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Yachtsnet's archive of boat details and pictures

The following information and photographs are displayed as a service to anyone researching yacht types. HOWEVER THE PHOTOGRAPHS AND TEXT ARE COVERED BY COPYRIGHT, AND MAY NOT BE REPRODUCED WITHOUT THE PERMISSION OF YACHTSNET LTD. Details and photographs are normally based on one specific yacht, but could be a compilation. No reliance should be placed on other yachts of the same class being identical.  Where common variations exist, we have endeavoured to indicate this in these archive details.

Harrison Butler 'Z' 4-tonner

Brief Notes


Alfred Lockhart Ltd.

The 'Z' 4-tonner was one of the first "production yachts", being marketed by Capt. O. M. Watts of London in a choice of layouts. A genuine classic yacht, they are very attractive small cruisers.

Length OA

21' 9"

Sail Area

260 sq ft

Length WL

19' 0"




7' 2"




4' 0"




7,400 lbs

Engine type

originally Watermota or Stuart Turner petrol engines


2,700 lbs

Engine bhp

4 - 6

Keel type

Long keel

Complete with engine (a choice of a 6hp Watermota petrol-paraffin or a 4 hp two-stroke Stuart Turner petrol), anchor & chain, a suit of cotton sails, and a standard inventory including warps, coir fenders, paraffin anchor and cabin lamps, spring berth mattresses and a deck mop (with handle), the delivery price launched and ready to sail in 1939 was £297.

Two lists of "optional extras" were quoted for, the "Normal Cruising Equipment" list including items such as lead and line, salt water soap, and kapok lifebelts. The "De Luxe" list included clock, barometer, battery operated wireless and waterproof cotton sleeping bags lined with best quality camel hair.

The Z4 was designed by Dr. Thomas Harrison Butler, MA, DM(Oxon), FRCS (Eng-Honorary), AINA (Honorary), who was born on March 19th 1871. Whilst his profession was an ophthalmologist, he was also an amateur yachtsman and self-taught yacht designer, and a strong believer in the use of the "metacentric shelf formula" to achieve good balance and handling under sail. This theory, the "metacentric shelf" theory, is now regarded as irrelevant, but when applied by Dr. Harrison Butler did produce famously sweet-handling yachts, in an age when the norm was to have heavy weather helm when reaching and heeled. Harrison Butler died in 1945.

The 'Z' four-tonner was one of his best-known designs, this being a production version of his 'Zyklon' design, of which several examples were built The 'Zyklons' are almost identical to the 'Z' 4-tonners, of which at least 52 were built. The "four ton" description being Thames Tonnage, a measure of a ships size calculated by measurements, derived originally from estimating the number of 'tun' barrels of wine a ship could carry. She actually displaces 3.3 tons. The hull lines are similar to those of a Falmouth Quay Punt, although the original Falmouth Quay Punts were bigger, and would be gaff-rigged yawls

The yachts were sold in three versions, an open half-decker, this "standard" version, with conventional coachroof, and a version with the coachroof extended to the hull sides, to give extra space below. Construction is of pitch-pine planking on oak and elm frames and keelson, with steel reinforcing ring frames and knees. Above the waterline the carvel planking seams are splined and glued, and conventionally caulked below the waterline. The original deck planking has been retained, but where originally it would have been (supposedly) leak-proofed with canvas and paint covering, it has on this yacht now been rebuilt with epoxy-glass sheathing over plywood.

Yachts seen here are no longer for sale - the data is online as a free information service for buyers researching boat types. THE PHOTOGRAPHS ARE COVERED BY COPYRIGHT, AND MAY NOT BE REPRODUCED WITHOUT THE PERMISSION OF YACHTSNET LTD.

Go to our brokerage section for boats currently for sale

The pictures here are of an exceptionally well kept example, with a very original layout, except for having had a small modern diesel installed

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