Architectural-constructive types of ships

Forms of the main hull of ships

The geometry of the main hull is defined by the shape of the stems, the camber line and keel line, as well as the stern contours, which are influenced, among other factors, by the number of propellers. The diagram below illustrates the most common bow configurations used in seagoing vessels.

Conventional ocean-going cargo ships typically feature a straight stem inclined forward. This gives the hull a more streamlined appearance, improves seakeeping performance, and reduces deck wetness. Ice-class transport vessels, as well as certain tugboats, are equipped with a so-called semi-icebreaking bow form—characterized by an underwater stem inclination of about 40–50° and an almost vertical above-water section. The inclined underwater portion enhances navigation in broken ice, while the nearly vertical upper stem allows the vessel to follow an icebreaker by pressing its bow into a specially designed notch at the stern of the leading ship. For dedicated icebreakers, the underwater stem is designed with a smaller inclination, typically around 25–30°, to further improve ice performance.

High-speed passenger liners and fast vessels often feature a bulbous bow below the waterline combined with clipper-style shaping above it. The bulb reduces wave formation and hydrodynamic resistance, while the clipper bow contributes to a sleeker profile and minimizes deck wetness. The term “clipper bow” originates from the clipper ships, which had a similar stem design.

In recent decades, the bulbous bow has been widely adopted on tankers and bulk carriers operating at moderate speeds. For these full-form hulls, the bulb helps refine the forward waterlines near the keel region, thereby reducing form resistance.

Smaller fishing vessels, such as trawlers and seiners, usually have a rounded, spoon-shaped stem.

More recently, a new hull concept known as the X-bow has emerged in shipbuilding. It is widely used in offshore vessels and was notably first applied in the design of the Zumwalt-class destroyer.

Shapes of the bow of sea vessels

1 — the bow of a transport vessel with a straight, sloping stem; 2 — the bow of an ice-going vessel; 3 — the bow of an icebreaker; 4 — the spoon-shaped bow of a fishing vessel; 5 — the bow of a clipper with a bulb; 6 — the bulb-shaped bow of an oil tanker; 7 — the bow of an X-bow type

Stern end shapes of ships

The shape of a ship’s stern can vary widely; however, the most common types are the cruiser stern, the conventional stern, and the transom stern.

For high-speed seagoing transport vessels—whether cargo ships, passenger liners, or similar types—the cruiser stern is the most typical configuration. The conventional stern with an overhang is more characteristic of slow-moving and inland waterway vessels, while the transom stern is commonly found on specialized ships, high-speed boats, and similar craft.

The stern design largely depends on the number of propellers. In single-screw vessels, a relatively large recess or “aperture” is formed in the centerline plane at the stern in way of the propeller. In twin-screw ships, the stern lines must also accommodate the proper placement of the propellers. For this reason, when referring to the architectural type of a vessel, the number of propellers is always specified.

The geometry of the underwater stern is further defined by the shape and length of the deadwood—the narrow aft extension of the hull into which the keel structure continues.

Shapes of the stern end of sea vessels

1 — elliptical stern;2 — cruiser stern;3 — transom stern

Number and location of superstructures

Based on the number and arrangement of superstructures, ships are classified into the following architectural types:

• Three-island vessels, which feature three superstructures: a forecastle, a midship superstructure, and a poop deck.
• Two-island vessels, which have two superstructures, most commonly a forecastle and a poop.
• Quarterdeck vessels, ships equipped with a quarterdeck— a localized elevation of the upper deck by approximately 0.8–1.2 meters in the aft section.

Architectural and structural types of ships, distinguished by the number and location of superstructures

1 — three-island vessel; 2 — two-island vessel; 3 — two-island vessel with extended forecastle; 4 — two-island vessel with extended poop; 5 — single-island vessel with forecastle; 6 — single-island vessel with poop; 7 — vessel with continuous superstructure (shelterdeck vessel); 8 — flush-deck vessel without superstructures; 9 — quarterdeck vessel

Architecture of the ship's exterior

Options for the location of the main superstructure on container ships

The overall architectural appearance of a vessel is shaped not only by the form of the main hull—primarily selected based on operational and technical requirements—but also by the design of the superstructures, the number of deck levels, the configuration of bulwark openings, the shape and number of funnels, as well as the color scheme of the hull and superstructures. Continuous refinement of external ship forms, driven by the creative contribution of naval architects, has resulted in modern vessels exhibiting dynamic, streamlined silhouettes consistent with contemporary design principles.

