Draft (nautical)

:''For use in sailing, see draft (sailing)

In nautical parlance, draft or draught is the clearance required to safely pass.

A quay's draft is the available depth of water at low tide.

Vessels also have a draft, which is the depth below water's surface of the lowest part when fully-laden. It determines the minimum depth of water that the vessel may pass through. Riverboats are often purposely designed with a shallow draft to avoid sandbars and other obstacles. As such, a vessel's draft must be lower than the draft of any quay it wishes to berth at.

Related to the normal draft, is air draft which is the clearance required for a vessel above the water -- this is typically quoted for bridges over waterways as well as any other restricitons such as power lines or tunnels.