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3 DrumsLoads of steam

Type: Multi Fuel, 3 drum Tube boiler (aka Yarrow)
Overall Length: 8 in
No. of cross tubes:
Width: 8 in.
6 in.
11 in.
Height to top of funnel:
17 1/2 in.
Working Pressure:
80-100 P.s.i.
Availability 1989-2006

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The "Mendip" water tube boiler is of the Blackstaff design and is specifically aimed at the model engineer with its authentic appearance. This boiler can be fired from a variety of fuels and is supplied with a specifically designed gas burner.
A feature of the Mendip is that no artificial draught is required to light and steam the boiler. Steam is available within four minutes of lighting up.


Copper three drum water tube boiler pressure tested the factory. Integral gas burner, copper chimney, water gauge, safety valve, steam stop valve, pressure gauge and syphon.


Possibly the best Stuart boiler for larger engines, indications are that it is based on the Cheddar models Pegasus boiler. The design, similar to the Yarrow design is called a Blackstaff,The main difference is the use of straight connecting pipes in the Yarrow and coiled pipes in the Blackstaff. The Yarrow is more common in full size use where the many straight tube allow for fast water circulation, for models the curved tube design allow for many less tubes tu get a similar effect. It consists of 3 drums mounted 1 at the top above the heat and one each side. The top drum is connected to both the lower drums in an inverted V formation. There are several pipes connecting the drums, each is coiled to increase surface area. The extensive surface are in contact with the flame results in very fast run up to pressure. Water is heated in the coiled tubes and rises into the head drum, this suck water down to the feeder drums via the straight pipes. This means that strong circulating currents form, ensuring that all the water is subjected to the heat in the coiled pipes. Heat source for the Mendip was by a choice of 3 methods, a gas burner was available as well as a grate for use with wood or coal. A small dome is fitted to the top for drier steam.

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Picture of the Boiler itself. (Thanks to Hubert Paulus for this pic and dates info.)

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Mendip Boiler with Chimney.

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A nice steam launch with Mendip boiler & Stuart Compound Launch engine.

Video Of mendip


Accessory Water Tank


Mendip Gas Burner

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