Dry docking and undocking SOP: block plan to refloat
A shipyard SOP for dry docking and undocking a vessel: block plan verification, controlled dewatering, a stability check, dry-period repair work, and refloat, with an owner and workload hours on every step.
What the dry docking and undocking SOP: block plan to refloat process is
A vessel does not settle onto blocks the way it settles into a berth. Every keel and bilge block has to be under a load-bearing point the vessel's own docking drawing specifies, and a block plan copied from the last similar hull, or eyeballed against a general arrangement instead of the actual docking drawing, is how a sea chest or a hull penetration ends up resting on a block that was never meant to carry it. The damage from that mistake does not show up while the dock is still flooded. It shows up as the waterline drops and the vessel's own weight transfers onto whatever is actually underneath it, which is why the process is drawn with a verification decision before a single block is positioned, not after.
The chart carries three decision points for the same reason a dry dock has three places where a docking actually fails: the block plan can be wrong before the vessel ever enters the dock, the vessel can come to rest off-center or out of trim as the water drops, and the landing itself can be wrong once the dock is dry. Each of those is a branch back to rework rather than a note to fix later, because a block plan corrected after the blocks are set, a trim corrected after dewatering has finished, or a landing accepted without a stability check is corrected at far higher cost than the branch that catches it a step earlier. Collapsing any of the three into a single 'dock the vessel' step is exactly the shortcut that turns a routine docking into an unplanned re-float.
The dry period itself is drawn as one authorized step rather than a list of trades, because every discipline working under the hull, sea valves, propeller, rudder, hull coating, is working on borrowed time against the same flood date, and none of that work is reachable once the dock floods again. The People and Workload columns on each row exist to make that borrowed time visible before it runs out: the dock master, the planning lead, the mechanical foreman and QA/QC each carry named hours against their own steps, and a yard running several dockings across its dry docks at once reads that load through the workload BI panel instead of finding out at the dock-clear decision that a step nobody had staffed for was still open.
What this flowchart covers
In this template
- Dock preparation: the block plan is built against the vessel's own docking drawing at "Prepare block plan against vessel's docking drawing", checked at the decision "Block plan matches keel and bilge profile?", and any mismatch routes to "Revise block layout with vessel's chief engineer" before a block is positioned
- Docking: "Position keel and bilge blocks in the dock" and "Position vessel over blocks under pilotage", gated by "Vessel centered and trim within tolerance?" with an out-of-tolerance branch to "Reposition vessel with tugs and winches" before dewatering starts
- Controlled dewatering and the landing check: "Begin controlled dewatering of the dock", "Monitor block landing as the waterline drops" and "Verify vessel stability and block contact once dry", closed out by the decision "Vessel stable and correctly landed on blocks?" with a "Re-flood partially and re-land vessel on blocks" branch if the landing is wrong
- The dry period: work only starts once "Authorize repair teams to enter the dry dock" has been given, and "Repair work proceeds through the dry period" carries every trade's dry-dock-only work through to the dock-clear check
- Undocking and departure: the decision "All dry-dock work complete and dock clear?" branches to "Extend dry period and notify customer of revised schedule" when it is not, and otherwise proceeds through "Flood the dock and refloat the vessel" to "Final underwater checks and customer walk-through"
- Named People and numeric Workload hours on every step, from the Dock Master and Planning lanes through Mechanical and QA/QC to the Vessel / customer lane, so the workload BI panel can total effort by person and by stage across a docking
When to use this template
- You're scheduling a vessel onto the dock calendar and want a controlled, approved sequence the dock master, planning lead and customer are all working from, not a verbal understanding of the order of operations
- A previous docking landed off-center or with a block not taking load correctly, and you need a documented stability check and re-dock branch instead of relying on someone noticing during the dry period
- You're running more than one docking through the yard's dry docks in the same window and need the People and Workload columns to show where the mechanical foreman or QA/QC lead is already committed before you promise a repair slot
- The dry period is regularly extended without a documented reason, and you need the dock-clear decision and its extend-dry-period branch to force a written cause and a revised date to the customer
- You're inducting a new planning coordinator or dock master and need a reference sequence from block plan verification through the final underwater walk-through, rather than tribal knowledge of what happens next
How it works
Match the lanes to your own dock organization
The sample uses Dock Master, Planning, Mechanical, QA/QC and Vessel / customer. If your yard splits mechanical from electrical and hydraulic repair capability, or routes authorization through a separate dock superintendent, give each its own lane rather than folding it into Mechanical: the lane is what tells a reader who owns a step at a glance.
