Divernet

IT WAS ONLY WHEN WRITING THIS months survey of the German minesweeper M483 that I realised that we have now, extravagantly, had three warship Wreck Tours in a row, and all German.
The M483 is a fine representative of a class of small coastal warships built in their hundreds for general work, from minesweeping to escort and submarine-hunting. Back in Wreck Tour 81 (November 2005), we toured the more broken, but shallower, remains of another member of this class, the M343, sunk in 30m between Jersey and St Malo.
The M483 is deeper at 51m to the seabed on a low-water slack, more intact and an altogether more serious dive.
Its located 10 miles east and a little bit north of Sark, and about a quarter of the way towards Cap de la Hague on the French coast.
Our tour begins at the bomb-hole in the port side (1), where one of the 250lb bombs from the attacking Westland Whirlwind fighter-bombers scored a direct hit. When I dived the M483 it took skipper Andy Leaman a couple of attempts to get the shot in, but when
I arrived at the wreck it was nicely in the bomb-hole. Bullseye!
Next to the bomb-hole, the main 105mm gun (2) stands on a pillar in
a recess in the aft deck, the gun pointing out across the port side towards the attacking aircraft. This gun would have originally been operated from main deck level, but such light decking has decayed, so that only the solid gun-mount braced against the keel remains.
Continuing past the gun and diagonally across the wreck, a pair of depth-charges (3) rests against the gunwale on the starboard quarter.
From here we drop over the starboard side to go round the stern and examine the propellers and rudder (4).
The starboard propeller is intact, but the port prop has a broken blade from impact with the seabed. The rudder is hard to port. Beneath the stern the depth is 51m, so you could leave this bit out to save a few metres maximum depth.
Back above the stern at 47m, a ridge across the deck (5) would have been a guide for mine-hunting cables, trawled from the winch (6).
Heading forward again past the main gun (2), look carefully at the bottom of the recess to find a cone-shaped mount (7) from an anti-aircraft gun.
Back on the main deck, another pair of depth charges (8) can be found resting against the starboard gunwale, next to a small mortar or thrower that would have been used to fire them out to the side.
A little forward and in from the edge of the wreck are a pair of toilets, back
to back (9). I cant help but think this is the sort of toilet a DIR diver would appreciate - fitted with a crossover manifold, of course.
Most of the superstructure has decayed to leave a selection of rectangular holes in the deck the length of the ship. The first such pit (10) is the engine-room, where a pair of triple-expansion engines are buried among the debris. Although not visible, these engines were fitted with exhaust turbines to get the last little bit of energy out of the steam.
Continuing forwards generally to the starboard side of the ship, youll see another mortar with a nearby pair of depth charges (11).
Next we come to a mine-hunting fish, or paravane (12). These would be trawled on cables with the fins on the paravane angled so that they would angle well out to the side of the minesweeper.
Any mine anchor cables intersected would then slide down the tow cables to the paravane where, with luck, they would be sheared by cable-cutters fitted to the paravane. The mine would then float to the surface, be spotted by the crew and shot at to explode it.
The holes along the centreline of the ship are the stoke-holds, where two high-pressure water tube boilers are fitted in a tandem arrangement (13, 14). As with the engines, little detail is visible, because the boilers are largely buried in debris from the superstructure.
The ships boats were stowed either side of the stoke-holds. The boats have either drifted off or decayed to nothing, but one of the derricks remains (15).
Located just forward of the mine-hunting fish, this derrick may also have been used to lower the fish over the side and to recover it.
Forward from here, the hull steps up to an extended forecastle. The outline
of where the wheelhouse was once built on the forecastle can be seen on the deck. A pair of gas cylinders (16) would once have been secured against the back of the wheelhouse.
Forward of these, another cone-shaped mounting (17) would once have supported one of the 20mm anti-aircraft guns. An intact and upright gun-mount forward of the wheelhouse still has a single 37mm anti-aircraft gun attached, pointing skywards (18).
Our tour has now reached the usual bow fittings of a warship, with a pair of capstans (19) for hauling the anchors, mooring bollards to either side and an anchor still in place tightly in the port hawse pipe (20), though the starboard anchor is missing.
Now following the port side of the wreck aft, towards the back of the forecastle some hull-plates just below the deck have rotted through to leave ribs exposed (21). Passing the first boiler, a small rectangular section of superstructure still covers the ladder down, built more strongly than the rest of the superstructure to support watertight hatches.
Behind this, a section of deck grating from above one of the boilers now rests flat on the main deck (22).
Aft of the second boiler, a stretch of intact deck is decorated with a few scraps of debris and a circular hatch at the top of a tubular coaming (23).
This is above the generator room, providing electrical power for the ship and also considerably more power when sweeping for magnetic mines.
It was sealed from the rest of the ship with a small watertight hatch above to ensure that seawater could not get mixed up with the generation of electricity.
Off to the side are more depth charges and another mortar for launching them. Then, above the forward corner of the engine-room, a second small rectangular section of superstructure still stands to cover the ladder down (24).
Our tour is completed at the forward side of the bomb-hole next to yet another depth-charge mortar (25).
With a short slack water, even on neap tides, decompression has to be drifting rather than on the shotline.
With a larger group of divers it may still be wise to ascend the shot and re-group at a detachable lazy shot or decompression station to drift as a group.

