While "small craft" is open to interpretation, when it comes to a weather warning for these boats, the National Oceanic and Atmospheric Administration (NOAA) is pretty clear. A Small Craft Advisory means there are either forecast or observed winds of 18 to 33 knots. In the case of a forecast, the warning can be issued upwards of 12 hours ahead of time. The same advisory can be issued for sea conditions or lower wind speeds that may make operating a small boat dangerous. Do yourself a favor and heed the warning.