WRECKTOUR:166 The Ailsa Craig

I HAD ASSUMED that the Ailsa Craig was named after the island in the Firth of Clyde, but with the ship being built by the Ailsa Shipbuilding Co and operated by Hugh Craig & Co, perhaps that assumption is a coincidence.
With a big granite island famous for quarrying perfect curling stones in mind, I had also imagined this popular wreck to be a bigger steamship. Then, about a week before diving the Ailsa Craig, I thought I had better read up on it, and realised that it was a 601-ton coaster.
I have developed quite a taste for these ships. While hundreds if not thousands of similarly designed coasters were built and, as coasters, many sank in diveable depths, there are always enough differences to keep them interesting, yet enough similarities to make diving them easy.
On a small wreck, skippers typically like to drop a shot on the biggest echo towards the middle, which as usual is the boiler (1).
At 35m to the seabed, most divers will be able to achieve a full circuit of the Ailsa Craig requiring no more than a few minutes of decompression, especially if nitrox is used. Our route forward from the boiler is consequently to the starboard side of the wreck (2), where a hull-plate has fallen across the aft hold.
Between holds is the usual cargo-winch (3), then, as our tour crosses the forward hold, a pair of ribs from the starboard side of the hull remain upright (4).
Inboard from this, a section of the hatch-coaming remains intact (5).
The bow has, unusually, collapsed slightly backwards and to starboard, the opposite direction to most of the rest of the wreck. The small deck-hatch (6) that our route next crosses was actually at the aft of the forecastle, with the pile of chain next to it having slipped back out of the forecastle (7). The anchor-winch (8) is still attached to the remains of the deck, though tilted as described.
Off the starboard side, a reel of mooring cable and a pair of bollards (9) lie on the seabed. Close to the stem, the anchor hawse-pipes (10) are also on the seabed off the starboard side. I suspect that the stem-post (11) may actually rise shallower than the boiler, but just doesn’t show as clearly on an echo-sounder.
Now heading aft again towards the port side of the wreck, the bollards from this side of the bow have fallen much closer in (12) and are followed by another pair of upright hull ribs (13).
As we cross the forward hold, just forward of the cargo-winch is a section of intact wooden deck (14).
Then, aft of the cargo-winch is an Admiralty-pattern anchor (15), a spare that would have been stored secured to the deck by the winch.
These small coasters typically either had a wheelhouse aft, immediately forward of the boiler, or between the forward holds.
The Ailsa Craig’s helm (16) can be found just a little further aft and to port, showing that the wheelhouse was amidships.
Heading back in towards the boiler, some large steam-pipes (17) can be seen on the floor of what would have been the stoke-hold.
Sections of deck-grating (18) lead aft along the port side of the boiler to a solidly standing two-cylinder compound engine (19).
Cutting back across to the starboard side of the wreck, between the engine and the boiler, a small two-cylinder pump (20) can be seen lying flat among the wreckage.
Now following the starboard side of the hull aft and around the stern, a small winch (21) has fallen off the starboard side of the stern.
Beneath the stern, a four-blade iron propeller remains in place, and the rudder (22) is hard to port.
Ascending the stern, the steering quadrant is similarly oriented, showing that the rudder-shaft has not broken.
In the centre of the stern is a solid box-based gun-mount (23), typical of that fitted for defensive armament to many ships in World War 1.
Hydrographic Office reports from 1982 note that the 13-pounder gun was still in place, and boxes of ammunition scattered nearby. Divers must have salvaged these since, because no trace remains.
The deck forward of the stern has collapsed, and a very solid framework from a cabin (24) has fallen angled about 45° from the line of the wreck.
Finally, the top of the compound engine (25) provides a convenient place to pop a delayed SMB and ascend.

Thanks to Douglas Lanfear.

DEPTH -20m 20m-35m 35m-45m 45m+ DIFFICULTY RATING