General Nautical Terminology | Nautical Topics | Depths & Clearance | Navigation | Safety | Sea State & Waves
Shoal
A shallow area or submerged elevation of the seabed that may pose a navigation hazard.
A shoal may consist of sand, gravel, mud, rock or coral and can lie near shore or offshore. Whether it is dangerous depends on charted and actual depth, tidal height, vessel draught, squat, waves and the required under-keel clearance.
Currents and waves can steepen or break over a shoal, while mobile sediment can shift its position and depth. Chart scale, survey quality, warnings and recent local information should be considered; ‘shoal’ can also be a verb meaning to become shallower.
