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DRY DOCKING
Statutory Regulations
Requirement at special survey and is included in the program of periodical hull
surveys.
Docking Surveys:
 Ships under 15 years old - a minimum of 2 surveys in any 5 years period with
an interval not exceeding 3 years between each survey.
 Ships more than 15 years old - 2 yearly intervals with extension up to 21/2
years where suitable high resistance paint applied maybe accepted as 1 or 2
dry-docking.
The ABS insist that a new ship should be docked at frequent intervals during the first
year or two after launching as there is a possibility of mill scale corrosion and
corrosion due to presence of stray current during building. Docking at 3 months
interval with maximum allowance up to 6 months is allowed.
The Lloyds Register of Shipping requires docking examination at 12 months interval,
which cannot be ex.1"ended beyond 24 months under normal circumstances.
Ships using high resistance paint on under water portion and using approved
automatic impressed current cathodic protection, the interval may be extended to 2
½ years, but that is at the discretion of the classification society.
PROCEDURE BEFORE DOCKING
 Information to Dock Manager
A Dockyard manager will need to know in a docking plan copy:
o Vessel dimension
o Position & size of any weights onboard
o Type of the Bow/rise of the floor
o The numbers of Propellers and/or type
o Details of bilge keels, thrusters & fin stabilizers
o Positions of Echo sounder transceivers, -submerged logs, drainage
plugs and sacrificial anodes
o All relevant documents/certificates i.e., Safecons , Safeq, Gl1DSS,
ILL, Class cert' etc.
Docking plan shows the profile, sectional and plan views, the form of the bottom and
location of all appendages, underwater fittings etc. From these the dock Master
plans the spacing of the blocks for support of the vessel so that no damage can
occur to the bottom fittings
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 Work list
Forward a work list to the Dock Manager of all work required. Details may include:
o Blasting & painting
o Whether tail end shaft & propeller are to be removed
o Rudder types & work to be done on rudder
o Plates to be faired or renewed if collision / grounding. damage etc
A repair & maintenance list must be made & a responsible ship staff to be made
conversant with the list before docking, such as the position of sea-chest, ship-side
valves, filters, corrosion anodes etc must be known to him.
Previous dry dock report should be studied and clearances to be measured noted
(ER department).
Ship Stability
Stability calculations should be made ensuring the vessel has an adequate GM there
should be no, or as little as possible, tree surface. Tanks should either be
emptied/pressed up to full. Account should be made of the rise of 'G' when vessel
takes the blocks & an adequate safety margin allowed. GM must remain positive
until she "sues"(touched all along the block). Shifting of masses to higher tanks
leaving a free surface in tanks may cause stability problem due to lower Meta centric
height and this should be avoided or, if imperative, only be done after prior
discussion with the master.
The critical point in dry-docking is reached when the weight of the ship begins to be
taken by the blocks. The center of gravity begins to rise since pressure on the blocks
is equivalent to discharge of the ships weight and if the center of gravity rises above
the meta centre before the bilge blocks are hauled into space, the ship may list over
and slide off the keel blocks. The dock master carefu1Jy observes the drafts/depth of
water during docking to know when the ship weight is just started to be borne by the
blocks and adjust the bilge blocks.
For ships up to 100,000 GRT, a 5-6 % load may be taken by bilge blocks and this
can even go up to 40% for large ships.
Draft & Trim
The dock Master may stipulate the draught and trim required, this would be based on
the declivity (slope) of the dock. Usually the vessel will be trimmed slightly by the
stem to reduce the thrust on the after keel blocks during the docking; if too much
stem trim the vessel may crack her stern frame. If the vessel is to use a floating dock
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the dock can be trimmed to match that of the vessel.
Vessel normally approaches dock with zero list and a slight trim aft - estimated at 1
m/100m run of the vessel. A light ship conditions is desirable; vessel with
loaded/damaged conditions has to be docked with special care and extra
strengthening of keel blocks and bilges blocks.
