Conversions & Retrofits
Conversion Engineering
Navtech specialises in ship conversion engineering — changing what a vessel can carry, how it operates or which regulations it meets. Oil-to-bitumen conversions, BWTS and scrubber retrofits, barge modifications and deck strengthening, delivered as one coordinated, class-approved package.
Oil-to-bitumen tanker conversion
Bitumen conversions are our most repeated scope, and we work from a process refined across more than fifteen projects. The engineering problem is that everything interacts: thermal oil heating changes the structure through expansion, the insulation changes the weight, the boilers change the power balance, and all of it changes the stability booklet. Treating those as one package rather than four separate submissions is what keeps approvals clean.
- Thermal oil boiler sizing, system design and heating coil layout
- Heat-loss calculations and cargo tank insulation specification
- Structural reinforcement for thermal expansion and new foundations
- Cargo pump, piping and valve modification for heated cargo
- Electrical load reassessment and generator adequacy checks
- Updated stability booklet, damage cases and loadicator data
BWTS, scrubber and compliance retrofits
Regulatory retrofits are dominated by two constraints: the equipment has to fit a space that was never designed for it, and the dry-dock window is fixed. We survey and 3D scan the machinery space first, then design into the real geometry, which is what prevents the fit-up problems that consume dock days.
- Ballast water treatment system (BWTS) integration and tie-in design
- Exhaust gas cleaning system (scrubber) installation and routing
- EEXI compliance, engine power limitation (EPL) and CII improvement
- Equipment foundation and structural interface design
- Commissioning support and as-built documentation
Barge modification and deck strengthening
Working craft are regularly repurposed — a cargo barge becomes a crane platform, a deck is strengthened for heavier equipment, a helideck is added. Each of these changes the global strength and stability picture, and each needs to be demonstrated rather than assumed.
- Barge conversion for crane and heavy-lift operations
- Deck strengthening for new equipment and concentrated loads
- Helideck design and installation to CAP 437 and class rules
- Spud, winch and mooring system additions
- Canopy, accommodation and outfitting modifications
How we run a conversion project
Conversions carry more risk than newbuilds because the starting condition is uncertain. Our sequence is designed to remove that uncertainty early, while changes are still cheap.
- Survey and 3D laser scan to establish the vessel’s actual as-is condition
- Feasibility study covering capability, class implications, cost and schedule
- Basic design across all affected disciplines, developed together
- Class submission and management of the comment cycle to approval
- Production drawings and yard support through installation and commissioning
Frequently asked questions
How many bitumen tanker conversions have you completed?
More than fifteen. That repetition matters — we know which details class societies question, how the thermal system interacts with the structure, and where the schedule risk sits. It is the difference between designing a bitumen conversion and having a process for one.
Can conversion engineering be completed within a dry-dock window?
Yes, provided the design work starts well before the vessel arrives. The survey, 3D scan, design and class approval should all be complete before dock entry so that the yard period is installation only. Conversions that begin engineering after dock entry are the ones that overrun.
What happens if the vessel’s original drawings are missing or wrong?
This is normal on older tonnage and we plan for it. We 3D laser scan the affected spaces and rebuild an accurate as-built model, then design against that. It also gives you a reliable drawing set for future projects, which many owners find is worth as much as the conversion itself.
Do you handle the class approval or do we?
We handle it. Documentation is prepared to the reviewing society’s templates, submitted, and carried through the comment cycle to stamped approval. We work regularly with BV, DNV, RINA, ABS, IRS and Tasneef.
Can you assess whether a conversion is worth doing before we commit?
Yes, and we recommend starting there. A feasibility study covering structural capacity, stability margins, class implications, budget cost and schedule tells you whether the conversion is viable before significant money is committed. Occasionally the honest answer is that a different donor vessel is a better buy.
Related engineering services
Have a vessel and a scope in mind?
Share your drawings, class society and target dates — we respond within 24–48 hours.