The USNS Gilliss - top, and USNS Lynch, - center, small vessels of 210' x 37' both sisters to the De Steiger - above. A dozen or so were built, and they were strong ships...not one lost in hurricanes, or typhoons. Real work horses in oceanography...covered the globe.
For power, they were outfitted with "just enough" - Catapillar large-truck engines, rated at a thousand horse-power...if that, turning a single constant pitch, variable ( pitch varies - decreasing, from hub to tip of blade ) pitch screw ten feet in diameter. They were not "controllable pitch", nor "cycloidal" as I have seen in some accounts. The Wood's Hole vessel "Knorr" had those - cycloidal propellors...one forward, one aft. The catarmaran USNS Hayes had controllable pitch propellors.
For station keeping, the Gilliss had an omni directional bow thruster in the fashion of an outboard motor - a propellor in a "Kort nozzle" that lowered below the bottom of the ship. It was forward, and was of one-hundred horse-power. The Lynch had a more complex set-up using "water jets" - vanes at the sides of the vessel directing jet output. Whether the other AGORs employed other means, like tunnel thrusters, I don't know, but it's possible. The larger AGSs like the Kane, Wilkes, Wyman, and Bent varied in thrusters - the Kane having a similar device to the Gilliss'; the Wilkes having a tunnel thruster forward, the Wyman having only an "Active Rudder" - a propellor mounted on the main rudder that could be put over seventy-degrees port, or starboard. I don't know about the Bent.
Charlie Taylor - Chief Engr. called them "Fire Cracker Engines". He also went to far as to say he doubted if he got eight-hundred, and fifty horse-power out of them. "Might just as well replace the engines with large outboards, and use the engine spaces for store-rooms."
In the photos below, taken while on the Gilliss, Lynch, and Gilliss was working together engaged in underwater sound research. While Lynch stayed tethered to Spar, Gilliss would run off some miles, and throw explosives into the water. On this occasion, the ships straddled the Gulf Stream, and the idea was to see how sound waves were deflected - if any, as they went through the Gulf Stream. See my story Here.
My only claim to having been on the De Steiger is when I sat on her dockside for a month in San Diego while the contractor looked for a Chief Mate. I had been retired, and got this pleading request at a time when I thought a respite from retirement would be nice. It was alright, but did remind me of why I did retire in the first place. It took another month on the Lynch, delivering her to Norfolk for lay-up to finally remind me that I retired because it was time to. That was ten years ago, and I've remained content since to stay retired. The party's over...or maybe it begun. Whatever, thirty-seven years at sea was enough.