Chris McMullen’s Herreshoff Steam Launch


Back in 2014 we did a great story on the 34’ replica Herreshoff steam launch that Chris McMullen is building in his spare time, back then it had been 30 years in the making and now its approx 37 years, but when I called in last week, there had been some significant progress. Have a read of the 2014 WW stories to take in the magnitude of the project – everything , including the steam engine built by hand. When Chris started the project he didn’t have the benefit of the internet or google to help but in recent years he has uncovered numerous old photos that have helped with the project.

Some Background: Herreshoff Manufacturing Co build # 263 was a steam launch called “Cassandra Junior” and Chris believes that is the steam launch shown astern of beautiful 287′ S.Y. “Cassandra” in the photo below, she was stowed on the port side launch of the yacht. The Herreshoff Manufacturing Co built approximately twenty of this type of steam launch in the 27f’ > 34′. The H.M.C build # 227 – Vapor, refer photo below, was 30′ and built for the Steam Yacht “Yacoma” but Chris understands she was never used on that ship. A model of “Yacoma” at Mystic Sea Port Museum shows a steam launch but Chris assumes the ship had a more convenient modern motor boat.  

The last b/w photo below is the tender for the steam yacht ‘Wanderer’  (photo below) called ‘Wanderer Junior’. She was Herreshoff build # 270, she is American and measures 27′ 11″. Built 1909. In the back ground of the photo is the ‘Ida Lewis Yacht Club’.

The engine on Chris’s launch has been run and currently getting a tidy up before being re-installed.
The main reason for the visit was to get an update on the restoration of Haunui, the 1948 Colin Wild launch – happening nearby – check in one Wednesday for that story. I took Jamie Hudson, skipper of Lady Crossley , an almost sister ship, built one year apart, fascinating to get Jamie’s view on the two boats.


H.M.C work shop – unidentified steam launch. 
Cassandra, with Cassandra Junior astern
Vapor with her late owner Jon Martin. Taken late 1960’s
Wanderer Junior – built 1909

IT FLOATS – On 11-11-2021, on the upper reaches of the Tamaki River, Chris McMullen ticked off a rather large item on his to-do list. He launched his N G Herreshoff design Steam Launch. Chris commented that it was just a floatation trial, and that the design floated absolutely level. In the photos below we see her with all her machinery but with no fuel or water. Chris commented that for years he has had the greatest respect for the late Nathanial  Herreshoff and devoted over thirty years (on and off) of his life to the project and is as keen as ever to get it under steam power. You can see, at the link below, the only image Chris has found of the original “Cassandra Junior” see

UPDATE 04-01-2022 – The below photos were from a shed visit in early Dec 2021, post the above water line test 🙂 click to enlarge

The Best of Colin Wild + Herreshoff Steam Launch

The Best of Colin Wild + Herreshoff Steam Launch
The top two photos of the Brooke families 1927 Colin Wild launch – Linda comes to us via Mitchell Hutchings fb ex the Williamson Family Collection. Linda at the time was moored at Herald Island.

The bottom photo I took today of Wirihana tucked up in Chris McMullen’s shed for her winter TLC. Wirihana is another of Wild’s big motorboats, built in 1933.

It was great to see that CMcM’s Herreshoff steam launch (below) is coming along – engine installed 🙂

Chris McMullen Herreshoff Steam Launch – Part 2 (the engine)

The building of a replica 1898 Nathanael Herreshoff triple expansion steam engine – as told by Chris McMullen.

CMcM SteamLaunch AH6

The Herreshoff engine is a triple expansion type with cylinders 3-1/2” x 5”x 8” with a 4-1/2” stroke. It is a smaller version of that depicted in the L Francis Herreshoff book ‘The Wizard Of Bristol’ page 228.

The engine is very different to what the textbooks on the subject show. Everything designed by Nathanael Herreshoff seems to be that way. He certainly never copied traditional thinking but worked it out for him self.

Those interested may notice the two crankshafts gear driven one to one. The right hand one drives the piston valves. Going astern is effected by sliding bush or sleeve within the driven gear activated by a lever, this rotates the valve C/S to a new position. The bush, gear and shaft required machining male and female three start threads, left and right hand 8” pitch!  Not easy. The threads have / had to be cut on a planer using a dividing head coupled to the motion. Modern cars use a camshaft driven by a timing belt, similar to Herreshoff but remember this engine was designed in 1898!  The engine is very short to allow the crankshaft to be supported by two bearings and also to prevent loss of heat as the exhaust steam travels from one cylinder to the next, thus trying to reduce pressure loss.

If you look at the image of the crankshaft casting (below) you will notice the overhung balance weights. Notice the lack of material in the web between the second and third journal. The crank can’t be ground and there is no easy way to machine the metal designed to be eliminated by casting.  Casting this crank was a mission in SG iron. To cast it in steel (with 1/4” to the foot possible contraction) is going to be more difficult to achieve the correct length.

H.M.C.O had an outside foundry cast their steel but I notice in reading a recent article on Herreshoff Anchors they did have problems with their steel castings.

The base of the engine is a bronze casting to hold oil. The engine max revs are about 700 so the engine will have to be enclosed or throw oil everywhere.

There are good drawings available for this engine but no tolerances are given. I guess the fitters knew what was required. The original drawings were coloured to show the different materials, as was normal drafting practice.  The prints I got were black and white and difficult to read. No layers as in CAD drawing.

The Boiler is a three-drum type with curved tubes. It is similar to a Yarrow Type boiler. All the circulation is achieved in the tubes, the outer tubes being cooler than the inner. Once the circulation starts it continues. This was proven by Yarrows experiment in the early 1900’s. So Herreshoff and Yarrow, an ocean apart, came to similar conclusions. The upper drum of the boiler is 8“ OD, the lower drums 4-1/2” all with 5/16” wall. The 1/2“ tubes are expanded. Not easy to do up a tube just over 4” ID.

The boiler was built under survey. The working pressure is 250 PSI.

There are no pumps on the engine. The boiler is fed and the cooled exhaust condensate is removed for reuse by an independent steam driven combined feed and air pump. These pumps were the only item on the launch not made in house by H.M.C.O.  There were no drawings of these Marsh Pumps made by The American Steam Pump Co., Battle Creek Mitch. I copied mine from ‘Vapo’, an incredibly clever but simple pump with two moving parts but very difficult to manufacture.

I should add there has been no fabrication. Everything has been cast in iron or bronze.

Again this interesting project has been done for no other reason than for my own personal satisfaction.  I guess Prof. Evers Burtner’s comments (see copy of magazine article below), I quote “It is too bad that this engine is so complicated that amateurs would not be tempted to build one of their own”, was red rag to a bull.

To view part one i.e. the boat click here

Click Any Image / Photo Below To Enlarge