When we talk about a ship going into drydock, it’s not just about blasting the hull and changing a coat of paint. It’s a highly structured overhaul of the vessel from keel to mast — involving hull, machinery, tanks, hydraulics, electricals, lifesaving systems, and more. The drydock scope is the detailed blueprint of every job to be done during the yard period.
In this blog, let’s dive deep into what makes up a drydock scope, covering the actual checklist from a real bulk carrier’s drydocking — modified to protect its identity. This is as real and detailed as it gets.
General Services and Preliminary Works
Bottom Plugs: All water ballast tank drain plugs are opened, vacuum tested, and re-sealed with cement.
Rope Guard: Removed and refitted, rope cutters and aluminium anodes renewed if required.
Tank Cleaning: Includes sludge tank, bilge sludge tank, HFO settling/service tanks, LSFO tanks, and FO overflow tank.
Hull Paint Markings: Logos, emblems, mascots, and insignia cleaned, re-painted.
Hull Coating and Steel Work
Blasting & Coating: Spot blasting and touch-up coating done across topside, boot top, vertical sides, and flat bottom — all based on visual inspection and coating breakdown.
Sea Chest & Gratings:
Cleaning, high-pressure washing, anode renewal.
Strainers opened and re-coated.
Cargo Holds:
Rusted areas blasted, touched up, and recoated.
Tank top de-rusted.
Steel renewals done where ladders, sounding pipes, or guards are damaged.
Anchor and Mooring Equipment
Anchor Chain: Ranged, high-pressure washed, calibrated, and marked.
Windlass & Winches:
Motors overhauled, brake linings renewed, drums de-rusted, new lock nuts installed.
Hydraulic lines cleaned, painted, and protected against corrosion.
Tanks and Compartments
Chain Locker:
Cleaned, de-rusted, painted up to 1-man height.
Bilge line air-blown through.
Ballast Tanks:
Steel renewals carried out after close-up inspection if required.
Hatch Covers and Deck Fittings
Rubber Packing: All four sides replaced; corners renewed where worn.
Hydraulics:
Leaky cylinders overhauled, seals changed, piston rods re-chromed if needed.
Hydraulic pipes de-rusted, cleaned, and Teflon separators installed.
Structure & Accessories:
Underside/topside corroded areas recoated.
Broken rollers, locking pads, ladders, and stoppers repaired.
Hose test carried out by crew post-repair.
Watertight Integrity
Manhole Covers: 30 units opened/closed, gaskets and bolts replaced if necessary.
Watertight & Weathertight Doors:
Rubber renewed.
Damaged hinges, dogs, springs, and handles replaced.
Eyebrows (drain protection angles) welded above doors.
Deck Fittings & Pipework
Sounding Pipes & Caps: Threads wasted on upper deck pipes renewed (approx. 20 sets).
Log Stanchions: Hydro-blasted and painted.
Pilot and Gangway Ladders:
Wires renewed.
Load tested.
Platforms realigned, sheaves overhauled.
Deck Cranes and Lifting Gear
Cranes:
Motor overhauls, bearing renewals, sheave free-up, corrosion removal.
Luffing and hoisting wires replaced.
Crane structure repainted.
Rudder, Steering & Propulsion
Rudder: Pintle clearance checked, bottom plug opened.
Steering Motors: Overhauled both No.1 and No.2 motors.
Propeller & Shaft:
Super polishing, dye check of blade roots.
Tail shaft and intermediate bearing inspected.
Stern tube seals (Fwd & Aft) replaced.
Lifesaving Appliances
Lifeboats & Davits:
Removed ashore for 5-yearly inspection and load test.
Davit staging erected, sheaves overhauled.
Lifeboats polished and painted.
HVAC and Ventilation
AHU Motor: Overhauled, ducting renewed.
Galley Fan: Fully serviced.
Vent Fans:
Impeller balancing, motor overhaul, damper renewal, casing painted.
Mushroom vents cleaned and painted.
Main Engine Works
Crankshaft: Deflection checked pre- and post-docking.
Unit Overhaul: Crosshead, crank pin, thrust bearing inspections.
Air Cooler: Removed, pressure-tested, cleaned.
Auxiliary Blowers & Pumps: Motors overhauled, balancing tested.
Turbocharger, HPS, OME, AMS: Overhauled by respective service providers.
Jacket Cooling Pumps: Motors overhauled.
Auxiliary Engines
Governors & Turbochargers: All 3 units overhauled.
Air Coolers: Removed, cleaned, tested.
Lube Oil Coolers: Gaskets changed, pressure tested.
Boilers and Valves
Safety Valves & Mountings: Overhauled and tested.
Main/Feed Valves: Pressure tested and reseated.
Boiler Drains, Scum Valves, Blowdown Valves: Cleaned and overhauled.
Sea Water and Piping Systems
Sea Valves:
Overboard and suction valves of all key systems removed, overhauled, and pressure-tested.
Engine Room SW Pipes:
Multiple suction, delivery, bypass, jacket cooling, and condenser lines renewed with detailed flanges and elbows.
Intermediate Valves:
Overhaul of sea water pumps inlet/outlet, central cooler valves, check and stop valves.
Compressed Air System
Main, service, and emergency air compressors — motor overhauls.
Air receivers cleaned and pressure tested.
Safety valves recalibrated.
Steam valves replaced or overhauled.
Atmosphere condenser tubes unclogged, end covers renewed.
Cascade tank cleaned and painted.
Ballast Water Treatment System (BWTS)
Full health check and function test by maker.
Valve actuators overhauled.
Navigation and Electronics (Vendor Scope)
Navigation Systems: Echo sounder, speed log serviced.
ICCP / MGPS: Serviced if found faulty.
WIMS, OMD: Fully tested.
SCBA/EEBD: 5-year hydro testing.
Alternators & ACBs: Cleaned, air gap measured.
Transformers & MSBs: Serviced, tightened.
Pneumatic Control Systems: 5-yearly service.
Final Thoughts
This drydock scope shows how thorough, layered, and interconnected shipyard work is. Every system onboard—from propulsion to paperwork—gets a look-in. If you’re a deck or engine officer heading into dry dock soon, or a superintendent planning your next yard call, study this scope carefully. It can serve as your checklist, roadmap, and inspection aid.
When well-executed, drydocking extends a ship’s operational life, improves efficiency, and ensures safe compliance with class, PSC, and internal standards
