A long sea implies an uniform and steady motion of long and extensive waves; on the contrary, a short sea is when they run irregularly, broken, and interrupted; so as frequently to burst over a vessel's side or quarter.

Hence a ship is said to be tight, when her planks are so compact and solid as to prevent the entrance of the water in which she is immersed: and a cask is called tight, when the staves are so close that none of the liquid contained therein can issue through or between them.

Hence a ship is said to head the sea, when her course is opposed to the setting or direction of the surges.

William Falconer Quotes