Moveable weights
All moveable weights should be made fast and equipment such as boats, derricks
cranes, and gangway etc., secured in their seagoing condition.
Bunker and/or Ballast
A minimum of bunker or ballast to be carried. If carriage of bunker is unavoidable, it
should not be carried in tanks due for inspection or survey.
Watertight doors closed.
Tanks & bilges sounded/recorded
A list of soundings of all tanks and bilges before, when vessel is sewed and prior
flooding to take/recorded. and the reading should be the same. A copy to Dock
Master.
All FFA made ready & ISC fixed.
Emergency lighting
Emergency Lighting and generator sets to be tested before docking - incase of shore
power failure
Toilets I water closets locked
Moorings gear
Mooring and towing gear to be checked to ensure that they are in satisfactory
condition.
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Arrangements made at dock
If possible it is advisable for the-ship's staff to visit the dock whilst it is empty to
check that the necessary arrangements are being made and what the securing and
supporting arrangements are. Ensure:
 The blocks and shoring arrangements are suitable
 The keel blocks are flat, strong and sufficient to support the vessel
 Whether bilge blocks are provided
Services provide by shipyard
Check that the shipyard can provide the following essential services:
 Water for the ship's fire line
 Electricity
 Steam
 Compressed air
 Adequate toilet and washroom facilities within reasonable distance
Telephones
 Gangways at each end of the ship
 Daily garbage removal
 Fire patrol & gangway watchman (particularly if crew are not on board)
Supporting the vessel
Before entering the dock have adequate fenders ready, If side shores are to be used
these are usually put in place immediately the vessel takes the blocks fore and aft
and positioned against strength members. Bilge blocks may be remotely operated
hydraulic units. The vessel is lined up using lines from each bow and quarter with
docking bobs (plumb lines) fore and aft used to find when the vessel is in position.
Once the vessel has taken the blocks sound round all tanks to ensure a similar state
when leaving the dock.
If entering with cargo onboard
If the vessel has to be dry-docked with cargo on board e.g. after a collision or
grounding incident, the vessel may be subjected to severe stresses. The dock
manager will require more information than normal. He should be provided with: - .
A docking plan, showing the position of strength, members, drainage plugs etc.
A cargo plan, showing the distribution and weights of cargo, ballast, fuel etc.
A shell extension plan
Extra shores & blocks will be needed to provide extra support for the vessel to
compensate the additional stresses (racking stress) caused by the weight of the
cargo. It may be necessary to leave some water in the dock to above the level of the
ship's bottom platting to provide extra bottom supports.
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Precautions to be taken:
The ship must be upright before entering the dock, if the ship cannot remove a list
following collision etc., then weights should be taken aboard to bring the vessel to
the upright. Cargo liable to shift should be preferably lashed to avoid any shifting in
case of the vessel takes slight list while pumping out water. "
Pressing-up the double bottom tanks particularly those holds, which carry cargo, this
distributes the load concentration.
Avoid local loading.
REPAIR AND DRY-DOCK LIST
A- STANDARD ITEMS
 Hull cleaning, surface preparation painting.
 Inspection & overhaul of anchors and cables, including ranging & marking
 Inspection cleaning & painting of cables locker
 Plugs to be 'taken from all bottoms & peak tank, all sea valves & sea chest to
be inspected overhauled & painted.
 Inspection & overhaul of rudder & propeller.
 Inspection & overhaul & load test of all lifting appliances.
 All tanks, holds, compartments & their closing appliances to be inspected &
overhauled.
 All anode to be inspected, the location & weight/size to be ascertained.
 Serving of scups bottom, "sighting the bottom" to be conducted
B- REPAIR ITEMS.
