primary Cause: (Personnel and procedures) – Excessive list and trim of the dry dock

Corrective Actions:

1. Retrained personnel.
2. Established new procedures to ensure the dry dock is operated within operational limitations.
3. Repaired mooring system and shell plating.

(20) During the transfer of a ship from shore to a floating dry dock, a ballast tank was over-pressurized causing damage to a wing wall bulkhead.

Primary Cause: (Material) – The computer controlling tide-compensating pumps malfunctioned.  

Corrective Actions:

1. Repaired damaged wing wall bulkhead.
2. The tide control system will be utilized only when the facility is being used as a transfer facility
3. As an added safety feature, a limit of 36 feet has been established for the tide control tank levels. Beyond this point, tank levels will be adjusted manually.

(21) The pontoon deck of one end of a floating dry dock was found submerged during a routine inspection by security personnel during the night.

Primary Cause: Unable to determine.

Possible Causes:

1. Flood valves were not closed properly after undocking.
2. Deliberate opening of flood valves by unidentified personnel.
3. Object jammed in flood valve.

(22) A floating dry dock and supporting facilities were damaged.

Primary Cause: A ship collided with the floating dry dock after losing steering.

Corrective Action: The dry dock and supporting facilities were repaired.

(23) There was a fire on a commercial tug that was dry docked with a Navy frigate in a floating dry dock.

Primary Cause: (Personnel and procedures) – The fire was started by hot slag from a cutting operation igniting combustible material after workmen left the area.

Corrective Actions:

1. The fire was extinguished by combined efforts of civilian fire department, shipyard personnel, Navy personnel, Coast Guard personnel, and commercial tugs.
2. Shipyard procedures were changed to require combustible materials to be relocated greater distances from hot work.

(24) The unloaded Section 3 (being used as a working platform) of a 3-Section floating dry dock took on a diagonal list. This list caused the pontoon deck of Section 3 to make contact with the propeller blades of the ship that was dry-docked on Section 2. Contact between the pontoon deck and the propeller blades resulted in no damage to the dry dock and minor damage to the propeller blades located at the 5 o’clock and 7 o’clock positions.

Primary Cause: The cause of the incident was operator error. The dry dock operator stated that he left the control house and all pumps were secure. He further contends that someone must have entered the control house and accidentally activated the pump. Management of the facility did not believe this to be true. Management believed that the operator turned on one pump for a normal trimming evolution, and left control house and immediate vicinity of the dry dock without securing the pump. It was further believed that the primary cause was the fact that the operator left the vicinity of the dry dock; otherwise, the listing condition would have been noticed long before contact was made between the dock basin and the vessel. Thus, the cause of this incident was determined to be human negligence.

ACTION TAKEN OR RECOMMENDATIONS TO PRECLUDE FURTHER INCIDENTS:

Adding alarms, refresher training of dry dock personnel, and restricting dry dock personnel to the immediate vicinity of the dry dock

OPERATING CONDITIONS OF THE DRY DOCK AND/OR SHIP IN THE DRY DOCK OR SHIP BEING DRYDOCKED AND/OR STATUS OF SYSTEM OR COMPONENT AT TIME OF INCIDENT:

The dry dock was fully deballasted as required to maintain the ship on Section 2. Sections 1 and 3 were being used as working platforms and were being maintained at a freeboard that insured adequate clearances of the propeller and sonar dome. The vessel had been in dry dock for over three (3) weeks, with no indication of any abnormal leakage or other problems with any section of the dry dock.

IMMEDIATE TEMPORARY ACTION TAKEN AND RESULTS:

All pumps were shut down and Section 3 was flooded down to 6” freeboard (as directed by the Dock Master). The dry dock was inspected for damage and none was found.

PERMANENT CORRECTIVE ACTION:

1. The dry dock procedures were revised to insure that the dry dock Control House is manned or secured at all times. Additionally, it was mandated that required dry dock personnel are to remain within the immediate area of the dry dock or have a qualified replacement if they are to leave the area.
2. An Audio/visual alarm, consisting of a Reflex Control Unit, is being installed. These units will be situated at the end transverse bulkhead of each section. Once the sensing range has been set and calibrated, if the dry dock does take on an excessive list or trim, audible alarms will sound before the situation can cause any damage or threat to the vessel.
3. All dry dock personnel are undergoing refresher training by the Dock Master. This training will include proper notification of Dock Master when required, and proper response techniques to the newly installed alarm system.