Superstructures and deckhouses on modern ships are typically streamlined; bulwark openings are inclined forward, and the length of deckhouses—depending on the number of tiers—is optimized to achieve a balanced and dynamic profile. Transitional brackets between the forecastle and the bulwark, as well as the bow visor, are often elongated in shape. Funnels are commonly designed with a conical form, featuring an inclined upper section and a rounded top edge. On many diesel-powered vessels, the funnel is integrated with the signal mast. In some cases, twin funnels are arranged side by side, allowing for more efficient routing of exhaust ducts and offering advantages—particularly for wide-beam ocean-going ships, such as supertankers, bulk carriers, and passenger liners.

The vessel’s architectural layout is also influenced by the longitudinal position of the engine room, as this determines the placement of the main accommodation block and the funnel. While ships built before the early 1950s typically featured a midship engine room arrangement, modern seagoing transport vessels more commonly employ either an aft-shifted (“intermediate”) position or a fully aft configuration.

Today, nearly all tankers and bulk carriers have the engine room and accommodation located aft. This arrangement offers several significant advantages:

• it frees up valuable cargo space in the midship section;
• reduces the internal volume occupied by machinery spaces;
• shortens the shaft line, thereby decreasing its weight and increasing the vessel’s payload capacity;
• eliminates the need for a propeller shaft tunnel running from the engine room to the stern.

Such a tunnel, when passing through cargo holds on vessels with a midship engine room, reduces usable cargo volume and complicates cargo handling operations.

However, a fully aft arrangement of the engine room and accommodation also introduces certain drawbacks: it complicates trim control, may reduce onboard living comfort, increases the forward blind zone, and often requires a longer engine room. Therefore, the choice of a particular architectural configuration is determined on a case-by-case basis, taking into account the vessel’s purpose and operational profile. As a result, even among modern ships, one can find vessels with aft, intermediate, and midship engine room arrangements.

Classification of ship spaces

The ship's premises are located in the main hull and superstructures.

Main hull

The main hull includes all spaces formed by the outer hull plating, the continuous upper deck, as well as the decks, platforms, main transverse and longitudinal bulkheads, and enclosures located internally. Spaces formed by the main hull structures are further subdivided into compartments and other ship spaces formed by enclosures and decks in the superstructures, deckhouses, and the main hull. The most important compartments of the hull include:

• forepeak — the outermost forward compartment
• afterpeak — the outermost aft compartment
• between bottoms — the space between the outer hull plating and the double bottom
• hold — the space between the double bottom and the nearest deck
• tweendecks — the spaces between adjacent decks of the main hull
• deep tanks — deep tanks located above the double bottom
• cofferdams — narrow, oil- and gas-tight dry compartments located between compartments or tanks for petroleum products and adjacent spaces
• main and auxiliary machinery compartments
• propeller shaft tunnel — on ships with an engine room amidships

The presence of the above compartments on specific ships is determined by the purpose and design of the vessel.

Layout of ship spaces on a car-passenger ferry: spaces for cars - white; spaces for passengers - blue; crew service spaces - gray; deck numbers - yellow

Superstructures

Superstructures are located on the upper continuous deck of the main hull. They extend across the width of the vessel: either from side to side, or so that their sides are no more than 0.04 times the width of the vessel. Superstructures serve not only to accommodate ship's accommodations but also to improve the seaworthiness of the vessel.

• Forward superstructure—the forecastle—reduces deck flooding.
• Aft superstructure—the poop, by increasing the freeboard at the stern, increases the vessel's buoyancy and unsinkability in the event of damage to the stern or a trim by the stern.
• Midship superstructure—the poop—increases buoyancy.
• Conning towers differ from superstructures in their narrower width. They are installed on the upper deck of the main hull or on superstructures (on warships, conning towers located on the upper deck are called superstructures).

Layout of the public areas and staterooms on the Brilliance of the Seas cruise ship

Ship Spaces

Depending on their purpose, all ship spaces are subdivided into special, utility, residential, public, domestic, catering, sanitary and hygienic, medical, workshop, ship's store and supply compartments, and compartments for fuel, water, oil, and ballast water.

Special Spaces

Depending on the vessel's purpose, special spaces are used:

• for cargo storage (cargo holds) on cargo and cargo-passenger vessels
• for specialized technological equipment during fish processing on fishing vessels
• for laboratories on research vessels. Special spaces also include hangars for helicopters and helicopter servicing spaces.

