The 9,600-ton Port Napier was loading a cargo of mines at the Kyle of Lochalsh on 27 November 1940 when a fire broke out on board. With such a hazardous and explosive cargo the ship was towed clear of the dock and abandoned just over a mile away. Shortly afterward an explosion amidships blew off part of the superstructure and sank the ship.
Although the basic layout of the Port Napier follows that of a more conventional freighter, the conversion for mine laying connected the holds by internal narrow gauge railway lines on either side of the ship.
Each mine comprised two main parts - the classic spherical mine with horns, and a combined anchor and cable assembly. The anchor was fitted with wheels to make a trolley that could be run along the railway inside the ship.
Mines were stored in sidings beneath decked over holds. To lay a mine the complete assembly would be pushed along the railway and out through hatches located just above the waterline on either side of the stern of the ship. The trolley would sink to anchor the mine to the seabed, the cable would unwind and the mine would 'float' at the set depth.
With the port side of the wreck standing clear of the water, it is easy to begin a dive on the Port Napier right at the bow. Below the bow cables hang and stretch back to the keel. It is hard to tell what their purpose was, but nowadays they are host to some very long and very delicate plumose anemones.
At the bows a pair of 4-inch guns dominates the deck. The starboard gun is at a depth of 11 or 12 metres and slightly forward of the kelp covered port gun. The original wooden decking is still reasonably intact.
Open doorways and windows allow easy access inside the superstructure. Considering the magnitude of the explosion that sank the Port Napier, the area of the wheelhouse is surprisingly intact, but just behind it the structures that would have been above the engine room are a tangled mess. All that is recognisable is the remains of the funnel collapsed forward and resting on the seabed.
Continuing aft, the number 4 hold is decked over. Littered on the seabed is a pile of mine anchors, easily recognisable as over sized "porta-potti" toilets on wheels.
The number 5 and 6 holds are also decked over. From a photographer's point of view, cables dangling from the top of the aft mast to the seabed caught my eye, again covered in long and delicate plumose anemones.
Below the stern railing are the mine laying hatches. The railway lines can be followed forward through junctions and sidings past trains of mine anchors. Every so far shafts of light spray down through holes cut in the hull of the ship. From the number 3 hold a short passageway and a bowed bulkhead allow exit into the open number 2 hold in front of the superstructure.
The Port Napier is not one of Scotland's most dived wrecks, but everyone I know who has dived it reckons it should be. It is a dive you will never forget.