EFFECT ON FACILITY’S CAPABILITY FOR SAFE OPERATION AND CAPACITY:

Since no damage was sustained to the dry dock, or associated equipment, and this incident was caused solely by human error, this incident in no way affects the facility’s capability for safe operation.

AREAS REQUIRING FURTHER EVALUATION:

None

(25) SUMMARY OF INCIDENT: During the undocking of USS ARTHUR W. RADFORD (DD-968), the starboard 3-4 Guam block on an AFDM dry dock failed to haul to the undocking position. Because the hauling chain indicated this block was in the undocking position, the undocking proceeded, causing the NR 3 propeller blade starboard shaft on USS ARTHUR W. RADFORD to come into contact with the Guam block.

Description of Incident:

While undocking USS ARTHUR W. RADFORD, the starboard propeller blade came into contact with the dry dock’s NR 3-4 starboard Guam block, which failed to haul to the undocking position. It is assumed that the starboard propeller dislodged the 3-4 Guam block from the bearer log, trapping the edge of the propeller blade between the Guam block base wood and retaining tab. When repositioning ARTHUR W. RADFORD (DD-968) aft toward SRP, the trapped edge, approximately 8-1/4” piece of the aforementioned propeller blade broke off.

Discussion of Apparent Cause:

Material failure. The outhaul sheave attachment point of the Guam block became detached by what appears to be metal fatigue and wastage, allowing the hauling sheave to move outward toward the wing wall giving the appearance of the positive indication of hauling by visually sighting the hauling chain marking points.

OPERATING CONDITIONS OF THE DRY DOCK AND/OR SHIP IN THE DRY DOCK OR SHIP BEING DRYDOCKED AND/OR STATUS OF SYSTEM OR COMPONENT AT TIME OF INCIDENT:

The dry dock was in full operational condition at the time of the incident with certification rated at 13,500 LT. The ship in dock was fully operational with one SSTG on the line to maintain firefighting capability and provide necessary cooling water to equipment. The ship was made up to the dry dock with 6 lines port and starboard, 4 grip hoists starboard, 3 grip hoists port and 1 tug made up to the bow to keep the bow fair to the dry dock.

IMMEDIATE TEMPORARY CORRECTIVE ACTION TAKEN AND RESULTS:

The starboard Guam block has been repositioned on the bearer logs, re-secured and temporarily placed out of service until repairs to the outhaul sheave have been affected. Full operational capabilities of the 3-4 starboard Guam block were restored after completion of the necessary repairs and testing.

PERMANENT CORRECTIVE ACTION:

All Guam block outhaul and inhaul sheaves are to be visually inspected and suspected faulty materials repaired until operation commitments facilitate the coordination of having all outhaul and inhaul sheaves being subjected to Non-Destructive Testing.

EFFECT ON FACILITY’S CAPABILITY FOR SAFE OPERATION AND CAPACITY:

Initial visual inspection indicates 10 of 13 starboard and 3 of 13 port Guam block hauling sheaves are suspected to be near failure due to metal fatigue and wastage. Strongly recommend that all future use of the dry dock be suspended until further inspection and repairs have been affected.

ACTIONS TAKEN OR RECOMMENDATIONS TO PRECLUDE FUTURE INCIDENTS:

Dock Master will visually inspect each outhaul and inhaul sheave for material deficiencies and the necessary repairs affected prior to the next scheduled drydocking evolution. Upon completion of final Non-Destructive Testing, the final report will be submitted.

(26) SUMMARY OF INCIDENT: The outboard mooring arm of a commercial Floating Dry Dock (FDD) broke.

DESCRIPTION OF INCIDENT, GENERAL DESIGNATION AND DISCUSSION OF NATURAL AND APPARENT CAUSE:

(Design XXX Material Personnel Procedure ____)

Description of Incident:

The mooring arm securing the floating dry dock to a dolphin broke, allowing the FDD to float away from the dolphin and rotate about the two inboard mooring arms, which were undamaged. The dry dock was further restrained from rotation by the vehicle access ramp between the dry dock and the landside.

