Navy lighterage pontoon

The Navy Lighterage pontoon (NLP) was a type of pontoon developed in World War II by the US Navy and used by naval construction teams (Seabees) and specialized US Army combat engineers, on invasion beaches and shallow harbors or harbors where the facilities had been destroyed or did not exit, to construct docks, wharfs, barges, floating cranes and other floating units.

The concept of NLPs was first discussed in 1935, but it was in 1940 that the US Navy took the idea seriously and began development, with testing taking place just before the US entered World War II. The Dieppe Raid in early 1942 showed that the idea of seizing a port in the face of modern coastal defences was either costly or impossible. The US Navy saw the vital importance of being able to build their own port facilities and to deploy naval construction teams trained and dedicated for just that role. The US Army soon followed with their own units.

Construction
The NLPs were constructed of welded steel flotation units that were assembled like children's wooden block toys, connected by special angle-iron pieces, called stringers. The flotation boxes and stringers were held together by special iron wedge pins. The flotation blocks came in two types: The principal type of unit was a 5 x rectangular prism; the majority of NLPs were constructed using these. The second type was similar but curved upward on one side, and these boxes were used to make bows on the front of NLP barges when required.