Service Spaces

Service spaces are designed to ensure the normal operation of the vessel as a floating structure. These include:

• main and auxiliary machinery rooms
• rooms for deck machinery and ship systems machinery — steering gear compartment, carbon dioxide fire extinguishing stations, remote cargo level measurement station, fuel receiving and dispensing stations, ventilation rooms, air conditioning rooms
• wheelhouses, navigation rooms and stations — helmsman's room, chart room, radio room, log and echo sounder room, gyrocompass room, fire stations, emergency stations, broadcasting room, battery rooms, unit rooms
• workshops — mechanical, metalworking, electrical, welding station, watercraft repair shop, instrumentation workshop
• administrative spaces — ship's office, engine room, cargo office, administrator's office, ship's archive, control room

Living Spaces

Living quarters (cabins) are intended for the permanent residence of the ship's crew and for accommodating passengers. Crew cabins are divided into officers' cabins and crew cabins, which differ in location, area, and equipment. Crew cabins designed to accommodate more than four people are usually called a forecastle.

Passenger cabins, depending on their location, area, number of berths, and equipment, are divided into suites, first-, second-, and third-class cabins. On most modern liners, second- and third-class cabins are typically replaced by a single, so-called tourist class. On local passenger ships, seating areas are provided.

Public Spaces

Public spaces are used to organize and host various cultural events and cater for crew and passengers. This category includes public spaces for the ship's crew and separate public spaces for passengers, as well as areas on open decks and walk-through spaces. Crew public spaces include the wardroom, officers' and crew lounges, dining rooms, gymnasium, and swimming pool. Passenger public spaces include restaurants, bars, cafes, salons (massage, music, smoking, games, and relaxation), a concert hall, gymnasium, swimming pools, a library with a reading room, and children's rooms. Open deck areas include verandas, promenade decks, solariums, outdoor swimming pools, and sports grounds. Walk-through spaces include corridors, vestibules, lobbies, foyers, and enclosed promenade decks.

Service Facilities

Service facilities are equipped on passenger ships, expedition vessels, and large fishing vessels. These include tailor shops, hairdressers, beauty salons, photo studios, shops, and storage lockers.

Kitchen Facilities

Kitchen facilities are used to prepare and serve food to the crew and passengers, as well as to wash and store tableware. A distinction is made between galley facilities (passenger galley, crew galley, bakery, and supply rooms for the galley and bakery) and preparatory facilities (meat, fish, and vegetable cutting rooms, bread cutting, pantry, dishwashing rooms, and storage rooms for tableware and table linen). H4 Sanitary and Hygienic Premises

Sanitary and hygienic spaces are subdivided into sanitary and domestic (laundry, drying, ironing, clean and dirty linen storage, disinfection chamber, work clothes rooms) and sanitary and hygienic (men's and women's washrooms, showers, bathtubs, baths, and toilets).

Medical Premises

Medical spaces include an outpatient clinic, doctor's office, operating room, X-ray room, dental room, isolation room, pharmacy, and sanitary pantry. A complex of medical care spaces on ships is usually called a medical unit.

Ship's Stores and Supply Rooms

Ship's storerooms and supply rooms are used to store provisions, skipper's supplies, navigational equipment, and other ship's equipment. These include:

• provision storerooms, both unrefrigerated (for dry provisions, bread, and flour) and refrigerated (for wet provisions, meat, fish, vegetables, dairy products, fats, and canned goods), as well as refrigeration chambers
• utility storerooms – for storing carpets, covers, sports equipment, and cleaning equipment
• skipper's storerooms – skipper's, painter's, lantern, carpenter's, rigging, awnings and tarpaulins, and sails
• navigation and navigation storerooms – for navigational equipment, charts, and other items
• linen and storage rooms

Compartments and Tanks

Compartments and tanks are used to store liquid cargo – oil, water, grease, and ballast water. In addition to the compartments formed by the main hull structures and intended for the placement of the main quantity of liquid cargo, ships also have tanks in which large, expendable reserves of fuel, water and oil are placed (the so-called insert tanks).

General Arrangement of a Ship

The general arrangement of a ship refers to the general layout of all spaces within the hull, superstructure, and deckhouse intended to accommodate the vessel's main and auxiliary machinery, ship equipment, ship's stores, cargo, crew, and passengers, as well as all service stations, domestic, utility, and sanitary spaces.

On ships of the same type and similar sizes, their general arrangement may vary, depending on customer requirements. However, recently, the global shipbuilding industry has been standardizing ship spaces, primarily residential and service spaces.