Discussion of Apparent Cause:

The arms had been in place about six and on-half years at the time of failure. The combined effect of wind and waves caused constant motion of the dry dock and over time this shock loading on the arm and friction between the arm’s gripper and the dry dock created fatigue which caused the failure.  

OPERATING CONDITIONS OF THE DRY DOCK AND/OR SHIP IN THE DRY DOCK OR SHIP BEING DRYDOCKED AND/OR STATUS OF SYSTEM OR COMPONENT AT TIME OF INCIDENT:

Dry dock and ship (commercial ship) operating conditions were normal at the time of the incident.

IMMEDIATE TEMPORARY CORRECTIVE ACTION TAKEN AND RESULTS:

A tugboat was called to push on the south side of the dry dock to bring the dry dock back to the dolphin. The FDD translation system wire ropes were put out on the north side to secure the dry dock to the pier and the dolphin, the arm was repaired and reinforced where the break occurred, new bearings were put in all three arms, all components of the mooring system were disassembled, inspected and re-installed.

PERMANENT CORRECTIVE ACTION:

The three mooring arms will be replaced by mooring arms with built-in shock absorbing features, requiring less maintenance and improved greasing access between the mooring arm gripper and dry dock.

EFFECT OF FACILITY’S CAPABILITY FOR SAFE OPERATION AND CAPACITY:

The after arms were not inspected or repaired. The dry dock could not be submerged during the repairs.

AREAS REQUIRING FURTHER EVALUATION:

None

ACTIONS TAKEN OR RECOMMENDATIONS TO PRECLUDE FUTURE INCIDENTS:

A new mooring system will be designed and installed that will absorb shock and require less maintenance.

(27) SUMMARY OF INCIDENT: While deballasting a Navy AFDM following landing, the USS BREMERTON (SSN 698) rolled off of the keel blocks on the vessel’s port side, setting on the basin floor with a 17-degree port list in approximately 18 feet of water.

DESCRIPTION OF INCIDENT, GENERAL DESIGNATION AND DISCUSSION OF NATURE AND APPARENT CAUSE:

(Design Material Personnel XXX Procedure ____)

Description of Incident: The Navy AFDM dry dock was drydocking USS BREMERTON for emergent repairs. After the unit had been hauled into the dry dock, landed on the keel blocks and centered, the side blocks were ordered hauled in and reported as verified to the Dock Master. After deballasting the dry dock to three feet past the landing point, the divers entered the water to verify centering position and block contact on all of the blocks. The dry dock began to deballast ten minutes later, with an inboard draft of 18 feet, the vessel keeled slightly to port and slipped off of the blocks onto the basin floor. It settled with approximately a 17-degree list.

Discussion of Apparent Cause: The cause of the incident was that the dry dock starboard side blocks (port in reference to the vessel) were hauled the wrong way when the order was issued to the Dock Master to “haul in the side blocks”.

The Dock Master did not visually verify satisfactory inhaul of side blocks by observing location of side haul chain indicators. Additionally, the Dock Master neither received nor demanded a positive report concerning the direction of travel or position of the side blocks from the crew member in charge of the starboard wing wall. The diver responsible for checking the dry dock’s starboard side blocks swam the keel blocks instead. A contributing factor was that there were no distinct marks on side blocks or composite keel blocks for identification in low visibility conditions.

As the ship passed through the draft of instability, the ship had some minor heeling moment to port. With no ability to right itself (GM=O), the vessel continued to heel to port and slipped off of the blocks. Dry docking procedures were revised and implemented including all corrective actions. Procedures are in place to preclude recurrence of this type of accident. All critical dry docking stations have formal qualification procedures.

The divers were retrained and their procedures revised to ensure that all blocks are verified in the proper position and condition. Identification markers were installed on keel and side blocks to aid divers in reduced visibility conditions. A formal qualification card is in place for divers performing dry dock diving evolutions.

ACTIONS TAKEN OR RECOMMENDATIONS TO PRECLUDE FUTURE INCIDENTS: Procedures have been revised which provide for positive, two-person verification of side block position. An additional procedure has been implemented that will render it impossible to haul the side blocks the wrong way.

