Chatham Commercial Dock is located on the lower reaches of the River Medway in Kent. The dock entrance consists of two locks in which the four caissons are located. These are drawn back into the chamber recesses within the central island between the two locks by means of hydraulically operated geared chains. The gates required refurbishment.

Beckett Rankine were appointed to undertake the development of the marine civil aspects of the Chatham Docks Caisson Refurbishment project, which Peel Ports identified as an urgent requirement. Due to deterioration, replacement and strenghtening of existing timber decks was required on all caissons.

Adequate flexibility and strength requirements were assessed taking account of future port operations and the continued need to transit some HGV traffic across the gates. ACME panels were also considered as a potentially durable and lightweight alternative to the more expensive timber solution.