In naval architecture

Naval architecture

Naval architecture is an engineering discipline dealing with the design, construction, maintenance and operation of marine vessels and structures. Naval architecture involves basic and applied research, design, development, design evaluation and calculations during all stages of the life of a...

, a Mack is a structure which combines the radar MAsts and the exhaust stACK of a surface ship, thereby saving the upper deck space used for separate funnels and the increasingly large lattice masts used to carry heavy radar

Radar

Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 aerials. The word itself is a composite of "mast" and "stack". It is a common design feature on postwar warship

Warship

A warship is a ship that is built and primarily intended for combat. Warships are usually built in a completely different way from merchant ships. As well as being armed, warships are designed to withstand damage and are usually faster and more maneuvrable than merchant ships...

s, (e.g. the rebuilt Baltimore class cruiser

Baltimore class cruiser

The Baltimore class cruiser was a type of heavy cruiser in the United States Navy from the last years of the Second World War. Fast and heavily armed, ships like the Baltimore cruisers were mainly used by the Navy in World War II to protect the fast aircraft carriers in carrier battle groups...

s), and on some Cruise ships.

The Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 used this design feature on the 1944 Weapon class destroyer

Weapon class destroyer

The Weapon class was a class of destroyers built for the British Royal Navy towards the end of World War II. They were the smaller counterpart to the Battle class and were the first new destroyer designs for the Royal Navy since the Second World War Emergency Programme...

s, and the subsequent Darings

Daring class destroyer (1949)

The Daring class was a class of eleven destroyers built for the Royal Navy and Royal Australian Navy . Constructed after World War II, and entering service during the 1950s, eight ships were constructed for the RN, and three ships for the RAN. Two of the RN destroyers were subsequently sold to and...

, as well as the diesel-engined Type 41 "Cat" class

Leopard class frigate

The Type 41 or Leopard class were a class of anti-aircraft defence frigates built for the Royal Navy and Indian Navy in the 1950s. These ships were designed to provide anti-aircraft escorts to convoys, as a result they were not built for fleet speeds and made only...

 and Type 61 "Cathedral" class

Salisbury class frigate

The Type 61 Salisbury class were a class of British aircraft direction frigates built for the Royal Navy. They were related to the Type 41 Leopard class frigates, but with reduced armament to make way for more aircraft direction equipment.-Construction Programme:Three further ships of the class...

frigates of the 1950s. It provided unbalanced and unattractive designs, which led to a reversion to separate masts and funnels in subsequent RN vessels.