At a properly resourced Indonesian yard, hull replating progresses at roughly 1–3 tonnes of steel per day per working front — so a 20-tonne renewal typically adds 10–18 working days to a docking, and a 50-tonne special-survey renewal can hold a vessel 3–5 weeks. The spread is wide because replating speed is set less by welding time than by everything around it: gauging decisions, plate logistics, fit-up inspection and class witnessing. Here is how the timeline really builds, and how owners compress it.
Where replating time actually goes
Owners picture cutting and welding; the calendar disagrees. A single renewal cycle runs: mark-out from the gauging report → cut out wasted plate → prepare edges → fit new plate → fit-up inspection before welding → weld → visual and NDT checks → class surveyor witnesses → coat. Welding is perhaps a third of the elapsed time. The rest is decisions and queues: agreeing which plates go (the gauging call), waiting for plate stock or profiles, staging access, and synchronising the surveyor’s visits so completed work is not left waiting for witness. A yard with two or three simultaneous working fronts — bow, midship, stern — multiplies daily output; a yard that starts one front with one crew does not.
Planning numbers by renewal size
| Renewal tonnage | Typical added dock days | Typical context |
|---|---|---|
| Under 5 t | 3–6 days | Local wastage, contact damage |
| 5–20 t | 7–18 days | Ageing coaster at intermediate/special survey |
| 20–50 t | 15–30 days | Older tonnage at special survey |
| Over 50 t | 4–8 weeks | Neglected hulls, conversions, casualty repair |
These are added days on top of the base docking scope, partially overlapping it — washing, inspection and other trades continue in parallel. For how the whole docking calendar assembles around steel, see the cost and duration structure in our USD docking cost guide.
The five factors that stretch or shrink the schedule
Plate availability: standard mild-steel plate in common thicknesses is stocked in the main yard clusters; higher-grade or thick plate may travel from a mill or importer, and a week of waiting erases a week of welding. Lock the material list before docking. Gauging decisiveness: the single biggest schedule saver is a pre-docking gauging campaign, so the renewal list exists before the ship dries out; deciding plate-by-plate in dock serialises everything. Working fronts and welder numbers: ask the yard, in the tender, how many certified welders and simultaneous fronts the job gets — and hold them to it. Class witnessing rhythm: batch completed sections for the surveyor’s visits; a section finished Tuesday that waits until next Monday for witness is five days lost. Internal obstructions: tanks must be gas-freed, framed areas accessed, insulation stripped — discovered late, each becomes its own delay. A disciplined yard-vetting pass, as we describe in the shipyard vetting checklist, screens for all five before the contract is signed.
Quality control that does not slow the job
Speed and quality are not opponents in replating — rework is the real schedule killer. The controls that pay for themselves: fit-up inspection before welding (a gap corrected in fit-up costs minutes; cut out after welding, days), welder certification checks against the procedures actually used, staged NDT on butts and seams rather than one end-of-job campaign, and coating windows planned so fresh steel is primed promptly instead of flash-rusting and needing re-blasting. Our supervisors log every renewal on a plate map with photos — the same map later becomes the remeasure record that keeps the invoice honest, which is where replating projects most often go wrong financially; the wider repair-supervision method is described in our ship repair guide.
After redelivery, warranty follow-up on renewed plating — coating touch-ups, weld checks at first docking — can be routed through the group’s specialist hull and boat repair desk so the replating record stays with one team.
Ballast tanks: the hidden half of steel time
Much Indonesian renewal work lives inside ballast tanks, where coatings failed years earlier and framing wastes faster than shell plate. Tank steel is slower per tonne than shell steel: access is confined, ventilation and staging eat hours, and every renewed member needs surrounding coating reinstated — surface preparation in a closed tank is weather-independent but labour-hungry. If your gauging shows tank-frame wastage, budget tank days separately from shell days and insist the yard sequences tank crews independently, or the tanks will quietly become the critical path. Propeller and stern-gear work interacts with the same dock window — see our companion piece on propeller and shaft repair.
Facing a steel-heavy docking? Send your latest gauging report — the desk returns a realistic renewal timeline, yard options with real steel throughput, and a USD estimate. WhatsApp +62 811-3823-875 · sales@komodoluxury.com. National yard capacity is listed in the National Yard Register.
Reading the gauging report like a scheduler
The gauging report is usually read as a steel bill; read it instead as a schedule document and the docking plans itself. Three passes we run on every report. Pass one, geography: mark every renewal area on a profile drawing and count the distinct working zones — five tonnes spread across nine scattered locations takes longer than fifteen tonnes in two contiguous bands, because every zone pays its own staging, access and inspection overhead. Pass two, access: flag every renewal that sits behind an obstruction — tank internals, engine-room plating behind machinery, areas needing insulation strip-out — and price the access work into both budget and calendar before the yard discovers it mid-job. Pass three, sequence: identify which renewals gate other trades; shell plate in way of the coating schedule must finish early or the paint system waits on it, while internal frame renewals can run in parallel late into the stay. Owners who hand the yard a gauging report annotated this way get tenders with realistic timelines — and, more importantly, get to challenge unrealistic ones before contract instead of living with them in dock. Ten minutes with a highlighter on the gauging report is worth more schedule certainty than any clause you can write afterwards.
Frequently asked questions
How long does hull replating take at an Indonesian shipyard?
Roughly 1–3 tonnes per day per working front at a properly resourced yard: a 20-tonne renewal typically adds 10–18 working days, a 50-tonne special-survey renewal 3–5 weeks. Plate logistics and inspection rhythm move the number as much as welding speed.
What slows replating down the most?
Waiting: for plate stock, for gauging decisions, for fit-up inspections and for class witnessing. Pre-docking gauging, locked material lists and batched surveyor visits remove most of it.
Is ballast tank steel slower than shell plate?
Yes — confined access, staging, ventilation and coating reinstatement make tank steel materially slower per tonne. Budget tank days separately and have the yard run tank crews as an independent front.
How is replating quantity verified for invoicing?
By joint remeasurement against a plate map — each renewed plate’s dimensions and thickness recorded and signed as work completes. Without owner-side remeasurement, invoiced tonnage tends to grow.