The Caisson Gate constructed by Modest Infrastructure Pvt. Ltd. will be functioning as the locking gate of the Hughes Dry Dock also known as Indira Dry dock at Mumbai Port Trust operated by the CMSRU (Cochin Shipyard Ltd Mumbai Ship Repair Unit).

Measuring approximately 31.40 metres in length and 13.87 metres in depth from the walkway up to the base-line level of keel and 9.70 metres in width over the timber fendering at the floating level. It floats at 7.5 metres approximately. Caisson is a floating lock gate which can be moved in/ out of position with Tugs. When in a locking position, controlled water ballasting will make it sink into the dry dock seating groove and lock by the hydraulic pressure exerted by water from the outer side of the dock.

The bearing seat surface of the keel and stems is made from the best quality seasoned African Padauk. All the protective wooden fenders are made of seasoned teak wood. The floating dock weighs approximately 1170 Tons (590 Tons steel structure, 250 Tons cast iron ballast and 330 Tons high density concrete).

The controlled sinking operation of the Caisson gate is achieved by inlet valves of scuttle tanks and end water chambers. Inlet of the scuttle tank is closed at 9.455 metres. further sinking is effected only through the water inlets and end water chambers. When the Caisson is fully sunk into the groove the inlets valves are closed. Thereafter water inside the dry dock is pumped out and the dry dock is ready for use.