Field Notes · 4 February 2026
Safety stock that respects South Island lead times
Why textbook service levels fail when the next delivery is a ferry and a cartage day away.
Standard safety-stock formulas assume lead times that rarely match a supplier in Auckland serving a Timaru or Invercargill customer. Buffer stock has to reflect vessel and road reality, not a national average.
Measure the lead time you actually live with
Track order date to goods-available date for priority lines across a full season, including weather delays. Use the upper range for critical SKUs rather than the mean. Averages hide the storm week that empties the shelf.
Space is a constraint
Regional warehouses often lack the cubic capacity assumed in head-office models. Prefer higher buffers on a shortlist of revenue-critical lines, and accept stockouts on slow movers rather than filling aisles with low-turn inventory “just in case.”
Review rhythm
A monthly planning meeting that only reviews exceptions — lines that stocked out or aged — keeps the rules alive. If no one owns the reorder points after the consultant leaves, the buffers drift within a season.