Replace the sample People and Workload values with your own roster and hours
Swap the named people for your actual dock master, planning lead and foremen, and set Workload to the effort each step realistically takes at your yard, not elapsed calendar time. That is what the workload BI panel totals, so placeholder hours produce a placeholder workload picture.
Write your own tolerance and stability criteria onto the decision boxes
"Vessel centered and trim within tolerance?" and "Vessel stable and correctly landed on blocks?" need numbers behind them: the centering and trim tolerance your pilots work to, and what 'correctly landed' means for the hull types you dock. A decision with no stated criterion gets answered by judgement, which is exactly what a re-dock branch exists to catch.
Add your own dry-dock work authorization gate
"Authorize repair teams to enter the dry dock" should name who actually signs it at your yard, whether that is the dock master alone or a joint sign-off with QA/QC, and what the authorization confirms: block landing verified, dock access safe, permits issued.
Extend the dry-period step for your own trade mix
"Repair work proceeds through the dry period" is deliberately one step covering every trade's dry-dock-only work. If you need visibility into hull, sea valve, propeller and rudder work separately, split it into parallel rows in the same stage rather than serializing them, and keep each on its own workload total.
Keep the final customer walk-through as its own step, not a note on refloat
"Final underwater checks and customer walk-through" is the customer's own sign-off before departure. Keeping it as a separate row after "Flood the dock and refloat the vessel" gives you a distinct approval and a distinct owner, rather than bundling customer acceptance into the refloat itself.
Frequently asked questions
Why does this SOP have three separate decision points instead of one docking step?
Because a docking fails at three different moments, not one: the block plan can be wrong before the vessel ever enters the dock, the vessel can settle off-center or out of trim as the water drops, and the landing itself can be wrong once the dock is dry. Each decision is placed at the moment the corresponding mistake becomes checkable, and each branches back to rework rather than forward to a note, because catching a bad block plan before positioning is far cheaper than catching it after the dock is dry.
What do the People and Workload columns do on this chart?
Each step carries the person or people accountable for it and a Workload figure in hours representing the effort that step actually takes, not the calendar time it spans. The workload BI panel reads those two columns across the whole chart to total effort by person and by stage, so a planning lead can see, for example, that the mechanical foreman is already carrying six hours of dry-period work on one docking before committing them to a second.
What happens if the block plan doesn't match the vessel's keel and bilge profile?
The decision "Block plan matches keel and bilge profile?" routes a mismatch to "Revise block layout with vessel's chief engineer" and back to the same check, rather than letting positioning start on an unverified plan. Blocks are physically positioned only after the plan passes this check, which is what keeps a hull penetration or sea chest from ending up resting on a block it was never designed to carry.
Who authorizes entry to the dry dock, and who authorizes undocking?
They're separate gates with separate owners on this chart. "Authorize repair teams to enter the dry dock" opens the repair period once the vessel is confirmed stable and correctly landed. "All dry-dock work complete and dock clear?" is the later, separate gate that decides whether undocking can begin, and it branches to "Extend dry period and notify customer of revised schedule" when work isn't finished rather than letting flooding start on an incomplete dock.
Can this SOP be adapted for a floating dock or a syncrolift instead of a graving dock?
Yes, the stage structure carries over: block plan, positioning, controlled dewatering (or lift) with a landing check, an authorized work period, and a dock-clear decision before returning the vessel to the water. What changes is the mechanics inside a few steps, positioning blocks on a floating dock's pontoon deck or setting a syncrolift's transfer sequence, so revise those specific rows rather than the overall sequence.
Where this process fits
In most operations this process follows Vessel arrival and docking SOP (ship-repair yard) and hands off to Ship repair project kickoff SOP: specification to work packages.
It is one step in Ship repair.
Step 1: Vessel arrival and docking SOP (ship-repair yard)
A vessel arrival and docking SOP for a ship-repair yard: pre-arrival berth checks, pilot and tug booking, the weather and tidal go or hold decision, pilotage, mooring, and a signed handover to the project team.
Step 2: Dry docking and undocking SOP: block plan to refloat You are here
A shipyard SOP for dry docking and undocking a vessel: block plan verification, controlled dewatering, a stability check, dry-period repair work, and refloat, with an owner and workload hours on every step.
Step 3: Ship repair project kickoff SOP: specification to work packages
A ship repair project kickoff SOP: specification intake, mechanical/electrical/hydraulic review, PM assignment, work-package breakdown, subcontractor gap-fill, scheduling, and a confirm/revise kickoff before work reaches the workshops.
Step 4: Shipyard subcontractor onboarding SOP: induction to checkout
Step 6: Vessel repair handover SOP: completion review to departure