Overhauls for Forth Ports' Caisson Gate

April 2016

Forth Ports' Caisson Gate “A” docked at Leith dry dock for a nine year overhaul. The gate is one of three and is a vital part of the lock system which Forth Ports use to keep Leith docks non-tidal. The gates measures at 120ft x 23.6ft with greenheart timbers used for sealing the locks. These timbers were all removed and all fixings renewed before the new predrilled timbers were replaced. This is a timely process due to the weight of the timbers and requires the use of either a crane or fork truck.

During the overhaul, the transverse frame and bogey assemblies which enables the gate to manoeuvre on fixed rails, were removed and brought into the workshop to be stripped down. These parts consist of eight large steel wheels, shafts, bushes and thrust washers. At dock, the parts were replaced with new ones supplied by the Port. Dales Marine’s engineers rebuilt all the assemblies and recorded the final sizes before repositioning back onto the gate.

UHP blasting was then carried out internally and externally to the top 6ft of the gate. The full gate was given two coats of Interturf 16, a Bitumastic equivalent to give strong protection, and assistance was provided to WM Nicols to remove and dispose over 100ft of mud and silt.

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