How many principal types of salvage are currently utilized in the Navy?

The current principal types of salvage utilized in the Navy are four, which is why this answer is recognized as correct. Salvage operations are crucial for recovering disabled ships, cargo, and other assets that may be at risk or obstruct navigation. The four principal types typically include:

1. Salvage by Lifting: This involves raising the sunken vessel or cargo from the seabed to the surface, often employing cranes or other machinery.

2. Salvage by Refloating: Refloating deals with getting a grounded ship back into the water and seaworthy. This might involve lightering operations (removing cargo) or using pumps to remove water from the vessel.

3. Salvage by Wreck Removal: This type focuses on safely removing a wreck from a navigational channel or area to ensure safety and prevent environmental hazards.

4. Salvage by Recovery: This pertains to recovering valuable cargo or items from a sunken vessel without raising the entire ship.

Understanding these four types is essential for personnel involved in salvage operations, as each type requires different techniques, equipment, and expertise tailored to the specific circumstances of the salvage scenario.