DRY DOCK SURVEY

DOCKING SURVEY ITEMS

SOLAS I/10
Ship’s bottom inspection and duration

■ Bottom/Docking Survey:
■ Two ‘Docking Surveys’ are required to be completed within any 5 year survey cycle.
■ Max period between two successive dockings not to exceed 36 months and one must coincide with Special Survey.
The ‘Intermediate Docking Survey’ may be replaced with an ‘in-water survey’, if the ship meets the in-water survey & IWS notation. (Note: IWS not permitted for ESP ships over 15 years)

The purpose of docking survey is to check some specific items which are submerged in the water or which cannot be checked during service period and also check hull painting. We can divide the survey in two parts:

A) items inspected during dry-docking survey

1. Shell plating (including bottom & bow plating) checked for excessive corrosion, deterioration, unfairness or buckling, special attention to bilge strakes & bilge keels, seachests & gratings, sea connections & overboard discharge valves/ cocks and fastenings
2. Visible parts of rudder, rudder pintles, rudder shafts/ couplings and stern frame, rudder bearing, clearance to be obtained, pressure test of rudder may be required.
– Rudder stock connect at the bottom to the pintle by bolted couplings. Check through inspection holes
– Couplings enable the rudder to be inspected from the pintles for inspection and service.
– Rudder pintles point about which the rudder turns. Ships can have one or more (upper/lower) pintles. Check through inspection holes (upper and lower)
– Rudder bearing weight of rudder carried partly by lower pintles, partly by rudder bearer within the hull
– Pintle bush clearance
– Pintle bush clearance: The clearance between the pintle and the bush (rudder stock lower side) is measured using the thickness gauge. The clearance is taken in four sides: forward, aft, port, and starboard. The measurements are taken through the inspection cover, usually on the port side. The normal clearance is about 1 to 2 mm.
Neck bush clearance
Neck bush clearance: The clearance between the rudder stock and the neck bush (rudder stock upper side) is measured using the thickness gauge. The clearance is taken in four sides: forward, aft, port, and starboard. The measurements are taken from top of the rudder. The normal clearance is about 1 to 2 mm.
Swing test carried out

3. Visible parts of propeller & stern bush. Stern bush clearance & efficiency of stern gland to be determined. CPP fastenings and tightness of hub if fitted.
– Check clearances before removal. Remove cone, remove locking nut, Crack detection on tail shaft – dye penetrant test. Then fix back and check clearance again.
4. Visible parts of side thrusters if fitted
5. Cathodic protection
6. Anchors & chains ranged

B) Hull painting during dry-docking survey
1. underwater hull cleaned of all fouling , barnacles, weeds
2. de-scaling and application of primers, application of anti-fouling paint (precautions with echo-sounder apertures, probes, tank-plugs).
3. wetted surface area of underwater hull obtained by formula: Wetted area (sq.m) = 2.58 x √(light displ.(tonnes) x ship length) (m)