A lattice mast is a type of mast that is comprised of an open weave of steel strips, much like that of a lattice fence. Used on battleships built at the end of World War I for observation towers, the open design of the lattice mast allows an enemy shell to pass through without sustaining the same amount of damage as a solid steel tower would experience from a direct hit. Another feature of the lattice mast is that it absorbs much of the recoil of the large deck guns when they are fired. The observation crew was subject to far less shock and recoil when directing fire towards distant targets, making for more accurate targeting and subsequent firing of the gun crews.
Prior to the inception and perfection of radar, the gun crews of war ships relied on observers perched high above the ship in observation or lookout towers. The towers were first built on solidly enclosed structures that were very vulnerable to enemy fire. A glancing hit on the enclosed tower would often result in the total demise of the tower. This would often force the withdrawal of the vessel due to the inability to direct fire properly. This was eliminated by the use of the lattice mast.
By assembling a tower much like the Eiffel tower on a ship's superstructure, the enemy shells could potentially go through without hitting any solid structure. Even when hit solidly in one section of the lattice mast, the result was typically the loss of the single strip of steel that was hit by the shell. The observation crew was also cushioned by the lattice construction that would absorb much of the large guns' recoil. This resulted in much more accurate targeting of the guns during extended gun fights between ships. The lightweight lattice mast construction, as compared to conventional enclosed towers, also eliminated much of the topside weight in rough seas.
Once used on nearly all the battleships and gunships of the world's navies, the lattice mast was virtually made obsolete by the implementation of radar and the computer-aided targeting systems used on war ships in World War II. Computer-aided targeting effectively moved the gun-sighting crew from high above the rolling deck of the ship and the lattice mast to the innermost compartments of the ship's hull. This eliminated much of the danger associated with being exposed to enemy fire. The elimination of the lattice mast, mounted observation area also made night fighting possible.