Location of Ship's Spaces

To help identify the location of various spaces on a ship, the following deck and interdeck names are used:

in the hull (from top to bottom):

• upper deck
• second deck
• third deck (on multi-deck vessels, the last deck is called the lower deck)
• double bottom

in superstructures and wheelhouses (from bottom to top):

• deck of the first tier of the superstructure (forecastle, poop deck, middle superstructure)
• deck of the second tier of the wheelhouse
• decks of the third tier of the wheelhouse, etc.

Sometimes these terms are supplemented by names that characterize the purpose of the decks: promenade deck, saloon deck, boat deck, sports deck, lower (navigation) bridge, upper (navigation) bridge.

The space between the outer hull plating and the double bottom is called the double bottom. The space between the double bottom and the nearest deck is called the hold, while the remaining spaces between decks are called tweendecks.

The position of the space along the length and width of the vessel is designated by the numbers of the frames that define the space along its length and the name of the side of the ship on which it is located.

Special Spaces

Special spaces—cargo holds, catch processing and storage spaces—occupy the majority of the hull space on cargo, cargo-passenger, and fishing vessels. The layout of these spaces is determined by the requirements for cargo handling operations, cargo storage and stowage, catch receipt, processing, and storage, and so on. The location of these special spaces, which determine the vessel's operational and economic performance, governs the layout of all other ship spaces.

Service Spaces

Service spaces are located throughout the vessel, primarily in the hold, at the ends of the vessel, in deckhouses on the upper deck, in forecastle and poop spaces, and sometimes in areas where living quarters are prohibited, such as above the forepeak and afterpeak and below the waterline. Some navigation spaces—the wheelhouse, chartroom, and radio room—are located on the bridge; the log and echosounder rooms are on the second deck. Workshops are typically located near the engine and boiler rooms.

Living Spaces

Crew quarters on cargo ships are typically located in the superstructure or below the upper deck of the main hull, but not below the waterline, preferably closer to the middle of the ship, where the motion and vibration from the propellers are least noticeable. An exception are cargo ships with a purely aft engine room: here, all crew quarters are located in the aft superstructure. On passenger ships, crew cabins are located forward, aft, and below the passenger cabins, while the officers' cabins are on one of the upper tiers of the superstructure, usually near the wheelhouse (one tier below). The captain's cabin is usually located on the starboard side, one tier below the wheelhouse. All navigator cabins are located here or one tier below; the cabins of the chief engineer, engineers, and engine crew are located as close to the engine room as possible. Deck crew cabins are located on the starboard side, and engine room cabins are located on the port side.

Passenger accommodations on passenger ships are located amidships whenever possible, preferably in the superstructures and upper 'tweendecks of the main hull. Placing passenger cabins below the bulkhead deck is not recommended, and below the waterline is prohibited. Passenger cabins typically have natural light, but on larger ships carrying large numbers of passengers, some cabins lack natural light.

Public Spaces

Prime areas of the superstructure and decks with good visibility are allocated for public spaces. Some public spaces—restaurants, theaters, indoor swimming pools, gymnasiums, and the like—are located in spaces without natural light.

Service Spaces

Service spaces are located near public spaces, but they generally lack natural light. Mess rooms should be located close to the facilities they serve. For example, the galley or bakery is located near the crew mess hall, wardroom, or restaurant, usually on the same deck or below them, with a special elevator for transporting food from the galley to the pantries. Provision stores are located adjacent to or one or two tiers below the galley. When locating provision stores, the ease of loading provisions onto the ship using the ship's own means is essential. H4 Sanitary and Hygienic Facilities

Sanitary and hygiene facilities are located in close proximity to the living quarters or in the same block. The bath and laundry block is located in the aft section of the hull below the upper deck, in an area not used for permanent occupancy.

Medical Block

The medical block is located in the superstructure, usually amidships, away from the main corridors and areas where crew and passengers congregate.

Ship's Stores and Supply Rooms

Ship's storerooms and supply rooms are located near the living and public spaces (storage rooms for cleaning equipment, carpets, rugs, covers, and sports equipment), as well as on the open decks (storage rooms for emergency and rescue equipment and diving equipment). Fuel, boiler feedwater, oil, and ballast water are stored in double-bottom compartments and deep tanks, which are located near the engine room and forepeak. The forepeak and afterpeak are typically used as ballast tanks. Fuel tanks are located near the engine room. Fresh drinking water is stored in separate tanks.