A deck is a permanent covering over a compartment or a hull of a ship. On a boat or ship, the primary or upper deck is the structure that forms the roof of the hull, strengthening it. Decks for some purposes have specific names, the main purpose of the upper or primary deck is structural, and only secondarily to provide weather-tightness and support people and equipment. The deck serves as the lid to the box girder which is the hull. It resists tension, compression, and racking forces, the decks scantling is usually the same as the topsides, or might be heavier if the deck is expected to carry heavier loads. The deck will be reinforced around deck fittings such as the capstan, cleats, on ships with more than one level, deck refers to the level itself. The actual floor surface is called the sole, the term refers to a structural member tying the ships frames or ribs together over the keel. In modern ships, the decks are usually numbered from the primary deck. So the first deck below the deck will be #2. Some merchant ships may alternatively designate decks below the deck, usually machinery spaces, by numbers. Ships may also call decks by common names, or may invent fanciful and romantic names for a deck or area of that specific ship. Equipment mounted on deck, such as the wheel, binnacle, fife rails. Eastern designs developed earlier, with efficient middle decks and minimalist fore, in vessels having more than one deck there are various naming conventions, numerically, alphabetically, etc. However, there are various common historical names and types of decks,01 level is the term used in naval services to refer to the deck above the main deck. The next higher decks are referred to as the 02 level, the 03 level, afterdeck an open deck area toward the stern-aft. Berth deck, A deck next below the gun deck, where the hammocks of the crew are slung, Boat deck, Especially on ships with sponsons, the deck area where lifeboats or the ships gig are stored. Boiler deck, The passenger deck above the vessels boilers, may also refer to the deck of a bridge. Flight deck, A deck from which aircraft take off or land, flush deck, Any continuous unbroken deck from stem to stern
Image: Wrau olympic deck
The upper deck of the Falls of Clyde is iron; a centre strip is planked with wood as a sort of walkway. As is typical for a late-19th-century vessel, several deckhouses may be seen.