Editing Three-decker (section)

{{about|the type of warship|the residential building type|Three-decker (house)|the book format|Three-volume novel|other uses|Three-decker (disambiguation)}}
{{Refimprove|date=October 2012}}
[[Image:HMS Britannia Chambers mg 0529.jpg|thumb|Three-decker [[HMS Britannia (1820)|''Britannia'']] in Portsmouth Harbour, 1835]]
[[Image:MuseeMarine-Ocean-p1000422.jpg|thumb|Batteries of the 118-gun ''[[French ship Océan (1790)|Océan]]'']]

A '''three-decker''' was a sailing warship which carried her principal carriage-mounted guns on three fully armed [[Deck (ship)|decks]]. Usually additional (smaller) guns were carried on the upper works (forecastle and quarterdeck), but this was not a continuous battery and so did not count as a "fourth deck". Three-deckers were usually "[[Ship of the line|ships of the line]]", i.e. of sufficient strength to participate in the line of battle, and in the [[rating system of the Royal Navy]] were generally classed as [[first rate|first]] or [[second rate|second]] rates, although from the mid-1690s until the 1750s the larger of the [[third rate]]s were also three-deckers.

Three-deckers also served in the naval forces of other European states, notably those of France, Russia and Spain. The French definition of a three-decker differed from that of the English Navy until 1690, as some ships that were officially termed "three-deckers" prior to this date had only a partially-armed third tier of guns, with a significant gap between the guns in the forward portion of that deck and the guns in the aft portion of that deck. In some of these nominal three-deckers this division constituted a structural gap separating the forward and aft sections of this deck, so that these vessels would have been described as "two-deckers" in equivalent English warships.<ref>Winfield, Rif & Stephen S Roberts, ''French Warships in the Age of Sail 1626-1786: Design, Construction, Careers and Fates'' (2017, Seaforth Publishing) {{ISBN|978-1-4738-9351-1}}.</ref><ref>Lemineur, Jean-Claude. ''The Sun King's Vessels'' (1996, A.N.C.R.E.) {{ISBN|978-2-903179-88-5}}.</ref>