The amphibious ship Makin Island, LHD-8, differs from her sisters in having a hybrid engine system consisting of both a pair of GE LM2500 gas turbines and a pair of electromotors which draw their power from six diesel generators. Propulsion is split between the gas turbines and the diesel generators. At slow speeds, less than 12 kts or so, the diesel electric propulsion is used and allows significant fuel savings. At higher speeds, the gas turbines can operate near their peak efficiency. The Navy estimates fuel savings of $250M over the life of the ship.
By comparison, the
’s sister ships and many other conventional Navy ships use standard steam turbines. Smaller ships such as the Burkes use only gas turbines. Makin Island
Eliminating steam boilers allows for faster startup and reduced manning requirements, among other benefits. Additionally, the gas turbines use the same fuel, JP-5, that aircraft use, thus simplifying the fuel storage situation.
Note that there is nothing inherently new about hybrid engine technology, gas turbines, or electric drives. I assume that the motivation for the Navy’s switch to hybrid propulsion is due to a desire for fuel cost savings. I hope that we aren’t giving up combat performance to obtain cost savings. I don’t know enough about the propulsion technology, new or old, to be able to assess any impact on combat capabilities.
class, LHA-6, will also be fitted with a hybrid propulsion system and it would seem that all future amphibious ships will have some variation of this technology. America
Assuming that there are no combat drawbacks to the propulsion arrangement, this would seem to be a reasonable development. It’s good to see the Navy do something right!