 Renewal of piping Cargo handling equipment; Hatch closing arrangement;
Bulkhead leaks; Hull structure damage; Replacement of ship's side rail's
 Instrumentation & control equipment refurbishing
 Electric cable
 Heavy weather damage
 Overhaul of fire fighting & LSA
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C- MODIFICATION ITEMS
 FFA, LSA & fire detection system
 New piping & structural arrangement e.g. segregated ballast tanks system
 Conversion/restructuring in order to comply with any new mandatory
equipment requirements.
PROCEDURES ON ENTERING DRY-DOCKING
Note and log times of
 Entered dock
 Dock gate closed
 Pumping out commence
 Touched block aft
 Touched block forward
 Dry dock pumped dry
 Shore supply connected
Sound all tanks/bilges. Recorded & copy to dock master
Draft & him noted.
For loaded ship - (to minimise stresses)
As soon as vessel is sewed:
 Bilge blocks positioned and built up under the side girder
 Breast bilge shores stepped against frames
PROCEDURES 1N DRY-DOCK
Shore connection taken
 Electricity; if ship alternator are running, attention to be paid on all overboard
discharges such as from domestic fridge, AlC plant and generators to prevent
obstruction or starvation due to temporary stoppage or reduction of pressure
of shore water supply
 Water for fire main (use ISC)
 Domestic use water
 Telephone
Ships septic tanks put into use and garbage collection bins placed at various
points on deck.
Use ofhe1mets to be made mandatory
Ship's staff not allowed to work hanging over the side
Portable extinguishers shall be made available at the site of all welding,
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especially adjacent to oil tanks
Cables hoses to be led so as not to obstruct passageway as far as possible.
Propeller must not be turned without informing the dock authorities or only at their
request for work.
No shifting of weights like transfer of oil/water etc., is allowed unless done with
dock authority & Master consultation.
After shut down, all sea valves to be closed and boilers blown down.
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SAFETY PRECAUTION IN DRY-DOCKING
o Safe working practices complied with
o Local safety rules/precautions complied with
o Liaison maintained with dock safety officer
o Provide safe & properly lit means of access to/from vessel.
o Post ship watchman on gangway to prevent unauthorized entry
o Provide proper lighting in all working areas & passage
o Fence off & illuminate all manholes and similar openings
o Entry into enclosed spaces is authorized by a responsible officer & in
accordance with code of safe working practices
o Display notices at appropriate places.
(No Unauthorized Entry Into Enclosed Spaces; No unauthorized Hot Work; No
Smoking; First Aid Kit Located At ... ... ... ...; Instructions In The Event of Fire; ER
Escape Exit; Tunnel Escape Exit)
Keep all FF A ready
Fire hoses with nozzles connected from-shore hydrant to laid on deck with water
mains pressurized through ISC at all time.
Portable Extinguishers, BA sets, Fireman's outfit etc., in readiness for use in
emergency.
Fire Plan copy to Dock-Master
Hot work'
Ensure compliance with checklist such as Gas tree the compartment & adjoining
compartment; obtained gas free cere; Eliminate fire hazards by responsible
officer inspection; fire watch station in adjoining compartment; stdby FF A;
Maintain fire patrol.
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WORK IN DRY DOCK
Shipside Cleaning and Painting.
Hull may be scrubbed and scraped as the water falls, if the dock is pumped out too
quickly the cleaning will be poor. Alternatively, the hull may be cleaned by water jet. If
necessary the hull can be short-blasted before repainting with anti-corrosive and
Anti-fouling paints. Attention to joints underside of bilge keels, previous marks of
bilge & keel blocks etc.
Ensure to put a cover all transducers/receivers, anodes, moving parts, bot_om plugs
holes with grease, polythene sheets or masking tapes before painting.
 Draught Mark, Load line, Ship's Name & Registry Port.
Checked and repainted. It may be convenient to arrange for a Load line survey to be
carried out at the same time
 Sacrificial Anodes.
Will be inspected and renewed where necessary; usually all of them.
 Propeller and Rudder.
