Some government boats have jet drives. In this post from early September 2014, the smaller vessel had jet drive, whereas the larger one–propellers, although I can find no info about , eg, their diameter.
The other day in the East River I encountered FDNY’s newest (?) vessel, William M. Feehan. Click here for Feehan‘s dedication in the sixth boro.
Feehan‘s 3450 hp, generated by three Caterpillar C-18 engines, gets propelled by three HJ 403 Hamilton jets.
Speeds are slightly faster in fresh water, but both fresh and salt water need to be in liquid state.
USS Little Rock‘s 96,000 hp are to no avail when water converts to solid state, even with just some chunks of solid, because of the otherwise highly desirable waterjets. For complete specs on USS Little Rock LCS-9, click here.
The photo above comes via Marc Piché and was taken by René Beauchamp. All others by Will Van Dorp.
tugster: a waterblog 
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February 18, 2018 at 2:15 pm
Lee Rust
‘Willam M. Feehan’… looks like the builder took a lot of cues from Phil Bolger’s square boat designs.
‘Little Rock’… aside from the sentry box on the foredeck and the open hatch there doesn’t seem to be much activity aboard on the day of the photo. No tracks in the snow around the boarding ramp. I wonder if the Navy sent the crew home for the winter.
February 18, 2018 at 7:38 pm
Les Sonnenmark
Note that for slow, cruising speeds LITTLE ROCK can be propelled by her diesels alone with about 17,000 hp; at higher speeds with her gas turbines alone with about 96,000 hp; and at highest, sprint speeds with diesels and gas turbines combined at nearly 114,000 hp through all four waterjets.
February 19, 2018 at 12:22 pm
Lee Rust
That’s a lot of HP! At the sprint speed of 52 mph, the fuel consumption for a vessel that size might well be measured in gallons per foot rather than gallons per mile.