This rather nice but often overlooked bucket dredger is usually teeming with fish, writhing shoals of huge pouting inside the wreck and some big pollack above.
A dive on the St Dunstan usually begins at the bow, the only part of the wreck sticking up far enough to easily lay a shot. Hull plates have fallen away along both sides of the up-turned hull, with the better access to the interior being on the starboard side. A large pile of debris just inside the wreck is mostly the anchor chain, with some scraps of other wreckage and the anchor winch buried underneath.
Immediately behind this pile of chain is something that came as a total surprise to me the first time I dived the St Dunstan, but was pretty obvious once I considered the engineering of a bucket dredger. There is a pair of enormous boilers right at the front of the wreck. It is probably these boilers that are holding the rest of the wreck up above them. The boilers and engines are at the front of the ship to make room for the dredging machinery further aft.
Leaving the engine room machinery alone for a while, just off the starboard side of the wreck are a set of enormous gears, part of the drive machinery for the dredge system. One of these is still attached to the top of the chain of dredge buckets.
Easily one of the more robustly built parts of the St Dunstan, the arm and bucket assembly has fallen clear of the hull and is pretty much intact, lying on one side and leading towards the stern. There is a slight bend near the top of the arm, then about halfway along it is partly covered by a hull plate.
A few buckets before the end of the arm and just out from it, a large pulley block is part of the mechanism used to raise and lower it.
Just off the end of the arm is an upside down scoop, several times the size of the individual dredge buckets. This would have been the business end of the dredging mechanism.
The rounded stern of the wreck is only a few metres away lying on its port side. The interior has collapsed leaving just the shell of the stern to swim through where it has broken clear of the twin keels.
“Below” the stern a single rudder lies resting flat on the seabed, guarding the two keels and propellers. The port keel is completely inverted, and the starboard keel has collapsed towards it. The hull of the St Dunstan would have had a well in the middle for the dredge arm to be lowered, with one keel running either side of the well.
This begs the question of whether there was just a single rudder, or whether there is a second rudder buried somewhere underneath?
Heading back towards the bow, the starboard keel is broken open, making it possible to follow the propeller shaft forward.
The final part of the dredging mechanism is a large winch drum used to raise and lower the dredging arm. This is still tightly packed with cable and on one end there are another pair of big gears which would have driven the winch from one of the main engines.
The propeller shaft continues forward along the broken open keel and back inside the wreck, ending in the engine room with a bevel gear.
Whereas most steam driven ships would have had no gearbox, with the engine driving directly onto the propeller shaft, on the St Dunstan the main engines would have also been used to power the dredging mechanism, hence the need for elaborate gear systems.