Miles Per Hour

Miles per hour (mph) is a speed unit based on statute miles travelled in one hour. In boating it may appear on some instruments, local notices, or weather settings, but it is not the standard offshore navigation unit; at sea, speeds are normally expressed in knots. One mph equals about 0.87 knots.

For boaters, mph matters mainly when converting between systems for estimated arrival times, fuel range, speed restrictions, and interpreting wind or vessel-speed data. Confusing mph with Knots can distort passage plans because Nautical Miles are longer than statute miles. It is also important when comparing forecast Wind Speed values across different unit settings.

PredictWind lets users choose preferred units in the Forecast App and web forecasts, so mph can be displayed where familiar. For offshore routing, routing calculations and chart work are usually best kept consistent with nautical units, especially when reviewing GRIB data, GPS tracks, and Weather Routing results.