The propeller cap will be removed and renewed, propeller nut removed and the
propeller eased out on tackles. Examination lof propeller i.e., checking damage due
to pitting or cavitations corrosion or grounding. Blade thickness for built up
propellers, polishing of blade surface and checking the propeller nut for movement.
The section of propeller shaft forward of collision bulkhead may be removed to allow
the tail end shaft to be withdrawn for inspection by surveyors. Stem tube bearing
wears down taken. Tail end shaft is checked during special survey at interval of 4
years and may be extended to a maximum period of 5 years.
Surveyors will also examine the rudder bearing for wear; the rudder will be drained,
jacked up or slung to examine the wear on the bottom bearings/carrier ring, pintles
and their locking devise. Rudder and tai_ end shaft clearances measured.
 Over-side Discharges and Suctions.
Ail intakes and discharge outlets and underwater valves are examined after being
opened up. Baffles and grilles are removed and their insides cleaned and painted,
the valves will be overhauled.
 Plugs.
If it is necessary to drain any tanks, the plug will be removed, labeled and kept in a
safe place in the care of Chief Officer
 Double bottom tanks etc.
Where possible, double bottom tanks etc., will be cleaned, scraped and recoated. All
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dangerous space precautions should be observed including obtaining gas free
certificates where necessary. Survey of tanks which are due and cleaning of tanks by
removal of drain plugs
 Submerged logs and Transducers
Where required, maintenance should be carried out on submerged logs and echo
sounder transducers
 Anchors and Cable.
Anchors and cables may be ranged on the dock bottom with the links hammer tested
for soundness. Cable size ",ill be measured (lengths with wear> 10% reconditioned
and re-tested or renewed). Joining shackles are opened, greased & reassembled
with new lead pellet. Joining shackle number markings are renewed. The two or
three lengths next to the anchor may be moved to the locker end of the cables
enabling the wear to be equalised - the cable will need to be remarked. If necessary,
the chain locker can be cleaned, scaled and repainted.
 Progress/Completion Inspection is carried out;
o of all work by ship's crew
o of all survey items by Surveyor to the Classification Society.
o Repairs to water-tight structure (hul1Jbulkhead'sideck) are Hose tested
to the surveyors satisfaction
PROCEDURES BEFORE LEAVING DRY-DOCK
Ensure:-
 Items of repair list left unfinished, not satisfactory completed or not done
noted & brought to the intention of company's representatives.
 Check that all plugs are replaced in double bottom, deep and peak tanks and
rudder. The dock manager may require a signed statement that this has been
carried out. .
 Sounding of all tanks and bilges same as after taking the blocks. . Non-return
valves, inlet and discharge pipes are in place, particularly where they have
been removed for overhaul. Gratings and baffles should be replaced with any
nuts being wired to prevent them working loose
 All overboard and sea suctions to be shut
 Sacrificial anodes are not painted and the sea chest is painted with anti-
fouling paints. Masking tape grease remove from echo-sounder transducer.
 The propeller shaft should be replaced, propeller secured and stem tube
sealed.
 Anchors and cables secured.
 The shell plating is intact; any plates removed, holes or rivets missing should
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be sealed or replaced.
 The weight distribution should be the same as when the vessel entered the
dock. Any tanks emptied for repairs are to be filled to their previous level.
 Stability of the vessel to be checked and should be the same as before
entering the dock.
 If mooring lines have been removed then ropes are lead from each bow and
quarter, taken to a winch and left slack. The slack can be taken in and they,
can be tended as the vessel rises when the dock floods.
PROCEDURES BEFORE UNDOCKING
Where all is ready (the moment ship's plant are in operation);
 Disconnect fire line, telephone, electricity, airlines etc.
 Prepare the bridge gear equipment; test & checked as per before entry in
dock
 Take in the gangways
 Personnel to be placed at all vulnerable points on the ship, especially in
engine and steering compartment
 Crew on undocking stations
 If extensive repairs to engine/steering gear are carried out, a dock trial is
recommended.
