Demurrage

Per Lord Esher in Nielsen v Wait (1885) 16 QBD 67 at pp.70-71:

Other days are sometimes given also favour of the charterer, which are called "demurrage days." Those are days beyond the lay day but during which the amount that he has to pay for the use of the ship is a fixed sum, necessarily what it costs the owner to keep his ship, but a fixed sum, which is usually about what it is supposed it costs the owner to keep the ship. This stipulation also is in favour of the charterer, because instead of being involved in a dispute as to what he would have to pay for days during which the ship is kept idle, a sum is fixed, and he knows what he has to pay if he keeps the ship beyond the lay days

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