(28) SUMMARY OF INCIDENT: After performing service diesel operational testing on a Navy AFDM dry dock, the port pump room high bilge alarm sounded. Upon investigation, a crewmember discovered swirling, rising water in the pump room.

DESCRIPTION OF INCIDENT, GENERAL DESIGNATION AND DISCUSSION OF NATURE AND APPARENT CAUSE:

(Design Material Personnel XXX Procedure XXX )

Description of Incident: Personnel were operating the dry dock’s service emergency diesel generator for testing under 100% load. After the dieseling evolution was completed, the Fire Main system was realigned for normal operation. Flooding was discovered approximately 30 minutes after restoration of the Fire Main system alignment. Shutting all Fire Main sources into the pump room isolated flooding.

Discussion of Apparent Cause: The source of flooding was determined to be from the pump casing of the number 4 fire pump. The suction valve to number 4 fire pump, which had been red-tagged shut (danger tagged), was found to be open. The exact cause of opening number 4 fire pump suction valve is unknown.

OPERATING CONDITIONS OF THE DRY DOCK AND/OR SHIP IN THE DRY DOCK OR SHIP BEING DRYDOCKED AND/OR STATUS OF SYSTEM OR COMPONENT AT TIME OF INCIDENT: The dry dock was at a freeboard of 3 feet with a submarine in dry dock. Number 1 fire pump was supplying fire fighting capability; number 2 was in stand-by. Number 4 fire pump was partially disassembled with single-valve protection from sea and not isolated with a blank-flange.

IMMEDIATE TEMPORARY CORRECTIVE ACTION TAKEN AND RESULTS:

The flooding was isolated by shutting the sea-chest isolation valve, and suction valves for numbers 2 and 4 fire pumps (establishing two-valve protection). Additionally, the firemain cross-connect valve was temporarily shut.

PERMANENT CORRECTIVE ACTION: Permanent corrective action to be determined pending investigation results.

EFFECT ON FACILITY’S CAPABILITY FOR SAFE OPERATION AND CAPACITY: Fire fighting capability reduced to 50 percent of normal capacity. No impact on vessel in dry dock. (29) A floating dry dock had ballast tank structure collapse while drydocking a ship. Damage was made much worse when the ship was undocked. A sizable portion of the dry dock had to be re-built.

(30) A floating dry dock experienced severe damage to its pontoon deck while drydocking a ship. The aft blocks did not support the ship, which overloaded the pontoon deck of the dry dock. About 90 percent of the dry dock had to be re-built.

(31) A marine railway had all the docking blocks collapse while attempting to dry dock a ship. The docking blocks should have been cribbed together to keep them stable.

(32) A floating dry dock aborted the drydocking of a ship due to leaking ballast valves and other delays. The ship was successfully drydocked the next day.

(33) A floating dry dock was used to dry dock a ship and discovered the forward end of the ship was 23 inches off centerline to port while the aft end was 14 inches to Starboard. The ship was successfully re-docked.

(34) A floating dry dock had to abort an undocking due to several delays and a falling tide. When the undocking re-commenced the next day, the dry dock’s fendering barge hung on the dry dock’s wood fender and rotated, forcing the ship out of position. This caused a scrape in the sonar dome requiring the ship to be drydocked again.

(35) A graving dry dock experienced six inches of water on the dock floor with a ship in the dry dock. The problem was caused by water leaking from a packing gland onto the pilot switch solenoid. The watertight cover was loose and the solenoid shorted-out, causing the circuit breaker to trip. This also shorted the high water alarm that is on the same circuit. In addition, the independent backup high water alarm did not sound because the batteries were dead.

(36) A floating dry dock was drydocking a ship and the ship contacted the forward corner of the dry dock’s wing wall, causing a crack in the ship’s hull. While undocking, they incorrectly hauled two sets of side blocks inboard vice outboard.

1. CLOSING REMARKS

Review of a course of this variety and complexity is a very individual process. One prospective Dock Master may be concerned with the calculations of ship stability as the dry dock water is removed, another may have more concern about his knowledge of dry dock systems.

Each student should take this opportunity to review the chapters of this course, identify areas that are cause for concern or where there remains some doubt about the specific procedures, calculations or techniques that are to be followed in the drydocking process. These areas should be discussed during this final review session.