Modern marine turbochargers from ABB, MAN, Mitsubishi and Napier are designed to be serviced in two distinct ways: a cartridge exchange, where the rotating assembly comes out as a unit and a fresh one goes in, or a full overhaul where the existing cartridge is stripped, balanced, NDT-tested and rebuilt component by component. Both are legitimate. The decision usually comes down to time, location, and what is available.
When the cartridge swap wins
Cartridge exchange is the right answer when downtime is the dominant cost. A cartridge can typically be swapped in 8–12 working hours by a competent attending engineer, against 3–5 days for a full overhaul ashore. For a vessel on a tight schedule, on a charter where off-hire is on the operator, or in a port where the workshop fee structure makes the math obvious, the cartridge wins on every axis except the spare-parts invoice.
The catch is that cartridges have lead times. A new ABB A100 cartridge or a MAN TCA cartridge is rarely shelf stock outside of major hubs, and even when it is, the price moves with how urgent the order is. The cartridge-swap strategy works for fleets that plan it — ship managers running 20+ vessels often hold one cartridge per major engine type at a stocking location, and rotate it in and out of service.
When the full overhaul wins
Full overhaul is the right answer when time is not the binding constraint and the cartridge has another generation of life in it. The economics are simple: an overhaul kit (bearings, seals, nozzle ring, sometimes a rotor) is a fraction of a new cartridge, and a properly overhauled unit returns to service essentially as good as new for that running-hours window.
The two situations where full overhaul makes sense:
- The vessel is in a yard for an unrelated reason — drydock, major engine work, or a survey — and the turbocharger work fits inside the existing window at no marginal time cost.
- The fleet has a long-standing relationship with a turbocharger workshop and the per-unit overhaul cost is well below what new-cartridge pricing implies.
The hybrid approach
The pattern we see most often from large managers is a hybrid: a cartridge stays in service through one overhaul cycle, then gets replaced with a new or refurbished cartridge at the second cycle. That model balances the cartridge inventory cost against the per-overhaul cost, and it gives the engineering team flexibility about which approach to apply at each PMS interval.
Whichever route you go, the parts decision wants to be made well ahead of the work. A nozzle ring on a 2–3 week air-freight is not where you want to be at the start of a layby.
