Stuart Roy
Naval Architect & Consultant

Fellow of the Royal Institution of Naval Architects
Chartered Engineer


© Stuart Roy 2015
70ft Steel Ketch “Calypso”
A tribute design to Joshua Slocum’s famous “Spray”
In the spring of 1892, Capt. Joshua Slocum was given the hulk of an old Delaware oysterman named “Spray”, believed to date from around 1800, which had been left propped up in a field in Massachusetts for 7 years. Over the next 13 months, Slocum rebuilt the 36’-9” (11.2m) boat plank-by-plank including a new oak keel and spruce mast. The only significant change to the form of the original working sailboat was an increase in the height of the freeboard.

In April 1895, Slocum set off in Spray to sail single-handed around the world.  This turned out to be an eventful trip, which he completed in June 1898 having sailed more than 46000 miles. His vivid account of the voyage was published in 1899 as a series of articles and also in 1900 as the famous book “Sailing Alone Around the World”. (Penguin Classics ISBN: 978014-043736-2)

Throughout the book, Slocum praises the seaworthiness and sailing qualities of Spray, in particular her ability to hold a course at sea, even when running before the wind. Fortunately for naval architects, clues to the secrets of Spray’s attributes can be found by analysing and studying her hull form, as Slocum generously provided drawings of the Lines Plan, Body Sections and Sail Plan in Appendix 1 of his book, as well as plenty of first-hand description of the vessel’s construction, fit-out, rig handling and practices he employed at sea. This information has enabled several Spray replicas to be built over the years as well as hundreds of Spray copies, all hoping to capture the favourable qualities that Slocum described so convincingly.

Although almost twice the size of Spray, “Calypso” is unashamedly a tribute design to Slocum’s yacht. Visually she shares many of Spray’s features, such as the clipper bow with integral bowsprit, long shallow keel, central box-shaped deck saloon, subdivided deck area and a two-masted rig. She is intended to be a comfortable, spacious and very practical ocean cruiser.

Starting with the concept and outline general arrangement sketches provided by the client in 2005/6, the design of Calypso involved a detailed study of the original Spray’s hull form to investigate and establish the optimum choices for the hull form coefficients, ratios, body section shapes, waterline angle of entrance, angle & length of run and other characteristics of hull shape. The lines plan developed as a result of these studies still remains remarkably close to that of Spray. It also remained largely unchanged after extensive checking by computer of the large angle stability, damage survivability, sailing performance, rig loading, and powering. As with Slocum’s re-building, the freeboard was raised, in this case to provide an owner’s suite aft.

When the lines plan and scantling section were complete, the design was re-processed by Jim Moore Design, so that it could be assembled from a kit of steel parts using only simple plate rolling without complex forming techniques. A steel kit was then ordered from Wales and assembled during 2007 by Brian Newbury’s team at Newhaven in Sussex.  After launching, the yacht was motored under its own power to Cowes for fitting out, rigging and trials during 2008.  

In her first year in commission (2009) Calypso sailed from Cowes to her cruising base at Kip Marina in Scotland, coping well with rough conditions in the Irish Sea and completing the passage at an average speed of around 8 knots. As hoped she demonstrates Spray’s inherent ability to maintain a course, yet turns well when required using the large aerofoil-section rudder. The modern ketch rig is versatile and easy to handle. The twin-wheeled cockpit is very effective. At sea she likes to power along in a good blow, but then exhibits little heel and an easy motion.          
For more about Calypso,
please see
Spray 1895
Calypso 2007