Dry docking and undocking process map

A swimlane map of dry-docking a vessel from block-plan approval to refloat, across the Dock Master, Planning, Mechanical, QA/QC and the vessel/customer. It carries four decision points because dry-docking is the one procedure in a yard where getting a check wrong can mean structural damage to the vessel, not just a schedule slip.

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What is in this map

20 steps across 5 swimlanes and 4 phases, with 4 decision points.

Swimlanes (who does the work): Dock Master, Planning, Mechanical, QA/QC and Vessel / customer
Phases (left to right): Dock preparation, Docking, Dry period and Undocking and departure

Why map this process

Every one of this map's four decisions exists because the alternative is checking a box and hoping. The block plan has to match the vessel's actual keel and bilge profile before a single block is positioned; the vessel has to be centered and within trim tolerance before dewatering starts; block landing has to be verified once dry, with a re-flood-and-re-land loop if it is not. A checklist can ask the same three questions, but only the map shows that each is a gate a vessel cannot pass through on the strength of the step before it.

The dry period is where most of the actual repair work happens, and the map deliberately keeps it as one authorize-then-monitor loop rather than expanding into every trade's own work. That is correct: this map's job is to control entry to and exit from the dry dock, not to plan the repairs inside it — that is what the individual repair and inspection maps in this cluster are for.

Every step in the map

This is the spreadsheet behind the diagram. The numbers in “Goes to” are row numbers, which is exactly what the editor’s “Line to” column holds — so you can read the flow here and retype any part of it.

Every step in the Dry docking and undocking (block plan to refloat) process map, in the order the editor numbers them.
#	Step	Shape	Swimlane	Phase	Goes to
1	Docking date confirmed on the dock schedule	Start	Planning	Dock preparation	2
2	Prepare block plan against vessel's docking drawing	Document	Dock Master	Dock preparation	3
3	Block plan matches keel and bilge profile?	Decision	Dock Master	Dock preparation	5 (Yes), 4 (No)
4	Revise block layout with vessel's chief engineer	Process	Dock Master	Dock preparation	3
5	Position keel and bilge blocks in the dock	Process	Mechanical	Docking	6
6	Position vessel over blocks under pilotage	Process	Dock Master	Docking	7
7	Vessel centered and trim within tolerance?	Decision	Dock Master	Docking	9 (Yes), 8 (No)
8	Reposition vessel with tugs and winches	Process	Dock Master	Docking	7
9	Begin controlled dewatering of the dock	Process	Dock Master	Dry period	10
10	Monitor block landing as the waterline drops	Process	Mechanical	Dry period	11
11	Verify vessel stability and block contact once dry	Control	QA/QC	Dry period	12
12	Vessel stable and correctly landed on blocks?	Decision	QA/QC	Dry period	14 (Yes), 13 (No)
13	Re-flood partially and re-land vessel on blocks	Process	Dock Master	Dry period	11
14	Authorize repair teams to enter the dry dock	Approval	Planning	Dry period	15
15	Repair work proceeds through the dry period	Subprocess	Mechanical	Dry period	16
16	All dry-dock work complete and dock clear?	Decision	Planning	Undocking and departure	18 (Yes), 17 (No)
17	Extend dry period and notify customer of revised schedule	Process	Planning	Undocking and departure	15
18	Flood the dock and refloat the vessel	Process	Dock Master	Undocking and departure	19
19	Final underwater checks and customer walk-through	Process	Vessel / customer	Undocking and departure	20
20	Vessel refloated and departs the dry dock	End	Vessel / customer	Undocking and departure	End

The decision points

Every branch in the map, with the label on each outgoing line. These are the questions the process has to be able to answer.

3. Block plan matches *keel and bilge* profile?

Owned by Dock Master · Dock preparation
- Yes → step 5
- No → step 4
7. Vessel centered and *trim* within tolerance?

Owned by Dock Master · Docking
- Yes → step 9
- No → step 8
12. Vessel **stable and correctly landed** on blocks?

Owned by QA/QC · Dry period
- Yes → step 14
- No → step 13
16. **All dry-dock work complete** and dock clear?

Owned by Planning · Undocking and departure
- Yes → step 18
- No → step 17

Notes on specific steps

These notes travel with the map. In the editor they live in the Notes column and appear when you open a box.

2. Prepare block plan against vessel's docking drawing: Built from the vessel's own docking plan, not a generic layout — keel blocks, bilge blocks and any hull penetrations or sea chests that need to clear a block entirely.
9. Begin **controlled dewatering** of the dock: Pumped down in stages, not in one continuous run, so the block landing can be watched and stopped the moment something looks wrong.
15. Repair work proceeds through the dry period: Every discipline's dry-dock-only work — hull, sea valves, propeller, rudder — has to close out here, because none of it is reachable once the dock floods again.

Making it yours

The controlled-dewatering step and its Notes column are where your yard's own procedure differs most from another's: how many stages you pump down in, and what 'monitor block landing' actually means in practice, belongs there rather than as a new row, because it is guidance for the person doing the step, not a separate action. If your dock uses a different verification method for stability, rename the row and keep its two branches — the decision after it is what makes a bad landing correctable rather than something discovered only when the dock reopens.

What to watch out for

Do not merge the block-plan decision with block positioning. One is a paper check against the vessel's docking drawing; the other is physical placement in the dock. Merging them removes the only place a wrong block layout is caught before the vessel is actually sitting on it.
The stability-and-landing decision has a re-flood branch, not just a fail branch. If you draw it as a dead end, the map implies a bad landing means starting the whole dry-docking process over, when the actual response is a partial re-flood and a re-land — a much shorter loop back.
'All dry-dock work complete' has to be a real gate, not a formality. Extending the dry period is the row that protects the customer's schedule commitment from a trade that quietly runs long — deleting it means the map has no honest way to say the dock stayed occupied longer than planned.

Frequently asked questions

Why is there a separate decision for the block plan AND for the vessel being centered?

Because they can fail independently. A correct block plan can still be badly executed if the vessel is not centered and trimmed correctly over it — the blocks can be right and the vessel's position over them can still be wrong. Keeping both as separate decisions is what lets the map show which one actually failed when a docking does not go cleanly.

How do I add a separate step for underwater hull inspection during the dry period?

Give it its own row inside the dry-period phase, in whichever lane owns it — usually Mechanical, or a QA/QC row if it is a formal inspection. Point the 'all dry-dock work complete' check at it as one of the items being verified, so that gate cannot pass without it.

Does this map cover the vessel's own crew's responsibilities during dry-docking?

Only where they intersect the yard's process — the customer walk-through near the end. If your yard needs the vessel's crew to sign off on specific systems before departure, add a decision after that walk-through rather than folding crew sign-off into the yard's own final checks; it is a different party with a different authority to withhold.

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