March 9, 2020

Steam Launch Update #9

Capt. Nat’s engines and boilers.

Before we move into construction of the launch and the power plant that goes into it, I thought it would be helpful to discuss Capt. Nat’s engines and boilers.

Boilers seem to be the first focus of books about Capt. Nat so let’s start there.  

From 1868 – 1874 the Herreshoff family installed upright boilers in their steamers (boats #1 -13) 

But in 1893 James Herreshoff invented the coil boiler which brother Nat soon improved and these would go in craft from 1874 – 1884 (boats #14-100.) These were an important improvement for launch and smaller yachts and gained several strong proponents in the naval establishment, but with a single long beehive shaped coil they were expensive to  build and replace.

So the Herreshoff’s designed a Square Boiler which simplified manufacture and repair. (These would go in boats #100 – 193 from 1884 -1896). But as Herreshoff began making large high-speed (racing) yachts and torpedo boats, Capt Nat found they could not produce sufficient steam in dynamic high-speed regimes.

Beginning with USS Cushing (TB-1)(1890) Herreshoff was forced to use Thorneycroft three drum boilers for TB and largest yachts. In 1895 he had his own design of three drum, bent tube boiler installed in USS DuPont (1895) and shortly thereafter in launches and yachts until the end of the steam era. (Thorneycroft (UK) and Normand (FR) boilers built upon work of DuMond who tried to build a light-weight steam system for aircraft. These would become the universal standard marine boiler.)

For more details see the attached slides. Download slides or click the slides below: