TOPIC FOUR: DRYDOCKING, PORT OF REFUGE, AND SAFEGUARDING CARGO 4.1. Dry-docking

Question 1

(a) State particulars to be provided to dock master and records of previous dry-dock

Answer 1

a) ETA and ETD of intended dry-dock.
b) The principle dimensions of the vessel.
c) Vessels Docking Plans.
d) Previous dry-docking data with position of echo
sounder transducer, any keel penetrations and the
position of the docking blocks from the previous
docking..
e) Specimen calculation of the ships ideal docking
condition, obtained referencing the ships stability
book.
f) A calculation of the ships intended dry-docking
condition.
g) Drafts and trim.
h) Weight distribution of the vessel.
i) Any structural or hull damage including propellers
and rudder.
j) Positions of any external hull fittings.
k) Any other relevant data which may affect the
docking.

Question 2

(b) State the optimum conditions for dry-docking

Answer 2

a) The vessel should be upright.
b) The vessel should be trimmed slightly by the stern.
c) The trim should not be excessive to reduce the
critical period and upthrust.
d) Initial KG should be large to ensure a positive GM
throughout the critical period.
e) Free surface effect should be eliminated in tanks as
far as possible.
f) The ship should have a shallow draft to ensure a
good KM.
g) All weights onboard should be distributed evenly.
h) All loose weights and cargo should be secured.
i) The actual draft and trim should be as near as
possible to the condition supplied to the Docking
Master prior to the dry-docking.

Question 3

(c) State the precautions to be taken in dry-dock

Answer 3

♣ Obtain and record soundings of all tanks and their
weights.
♣ Couple the fire mains to shore-side supply.
♣ Ensure safety equipment that may be damaged
during repairs is safely stowed and locked away.
♣ Delegate a Muster Point ashore in the event of an
emergency.
♣ Obtain relevant Emergency Contact Details such as
Fire Brigade, Ambulance and Dock Master.
♣ Ensure the gangway is safely rigged at all times.
♣ Arrange for garbage skips for the duration of the
docking.
♣ Arrange shore-side ablutions for ships staff if
required.
♣ Ensure a bonding wire is connected to shore power
(prevents build-up of static electricity).
♣ The Permit to Work system must be agreed upon,
and any work requiring a permit must not be started
until the relevant permit has been issued.
♣ A running list of all open tanks and any docking
plugs removed must be kept.
♣ A running list of ongoing work must be kept.
♣ Security of the vessel must be maintained at all
times, with any stores or spaces not requiring
access for repairs to be locked.

Question 4

(d) State the precautions to be taken before undocking

Answer 4

♣ Find out rate at which dock is able to supply ballast
and fresh water to calculate the time needed to refill
tanks that have been emptied to their pre-docking
condition.
♣ Ensure tanks are filled to their original status and
not over-filled.
♣ Stability should be re-calculated and weight
distribution compared to the pre-docking condition.
Inform the Dock Master of any changes to trim,
drafts or stability.
♣ Check that all docking plugs have been replaced
and are secure.
♣ Check all tank lids are replaced and secure.
♣ Check the sea suction gratings are secure and that
the bolts have securing wire threaded through them.
♣ Remove grease from transducers and house anchors.
♣ Engineers to check all overboard non-return valves
are in place and secure.
♣ Ensure all rigging used for work on the rudder and
propeller is removed.

Question 5

(e) State the precautions to be taken during undocking

Answer 5

♣ Sufficient mooring lines secured to dock.
♣ Sound all tanks, voids, coffer dams, chain lockers
and holds to ensure there has been no water ingress.
♣ Engineers to check all non-return overboard valves
and the stern seal.
♣ Dock Master to check drafts.

Question 6

(f) State the specific precautions to be taken when dry-docking with a full or partial cargo

Answer 6

♣. Inform Dock Master of position, weight and nature
of the cargo onboard, in order that extra docking
blocks can be placed beneath these areas of
additional stress.
♣ Fill Double Bottom tanks below the areas containing
cargo to evenly distribute the load and prevent
localized stressing.
♣. Divers may be utilized to ensure the vessel lands
safely on the blocks and to check if any blocks will
need to be moved.
♣ Extra shoring may need to be arranged to support
the vessel.
♣ Ensure cargo areas are secure at all times.