The toolbox: what each calculator result means for a contract

The toolbox collects sixty calculators: anchor chain, range on the rule of thirds, Beaufort and wave height, antifouling quantity, battery capacity, service intervals, safe depth, survival time in cold water and more. All of them use the standard formulas of seamanship. No sign-up, no email address, nothing stored.

What matters more is the second half of each page. It explains what the result means when a contract is read later. Take the service planner: a documented oil change moves the discussion after an engine failure away from the question of wear and towards the question of what actually happened, and that is a different conversation with a surveyor.

Several of them are built for the situations a visiting crew runs into rather than a local one. The lock time calculator matters on inland waterways where a day stage is set by the number of chambers, not by distance. The safe depth calculator matters where the chart datum and the actual water level diverge, which in the western Baltic happens with a strong easterly.

For the common types there are preset versions: range for a jet ski assumes 70 litres and 35 litres per hour, for a motor yacht 900 and 90. Those presets are averages and no substitute for your own fuel log, which is why each page says so.