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W J Yarwood (No. 193) - Marine Engine

A two cylinder, inverted, vertical, compound marine engine. Built in 1937 by W J Yarwood & Sons of Northwich, Cheshire. Originally installed in a grab-hopper dredger and buoy tender named 'Seiont II'.  It saw service in and around Caernarfon harbour and in the Menai Strait (between North Wales and Anglesey).

W J Yarwood made only 232 steam engines (the last in 1957), of which three are still in existence in England - Nos. 193; 220; 221, and probably one in Norway - No. 208.

No. 193 is the oldest one, and is the only one steaming in this country.

The dredger, 'Seiont II', built by W J Yarwood in Yard No.604, was launched in Sept 1937. It was completed and handed over to The Caernarfon Harbour Trust in Nov 1937.

It ceased active work in 1978, after which it was sold several times:-
1983, July 20: to The National Museum of Wales for preservation at Caernarfon.
1990, July 26: to Seiont II Maritime Trust/Caernarfon Maritime Museum.
1998, Feb: at Port Dinorwig (Y Felinheli) and then to various people.
1999, July: the vessel was broken up at Port Penrhyn. The engine was saved and stored, outdoors, at Port Dinorwig.

2002, April 17: the engine was delivered to Markham Grange Steam Museum, on loan for 4 years.
2005, Jan 1: first steaming of the engine at Markham Grange.
2006 the loan period extended until April 2009.

The engine is currently on loan from 'Seiont II' Maritime Trust (Caernarfon Maritime Museum),

Ref CAEST 9932.


Technical Details

Type of Engine:-

Builder & Year:-

Horse Power:-

Cylinder Sizes:-





Other Information:-

Two cylinder, inverted vertical, compound

W J Yarwood, Northwich, Cheshire

190 HP at 135 psi steam pressure

High Pressure (HP) is 10.5 ins diameter
Low Pressure (LP) is 21 ins diameter

16 ins.

The HP cylinder is controlled by a sliding piston valve and the LP by a conventional slide valve.



There are two eccentrics per valve coupled to Howe-Stephenson
linkage, to control forward and astern direction.
Ahead rotation is clockwise when looking from the propeller end.

The engine has a set of three pumps driven by double beams from the HP cross-head ie:-
a bilge pump; an Edwards air pump, a boiler feed pump.

The condenser and hotwell no longer exist.
The thrust of the propeller was taken by a Michell tilting pad thrust bearing, mounted next to the output coupling.
The thrust bearing is on display at the museum.