Roger Calvert's Steamboat Page

SL Senta

Senta is based on a Flying Dutchman sailing boat shell, never fitted out for sailing. She is built of cold-moulded plywood, sheathed with glass fibre. She was first fitted out for steam in 1976; since then there have been many incremental changes, most of them improvements.

Overall length:	6.1 m	20 ft
Beam:	1.8 m	5 ft 9 in
Draught:	0.5 m	20 in
Air draught:	1.5 m	5 ft

Senta on the Stratford Avon 1979

Senta on the Beaulieu River, July 2011 (Photo: Mike Bell)

Technical details:

For many years, Senta had a non-condensing "puffer" plant, using river water if fresh, otherwise an on-board tank. In 2002, the plant was converted to be either condensing or puffing, by changing a couple of valves. In 2003, an air pump was fitted, and the puffing facility removed.

Boiler: Vertical centre drum 8 coil (Ofeldt type) copper boiler, approximately 1 sq m (10 sq ft) heating area; built in 1993, but barely used until installed in Senta in June 2009. This replaced the previous vertical cross-tube boiler, fitted 1999 (itself replacing the second of two Merryweather 'A' boilers) which showed signs of trouble on an outing on the River Wey in May 2009, later inspection showing a hole from the water space to the centre flue at about the water level. It was not practical to repair this, so the current boiler was obtained and fitted.

Maximum operating pressure 7 bar (100 lb/sq in). Solid fuel (wood and coal).

Engine: Stuart Turner 5A, double acting single cylinder, 58 mm (2¼ in) bore by 51 mm (2 in) stroke, Stephenson's link reverse gear. Normal operating speed 400 to 500 rev/min. (Similar to the animation below.)

Condenser: 2 copper tubes approximately 16 mm (5/8 in) diameter, 1.2 m (4 ft) long, under the after part of the hull.

Transmission: 2:1 bevel gear step down to the propeller shaft; universal joints, thrust block at stern gland. Propeller 36 cm (14 in) diameter by 51 cm (20 in) pitch.

Auxiliaries: Prop-shaft driven feed pump with air pump on the same eccentric; hand feed pump; funnel blower; whistle; bilge ejector; Windermere kettle; electronic tachometer (converted from a bicycle speedometer).

Summer 2021: an automatic feedpump bypass was fitted, with a float valve in the hot well.

The float valve in the hot well (photo Roger Calvert)

Further details of Senta and her history can be found in her entry in the Steam Boat Register.

Senta had a complete hull overhaul and paint during the winter 2008-09. The result is excellent - see the picture on the right.

When the new boiler was fitted in 2009, the previous wooden boiler casing did not fit, so for a while the finish was the plain steel casing. Over the next year, though, vertical wooden stave cladding has been added.

Senta on Windermere, September 2012 (photo Richard Bartrop)

Senta January 2013 (photo: Roger Calvert)

Summer 2024: a damper has been fitted over the top of the funnel to help suppress the fire while waiting e.g. over lunch or in a lock. Mark 1, which flipped up vertically was unsuccessful - it diverted a head-wind down the funnel. Mark 2 (right) which rotates away horizontally is more successful.

Heavy weather!

Before the heavy snowfall in January 2013, the canopy was supporting the tarpaulin. Major repairs to the canopy structure were needed!

This has been resolved in January 2015 by the provision of a splendid new boat house!

Books of interest to steamboaters

Anybody interested in Steam Boats should be a member of the Steam Boat Association of Great Britain (SBA). They publish a quarterly magazine The Funnel and their web site has lots of pictures of boats and information about the Association.

The SBA also maintain the Steamboat Register, which contains detailed information about more than 800 steam boats in the UK and abroad.

The Windermere Steamboat Museum has perhaps the best single collection of steamboats in the UK.
It was closed for many years for major redevelopment work and conservation work on the boats.

It reopened in 2019 and is now operated by the Lakeland Arts Trust Lakeland Arts Logo

. It has been renamed as the Windermere Jetty Museum.

Until recently, SL Shamrock was the only traditional Windermere steam launch currrently running, but has now been joined by her sister ship SL Osprey, restored by Windermere Jetty. SL Shamrock is owned and operated by the Shamrock Trust, registered charity no 1136535.

The history of Shamrock has recently been published as The Story of Shamrock.

Shamrock at the 2014 Windermere Boat parade (photo: Les Edwards)

The International Steamboat Society publishes a comprehensive magazine Steamboating with information about steamboating in North America.

See also Rainer Radow's Steam Boat Page:

A technically sound but accessible introduction to the theory and practise of small scale steam plant. Ideal for the model engineer or preservationist: 1991, ISBN 0 951360 1 1, paperback, 130 pages

A compilation of articles from The Funnel, the magazine of the Steam Boat Association of Great Britain covering practical matters ranging from designing boilers to tying knots: 1994, ISBN 0 9513620 4 6, paperback, 175 pages. This book is still available, at a reduced price, following the publication of a new edition by the Steam Boat Association.

Tables, in both British Thermal and SI units, of the properties of steam over the range of interest for preserved and reproduction steam engines, and other relevant data: 1991, ISBN 0 9513620 2 X, booklet, 12 pages.

The three above titles and 'The Story of Shamrock' may be obtained direct from the publisher.