A guard ship is a warship stationed at some port or harbour to act as a stationary guard, as opposed to a coastal patrol boat which serves its protective role at sea.
In former times in the Royal Navy a guard ship usually was the flagship of the admiral commanding on the coast. In peacetime guard ships were usually larger ships of the line which were stationed in ports around the British coast. They were not laid up 'in ordinary' (with spars, masts, sails, rigging and guns removed and with the decks sheeted over the in canvas - the historic equivalent of a Reserve fleet) but were maintained by large (although not usual full) crews and had their spars and sails stored aboard. A port would be assigned a single guardship that would act as a naval headquarters for the area, while at larger ports and Royal Dockyards the guard ship would be the senior vessel present and used as a flagship. If war was declared or an enemy fleet was sighted the guard ships could be manned and ready for sea in a matter of hours or days, as opposed to the months it could take to recommission a ship 'in ordinary'. The use of guard ships in this way allowed the Royal Navy to maintain an effective defensive force (and a deterrent) without the expense and logistical problems of maintaining a complete sea-going fleet at all times.
A guard-boat is a boat which goes the round of a fleet at anchor to see that due watch is kept at night.
|This article about a type of ship or boat is a stub. You can help Wikipedia by expanding it.|