It seems as if Herreshoff boilers lead the way in innovation in the launch and yacht segment until the Europeans (Thorneycroft and Normand) developed the three- drum, bent tube boilers (Note James Herreshoff's 1973 coil boiler innovation preceded John and Nat's formation of Herreshoff Manufacturing Company in 1978.)

But in the case of steam engines, Capt. Nat remained at the forefront of engine design for marine launches and yachts until the advent of automobiles and development of sufficiently powerful and reliable internal combustion engines which would replace steam powerplants in yachts and launches. In fact, it seems as if he turned his focus from boilers towards engine development in the mid 1880's to mid 1890's.

Coincidently with  this emerging disruptive technology, the British yacht Turbinia demonstrated higher speed operations with steam turbine driven propulsion. (Required development of super cavitating propellers.)

Thus in a very short period of time, internal combustion (gasoline and diesel) replaced steam on launches, yachts, and racing craft and steam turbine propulsion would replace steam piston propulsion for naval warships. (see development of destroyers and dreadnaughts in the first decade of 1900's)

Herreshoff would develop single and compound engines of many sizes, triple compound engines, and "steeple" engines with single and two-cylinder low pressure stages placed over the other two cylinders. He would even develop a four stage engine before settling back upon more reliable triple expansion engines.

For more details see attached images below. Or download the slides.