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Sold: 21ft. Harrison Butler ‘Z’ Four-Tonner Sloop – 1938 – Immaculate Example – Lying: South Coast



Boat Details

Overall Length: 21ft 9ins
Waterline: 19ft
Beam: 7ft 2ins
Draught: 4ft
Displacement: 3.3 Tonnes
Engine: 9hp Yanmar 1GM10
Berths: Two Berths
Sail: 260 sq.ft Bermudian Sloop Rig
Designer: Dr. T Harrison Butler
Builder: Alfred Lockhart Marine
Year Built: 1938
Location: South Coast


The Zyklon design first drawn by Dr T Harrison Butler in the mid-1920’s has become an icon of pocket cruising yachts.

In 1937 THB was approached by Captain O M Watts to produce a weatherly 4 tonner which could be built on a production-line basis, the first of it’s kind in the UK. THB revised his earlier Cyclone design to produce the Zyklon Class. Captain Watts approached the old established Brentford joiners and timber merchants Alfred Lockhart and a factory was set-up in late 1937 where the first example was built. The design was marketed as the ‘Z Four – Tonner’ and can be distinguished by the letter Z on the stemhead.

In 1938, the first full year of production fourteen examples were completed. In order to complete the yachts quickly and economically, an efficient assembly and costing system were used. The work was divided into twelve operations using pre-made parts and sub-assemblies taken into stock. The construction is novel, the hulls were built upside down on a steel mould taking four men a week to plank. A six week delivery for all Z4 orders was quoted, the price in 1938 being £297, rising to £339 in 1939.

By the end of 1939 forty-eight ‘Z’ Four Tonners had been built and sold and the Zyklon Design was gaining a superb reputation with Yachting Monthly featuring extended voyages. Had the Second World War not intervened many more examples would have been built, although several other boatyards also built examples of the Zyklon design.

Captain Watts had plans to build and market other THB designs however after the war Lockharts were engaged with joinery work to repair bomb-damaged houses in London and materials were scarce for yacht building.

Harrison Butler was a strong believer in the ‘metacentric shelf formula’ to achieve good balance and handling under sail. The theory held that as a yacht heels under sail, its balance will depend on the immersed form of the hull, with different sections exerting varying degrees of buoyancy and aft sections possibly being more buoyant than forward sections. Metacentric shelf analysis plots the shifts in the varying buoyancies as a net value to windward or leeward and serves as a guide to achieving equal buoyancy in the dissimilar ends of a design. The work can now be done by computer, but when it was applied by the brain, hand and eye of Dr Harrison Butler it produced famously sweet-handling boats, in the age of heavy weather helm.
In the days before computers, Harrison Butler was known to cut out paper cross sections of his hulls in order to calculate lines of symmetry and centres of mass. Boats built to his designs are much sought-after and owners eligible to join the Harrison Butler Association of approx 200 members worldwide. On the South-Coast of England, there is a growing stronghold of more than a dozen Harrison Butler designed yachts who meet up on a frequent basis in the Solent or Isle of Wight.

Carvel larch planked hull, copper fastened to steam-bent timbers. Cast iron 1.25-ton iron cast keel. Teak brightwork and cockpit.

Two berth cabin. Galley having single burner Origo spirit stove. Restored Baby Blake heads. Gimballed oil lamp. 12v lighting.

9hp Yanmar 1GM10 diesel, professional serviced annually.

Hull professionally painted and antifouled annually.

Offset bronze propeller, new stern gland and shaft log (2018). Stainless steel fuel tank.

Fractional Bermudian sloop rig. Deck stepped timber mast and spars, professionally re-varnished 2019.

Separate fore hatch.

Samson post on fore deck.

Hyde Heritage cream sails: new furling genoa and new mainsail (2020).

During the restoration new mild steel floors and keel bolts were fitted. New mild steel tabernacle, bespoke bronze chain-plates and bronze bumpkin, restored bronze winches. The interior was completely stripped and refurbished, new flexi-teak laid decks, refurbished original cockpit.

Nasa depth sounder, Plastimo compass, wooden boat hook, whisker pole, warp, fenders and additional safety equipment.

VHF radio.

ST 2000 Raymarine auto tiller.

Matching covers for mainsail, cockpit, coachroof, fire hatch, winches. Heavy-duty winter cover.


Over the years we have sold many ‘Z’ Four-Tonners and CONSTAR, following her professional Fairlie restoration is probably the best example of her type we have seen. Great attention to detail and period style was paramount during her re-build, making CONSTAR a very usable and desirable yacht indeed in excellent condition all round.


LYING: Chichester Harbour


DISCLAIMER: Classic Yacht Brokerage offer the details and photographs of this vessel in good faith as a guide but cannot guarantee the accuracy of this information or images, or warrant the condition of the vessel, machinery or rig. Buyers should instruct their representative, agents or their surveyors to investigate such details as the buyer requires validated. This vessel is offered subject to prior sale, price change, or withdrawal without notice