Volume Four - An Era of Change, Uncertainty, Depression & War - Some thoughts regarding the apparent reluctance of Pounds to remove the pontoon . . .

It was fairly big! The total deck area was close to one third of an average sized football pitch.

The pontoon was 15 feet (4.6m) wider than the lock gates which were situated 2,100 feet or about two thirds of a kilometer away, out of sight due to the curvature of the dock. Most could be excused for assuming that a vessel already inside a dock would have initially sailed into the dock through the lock gates and equally it would be assumed that it could be sailed or towed out in the same manner. However, the pontoon was made in two lengthwise sections where a “joint was disconnected”, then each section towed through the restriction and then reconnected once inside. I can’t help but hear some forlorn voice say “I forgot to bring my tape measure with me from Portsmouth, Sir”.

Hands-on engineers will relate to the likely condition of any mechanical connections and sealing arrangements after fifty years service. Those which have also been subjected to regular bathing excursions into a salt-water environment require an even greater amount of sweat and blasphemy before they submit. Had Pounds underestimated the amount of work required to remove the connections between the two sections of the pontoon and/or had they underestimated the work necessary to reconnect them and/or make the pontoon sufficiently seaworthy for its trip to Portsmouth >300 nautical miles away around Land’s End?

A single wall hulled ship would be subject to regular inspection, external hull cleaning and painting in a dry dock or on a pontoon. Most ships suffer bilge water; a cocktail of seawater, oil, sewage, chemical and other nasties from cargo etc. This fluid level would be maintained at a predefined level by the bilge pumps to prevent instability of the ship at sea. So, externally and internally there are systems in place to maintain the hull and protect it from corrosion. The insurers and marine inspectors provide control of the seaworthiness or otherwise of a vessel.

In the case of the Penarth pontoon, it was fabricated by riveting ½ inch (12.4 mm) thick plates together. The external decking and superstructure was almost certainly painted when built and periodically throughout its life, but below the waterline there was probably little or no maintenance in that half century. The dock was probably never emptied and since the hull was flat bottomed it would rest in the mud restricting access to the underside even if the dock was emptied.