PROCEDURES DURING LEAVING
Note & record the time of commencement of flooding.
Monitor sounding in dry compartments.
(Stop flooding & investigate if water is found, rectify & pump out & then resume
flooding)
Note and log times of refloating of ships. Note the draft.
ANCHOR AND CABLES
May be ranged in the dock bottom for greasing, testing for wear-down, changing the
cable lengths, remarking, renewal of lead pellets, and at the same time the chain
locker can be cleaned and scaled/coaled if necessary.
ANCHOR & CHAIN CABLES ACT 1967
Anchor included shackles (exclude stock for stocked anchor) to be tested if> 76 kgs.
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Application to test from Classification Society through Mardep.
Tested to a proof tensile strength with varies: 20 X wt for 1 T anchor to 5 X wt for 30T
anchor. Cert' issued 1 month after test which contains:
(1) Serial No
(2) Name & mark of testing establishment
(3) Name & mark of certifying authorities
(4) Name of test supervisor
Also include:
(i) Type of anchor
(ii) Weight in Kg
(iii) Weight of stocks
(iv) Length of shackles in mm
(v) Length in arm
(vi) Showing the diameter of the trend or throat in mm (for common
anchor)
TO RANGE CABLE IN DRY-DOCK
 Walk-back cables until last cable. Range cable along the dock bottom as it
lowers.
 Shackles a 25mm wire to the link near the hawse pipe and turn it onto the
bits.
 Walk-back anchor chain until the wire takes weight, engage bow stopper.
 Clear the area in the dock below and around the hawse pipe.
 Cast the bitter end and adrift in the chain locker.
 Walk-back cables slowly until the bitter end is on the gypsy. Man handles
chain with chain hooks on deck
 Shackles a second wire 25nun to the bitter-end link and lead it to the warping
drum pick up slack
 Surge first easing wire until the gypsy and the second wire take the weight of
the cable.
 Walk-back on the gypsy and the second wire and simultaneously payout on
first wire until bitter end is at dock bottom
 Remove and recover both wires.
When ranged, cables examined for wear & renewed: Approximately 10% wear down
in bar diameter (D) is allowed before replacement is required.
At a Survey:
 Joining shackles opened & all parts examined.
 Will then be cleaned & well lubricated before assembly (warm tallow used for
the bolts & while lead for the spiel pins)
 Every link will be sounded with a hammer to test for a clear ring.
 Loose studs in wrought-iron cable must be re-caulked or replaced
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 Wooden pins are renewed
 Replaced/repaired cables, tested again to its statutory proof load (Cables
benefit from regular heat treatment, but lugless shackles of nickel steel are
exempted).
Note:
 Anchors are not normally re-tested or given further heat treatment after initial
processing unless considered desirable. (The anchors & cables benefit from a
regular coating of Stockholm tar or special chain paint)
 The pivoting mechanism of a stockless anchor should be regularly lubricated
with thick grease
 Cable securing fittings should be thoroughly overhauled
 In use, the lead pellets should be sighted - faulty insertion often leads to their
dropping out of the recess above the spiel pin.
HEAVING-IN CABLE IN DRY-DOCK
 Ensure all shackles have been reconnected & marked.
 Send a 25mm wire down over the gypsy, through. bow stopper & hawse pipe
to the deck & shackle to the bitter end
 Lead wire to a warping drum directly abaft the windlass or tl3.rough a snatch
block to a warping drum of the windlass
 Clear men from the dock area in the vicinity. Take weight on the wire. . Heave
in the wire until the end link is on of the gypsy surge. The first link must pass
over the surge in the vertical position.
 Engage the bow stopper, lash the chain, disconnect the wire, manhandles end
link down spur ling pipe
 Secure end link in the chain locker
 Take weight of chain on the windlass. Release lashing and bow stopper
 Heave in chain. Send man in chain locker to stow chain if necessary
 Do not use chains hooks/blocks.
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