The first Achilles design was improved by Chris Butler of Butler Mouldings. He added four inches to her freeboard which increased the headroom below and gave the Achilles the distinctive knuckle below her sheer line. This also increased her overall length and she became known as the Achilles 24. The rig was changed from 7/8ths to masthead and the draught slightly increased with the shape of the ballast keel altered to lower the centre of gravity and give the keel a very efficient bulb shape.
Butler Mouldings began to build the Achilles 24 and sail number 17 was exhibited at the 1970 London Boat Show. The class soon gained a good reputation reaching sail number 350 after only four years with the class being exhibited and sold all over Europe. The Achilles 24 was also available as a kit for completion by the owner. An early review concluded that for a small yacht the Achilles was 'hard to fault' and 'exciting to sail'.
Two keel options were available, a single fin or a slightly shallower draft triple fin that allowed the boat to take the ground safely without any other support. The triple keel version retained a 7/8ths rig until about sail number 170 after which a masthead rig was used.
The deck moulding was also redesigned during the Achilles 24 production. The earlier boats had a chain locker but no anchor locker so that the anchor had to be stowed on the foredeck or elsewhere below. This was changed at around sail number 250 when an anchor locker was added. Sometime later, possibly sail number 350 onwards, the cockpit coaming at the main hatch was raised from its original height of two inches and a bridgedeck was made across the companionway at the height of the cockpit seats. For the record my boat, sail number 302, has the anchor locker but retains the low coaming in the cockpit.
There were also detail changes to the design. The cabin widows in the earlier boats were rubber mounted perspex with three separate windows on each side. This was later changed to a single tinted sheet of perspex on each side. At the same time the shroud chainplates were moved inboard to the coachroof from just inside the toerail, allowing a tighter sheeting angle with the headsails. On the foredeck the single cleat was discontinued and twin cleats used, and in the cockpit the locker hinge scuppers were redesigned. There were also changes to the galley during the boats production. By the time production ended some 600 Achilles 24's had been built.