Currently, the U.S. Navy's submarine fleet consists of 29 Los Angeles-class fast attack submarines and 18 Ohio-class nuclear ballistic missile submarines. These submarines are part of the nuclear land, sea, and air triad that defends the United States from nuclear attack.

The idea of the triad is that no aggressor could knock out all three at the same time, which leaves open the capability to mount a corresponding counterattack if necessary. The most difficult part of the triad to attack is the submarine element. Submarines, by their very nature, are meant to be silent, deadly, and more difficult to monitor, as they are designed to avoid detection as much as possible.

Photo: YouTube/Fluctus

The Columbia-class submarines will be bigger yet than the already huge Ohio-class submarines. They are going to be 560' in length and will have a 42' beam. They will be able to keep up a 29-mph speed underwater. They will be capable of reaching depths of 800 feet and will carry a nuclear fuel supply that will carry them through their planned lifetime. I will explain this comment below.

These subs will cost somewhere in the area of $7.2 billion per boat and will have 16 missile tubes for the most advanced Trident missiles. The first one is due to enter the fleet within the next couple of years and is expected to be in service until 2084.

Photo: YouTube/Fluctus

The Columbia-class subs will include five improvements over the Ohio-class subs that they will eventually replace. These improvements include:

A better sonar system that will need less maintenance, as it will be designed to last for the lifetime of each boat. The Ohio-class sonar system must be replaced every ten years.

Photo: YouTube/Fluctus

They will have improved nuclear reactors that, again, are designed to last for the boat's lifetime. The Ohio-class boats have to have reactor replacements at the mid-point of their lifetimes. This means that the Columbia-class boats will be able to spend more time at sea and less time in dry docks. They will be able to take on more missions as well.

The Columbia-class subs will have a new drive system as well. It will be an electric drive propulsion system that will make it even quieter than the Los Angeles and the Ohio-class subs. They will have improved control stick and auto-pilot systems.

Photo: YouTube/Fluctus

The communications systems will also be new and improved. They will no longer have a periscope system but a camera mast. And finally, they will have extensive design improvements in their hulls and in the machinery of their drive systems that will reduce mechanical vibrations and thereby reduce even more their "signature" for potential enemy detection.

The plan is to produce 14 of these new Columbia-class nuclear-powered submarines. They will eventually replace the 18 Ohio-class boats currently in the fleet.

This video will give you a sense of what these submarines will look like and what they are capable of. To use an old WWII movie title, these new fast and powerful Columbia-class submarines will, "Run Silent and Run Deep" in a way they have never before.

https://www.youtube.com/watch?v=KVZ2gai47bQ