An overview for fleet managers, technical inspectors and shipyard superintendents: which machining capabilities are possible directly on board or in the dock, how are the strict requirements of the classification societies met, and how can berthing and docking time be reduced to a minimum through mobile machining?
Everything from a single source at HSOS. We carry out demanding mechanical machining directly on the ship or in the shipyard – from face milling of large foundations to the boring of shaft lines, without having to dismantle huge components ashore. We coordinate the procedure and the required tolerances precisely with your shipyard specifications and the inspectors.
1 · Scope of maritime machining and capabilities
We flexibly adapt our mobile machine technology to the massive and often inaccessible components found in the shipping industry. Our range of services includes:
- ▸Foundations and frames (face milling): High-precision face milling of engine foundations, crane foundations, winch seats and gearbox seats to ensure a perfectly flat bearing surface for resin (casting compound) or steel fitting pieces (chocks).
- ▸Shaft lines and rudders (mobile boring): Boring of stern tubes, rudder trunks and bow/side thruster housings to precise dimensions, even in cases of asymmetric wear.
- ▸Engine blocks (line boring): Re-machining and in-line boring of crankshaft bearing bores directly within the ship’s engine.
- ▸Pipework and special flanges (flange machining): On-site machining of damaged sealing faces on cargo lines (tankers), sea cooling-water valves and hatch covers directly in place.
2 · Certified quality to maritime standards
At sea there are no compromises on reliability. We machine precisely to the tolerance and surface specifications of the maritime industry and prepare the components for acceptance by the leading classification societies:
- ▸DNV, Lloyd’s Register (LR), Bureau Veritas (BV), ABS: Compliance with the required dimensional tolerances and surface finishes (Ra/Rz) for safety-critical ship components.
- ▸Alignment and flatness: Production of high-precision angles and geometric alignments that are essential for the vibration-free running of heavy marine diesel engines and shaft lines.
3 · Machining under real-world conditions in shipbuilding
Mobile machining on ships rarely takes place under laboratory conditions. Whether on a vibrating hull afloat, in the cramped, hot engine room, below deck in constrained and overhead positions, or outside in the dry dock in harsh weather – our machine systems and cutting tools are specially matched to the tough conditions of maritime practice.
4 · Quality and safety: laser measurement and measurement reports
Critical factor: alignment and fit dimensions. With rotating equipment such as propeller shafts or large marine diesel engines, hundredths of a millimetre often determine vibration, bearing wear and service life. Mobile machining therefore requires not only powerful machines but also highly precise alignment. Before machining begins – for example when boring a stern tube or milling a gearbox foundation – we determine the actual condition.
Seamless quality assurance for inspectors: for fleet managers and shipyard superintendents, complete documentation for the classification society (Class) is decisive. Every machining step is accompanied by our metrology, often supported by state-of-the-art laser measurement technology. The final measurement report transparently documents compliance with the required roughness depths, flatness values and bearing tolerances. This solid data basis ensures a smooth process during Class acceptance and recommissioning.
5 · Optimal preparation: what you can do for a smooth process
Berthing and docking time in shipyards is tightly calculated. For maximum efficiency, you as the client can prepare the work areas on board. As a general rule: everything is feasible, and we agree on the exact procedure together before docking or the shipyard stay.
- Dismantling: Obstructing edges such as adjacent pipework, covers or old chocks should be removed in advance to create space for mounting our mobile milling or boring machines.
- Cleaning: A rough cleaning of the components to remove oil, grease, rust and barnacles greatly speeds up measuring and alignment.
- Accessibility & logistics: Moving the machines into the engine room often requires the use of chain hoists or shipyard cranes. Clear transport routes and defined lifting points on the component (or above it) are ideal.
- Scaffolding: For work on the outside of the hull (e.g. thruster or rudder) or high up on deck cranes, a stable working scaffold approved for the machine load is required.
- Power supply: Providing energy in the immediate vicinity of the component speeds up the start of work. Pneumatic drives require compressed air (usually 8 Bar and approx. 2,000 to 3,000 litres, depending on the machine used).
- Lighting & ventilation: Especially in enclosed tanks or deep in the engine room, adequate lighting and ventilation (observing explosion protection) ensure a safe and rapid workflow. If required, HSOS brings self-sufficient equipment.
- Permits: Strict safety requirements apply in shipyards and on ships. The timely issuing of work permits (Hot Work Permit, Confined Space Entry, LOTO) enables a direct start.
FAQ
Does the ship absolutely have to go into the dry dock for machining?
Not always. Many jobs (e.g. face milling of winch foundations on deck or work in the engine room) can be carried out afloat (while floating in the water) or during port stays for loading/discharging. Work below the waterline, such as on stern tubes or rudder trunks, generally requires a dry dock.
Can large engine foundations be milled directly in the engine room?
Yes. This is one of our specialities. Instead of cutting the engine block or entire frame structures out of the ship, we bring modular, mobile linear milling machines directly into the engine room. In this way we produce the required flatness for the subsequent chocking directly on site.
What happens if there is no adequate power supply available on board?
This is not uncommon in the case of casualties or ships in cold lay-up. Depending on the design, our machines can be driven electrically, hydraulically or pneumatically. The rule here is: we always bring our own hydraulic power units. The required compressed air (compressor) can either be provided by you or, by arrangement, brought along by us. Electrical power must as a rule be provided by the shipyard or the ship – but should this not be possible, we are of course also happy to help here with a mobile generator set by prior arrangement.
Are the works recognised by the classification societies (DNV, LR, etc.)?
Yes. We machine precisely to the drawing tolerances specified by the shipyard or the owner. Through our precise measurement reports (often supported by laser trackers) we provide the classification society inspectors with exactly the reliable data that is essential for certification and release of the component.
How much time does the machining take during a docking period?
The machining time depends on the component size and the required material removal. However, since the considerable time needed for removal, transport ashore and reinstallation is eliminated entirely, mobile on-site machining drastically reduces berthing and docking time (and thus dock costs). We often work in multi-shift operation to fit optimally into the shipyard’s schedule.
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