Volume Twelve - Pre-Victorian to the Present Day - further aspects - Report upon Penarth Dock - 1984 . . .

Although the gates at Penarth Dock were equipped with their own sluices these were not sufficient and so most of the sluicing was done through the sluiceways which were built into the walls near the gates. The side walls therefore had to be thick enough to contain the sluiceways and still retain their structural integrity.

The chains used to operate the gates passed through the side walls and up to the hydraulic hauling machinery. They passed through chain paths which were fitted with rollers to allow the chains to pass with reasonable ease. As in the case of the sluiceways the side walls had to be thick enough to contain the chain paths.

The side walls behind the gates had to be thick enough to allow the gates to recess into them so that they did not obstruct the passage of vessels. The gate recesses also had slots in them to contain the various adjustment bars necessary for the adjustment of the rollers and sluices built into each gate.

4.2 -  Lock

The lock at Penarth Dock connected the main dock to the basin. It was a conventional lock with two pairs of gates, one at either end. The width of the lock was 60 feet and the total length of the lock chamber was about 270 feet. During spring tides the total depth of water over the lock cill was 35 feet and this reduced to 25 feet during neap tides. The lock chamber was spanned by a single span hydraulically operated swing-bridge carrying a single track railway and road across the lock chamber.

The floor of the lock had a large extent of invert with the inner cill situated between the invert and the inner gate floor and the outer cill situated between the outer gate floor and the apron. The apron at the outer edge of the lock protruded into the basin whilst that of the inner protruded into the main dock.

Most of the side walls of the lock were almost identical to the solid walls used to construct part of the main dock, whereas, for reasons already explained the walls behind the gates were much thicker. Near the inner end, the side walls had two parallel slots running down them and these probably originally carried water pipes supplying hydraulic power to the lock machinery on the opposite side of the lock from the hydraulic power station.