An operator running four boats on a route with no spare vessel. A part on the boat is money sitting still, and a part not on the island is a cancelled route.
The arrangement is simple and it is written down. We hold an agreed list of their fast wearing items in our own store, separated and labelled with their name. They pay for what they take, monthly, against the statement. They do not pay to have it sitting there.
It works because the list is short and it was chosen by their engineer rather than by us: filters, impellers, belts, sender units and the two hose sizes that always fail first.
In two years they have collected at short notice nine times. Three of those were at night, which is why the chief engineer has the shopkeeper's personal number and is one of about six people who do.