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

	Figure 17 - Section through lock chamber showing wall bordering invert.
	Figure 18 - Section through wall behind gate recess.

4.3 - Sea Entrance

The sea channel at Penarth Dock connected the half-tide basin to the Bristol Channel. [correction : The Severn Sea - traditionally the Bristol Channel commenced in a line westward of Lavernock Point and across channel to Brean!]. It had similar dimensions to the lock, namely a width of 60 feet and a depth of water over the entrance cill of 35 feet during spring tides and 25 feet at neap tides.

The sea entrance had two pairs of gates although they were not arranged to form a lock chamber. Instead the inner gates were used to maintain the level of water within the basin whilst the outer pair were used to protect the inner gates from the effects of high tides and heavy seas.

Due to the close space of the gates the invert was practically non-existent and the cills were built adjacent to one another.