Entry & progression
The part you did not carry is the part that stops the ship. Spares management is an engineering discipline, not a clerical one. It is also the second engineer's job, everywhere.
Criticality — the only sensible way to sort a store
| Class | What it means | Stocking rule |
|---|---|---|
| Critical | Failure stops the ship, or stops a safety system | Carry it. Carry the gasket and the fastener that go with it. |
| Essential | Failure degrades operation or redundancy | Carry it if lead time exceeds the tolerable downtime |
| Routine | Consumables, filters, seals, oils | Stock to consumption rate plus a season's margin |
| Non-critical | Comfort, convenience, cosmetic | Order as needed |
The classification is an engineering decision, and it is made by asking one question of every item: if this fails at sea, what stops? Not what is annoying. What stops. A steering ram seal is critical. A guest-cabin thermostat is not, however loudly the chief stew tells you otherwise.
Lead time is the whole problem
Criticality tells you what matters. Lead time tells you what to carry. An item you can have delivered anywhere in the world in 48 hours does not need to live on the boat. An item with a twelve-week manufacturing lead time does, even if it never fails — because when it does fail, the season is over.
- Manufacturing lead time — how long to make it. Nothing shortens this.
- Logistics lead time — how long to get it to you. Depends entirely on where you are.
- Customs and clearance — the invisible weeks. A part flown into a foreign port with the wrong paperwork is a part you do not have.
- Yard availability — a spare with no one competent to fit it is inventory, not a spare.
TIP — Your cruising ground changes the answer The same yacht, with the same machinery, needs a different spares inventory in the Mediterranean than it does crossing the Pacific. In Palma or Antibes the logistics lead time is a day and the store can be thin. Two weeks out of Fiji it is three weeks and a prayer. Re-run the inventory before every long passage. The itinerary is an engineering input.
Stock control that survives a crew change
A store that works
- Every part has a location, and the location is written in the system. A part you cannot find is a part you do not have.
- Every part has a part number — the manufacturer's, not yours. Descriptions lie; part numbers do not.
- Minimum stock levels are set per item, and the system flags the breach, not your memory.
- Draw-down is recorded when the part comes off the shelf, not when someone remembers at the end of the month.
- An annual physical count. The system is always wrong. The only question is by how much.
The budget
You will be given a number and asked to live inside it. The engineering answer is not to spend less; it is to spend earlier. Deferred maintenance is borrowed money at a punitive rate — the seal you did not replace for four hundred dollars becomes a bearing, then a shaft, then a yard period.
When the budget genuinely will not stretch, say so in writing, in engineering terms, to the chief: this job is deferred, this is what will fail, this is the likely cost when it does. That is not passing the buck. That is putting a decision in front of the person whose decision it is.