Thanks to Richard Keen and Andy Leaman.


TOUR GUIDE
GETTING THERE: Condor Ferries from Weymouth, Poole or Portsmouth to Guernsey, 0870 243 5100, www.condorferries.com.
HOW TO FIND IT: The GPS co-ordinates for the M483 are 49 27.03N, 002 15.21W (degrees, minutes and decimals) with bow to the north-east. At low-water slack, the wreck lies in 51m.
TIDES: Tides in this area are enormous. The M483 should be attempted only on a neap tide at low-water slack, 90 minutes before low water at St Peter Port.
DIVING & AIR: Guernsey - Richard Keen, 01481 265335, email: richardkeen@cwgsy.net. Sark - Sark Diving Services, 01481 832565, www.sarkci.com.
ACCOMMODATION: Guernsey - Auberge du Val Hotel, 01481 263862. Visit Guernsey, www.visitguernsey.com. Sark - Sark Diving Services. Sark Tourism, www.sark-tourism.com.
QUALIFICATIONS: The depth makes dives on the M483 suitable only for those divers with extended range air or normoxic trimix qualifications.
LAUNCHING: Slip at St Peter Port in Guernsey.
FURTHER INFORMATION: Admiralty Chart 3654, Guernsey, Herm and Sark. German Warships 1815-1945, Volume 2: U-Boats and Mine Warfare Vessels by Eric Groner.
PROS: A chance to see the mainstay of German coastal forces almost intact.
CONS: Big Channel Island tides limit the opportunities to dive the M483 to low-water neaps.




The
The main 105mm gun at the stern.

Starboard
Starboard propeller.

Winch
Winch for minesweeping gear

anti-aircraft
anti-aircraft gun at the bow

cable
cable drum

depth-charge
depth-charge mortar, which has been used at some point to secure a shot line

Deckhouse
Deckhouse and steps leading down to the engine-room.

Divernet


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ROADSTEAD VICTIM
M483, armed trawler. BUILT 1942, SUNK 1943

THE GERMAN ARMED TRAWLER M483 headed a convoy of four M-class minesweepers through the darkness of the Channel night of 15 June, 1943.
They moved cautiously towards Cherbourg. Once in that port, the little convoy planned to spend the dangerous daylight hours under the shelter of the massive anti-aircraft defences, writes Kendall McDonald.
By the early summer of 1943, German shipping moved in the Channel only under cover of darkness.
To attack these vessels, RAF fighters and fighter-bombers operated at dawn on armed offensive sweeps, codenamed Roadsteads.
This Roadstead began well before full dawn, when 16 Mark VI Spitfires in two sections (eight from 616 Squadron, eight from 504 Squadron) took off through the gloom, and formed up in front and behind four modified Westland Whirlwinds - Whirlibombers.
These twin-engined, low-wing monoplanes had been turned into very fast fighter-bombers, able to carry 250lb bombs or one 500lb bomb in the rack under each wing.
At 6am, the sweep spotted the five German ships through breaks in the cloud four miles north-east of Sark. Finding the convoy was unlikely to have been just luck. The Spitfires and Whirlwinds were obviously following a tip-off, probably sent by a radio operator of a French Resistance group in one of the more northerly French ports.
The Germans were in line ahead, with the heavily armed M483 heading the line. Though she had been built to the basic plans of
a minesweeper of the 1940 class, her layout was heavily adapted by the time she went into service on 1 December, 1942.
Now she was armed like one of the combat boats, with a big 10.5cm Utof gun mounted towards the stern, and had sprouted seven 2cm anti-aircraft guns all over her decks, and one 3.7cm AA gun at her bow.
Depth-charges were lined up on either side of the stern, together with pairs of mortars for launching them in anti-submarine actions.

THE 775-TON WARSHIP, 62m long with a breadth of 8.90m, could do more than 17 knots.
The power came from two vertical triple-expansion engines of 900hp each, with switchable Bauer-Wach exhaust steam turbines of 450hp each to drive two three-bladed screws of 2.15m. She had two rudders and two coal-fired boilers. A crew of 80 was needed to man all her armaments in battles with aircraft, or on anti-submarine operations.
Two minutes after sighting the German ships, the RAF planes were in action. The Spitfires flew in two sections of eight, the aircraft from 616 Squadron to the fore, as they specialised in anti-flak attacks. But all dropped down to attack the ships at just above wave-top height.
Pilot Officer Max Cotton DFC of the RAAF and 263 Squadron picked the M483 as his target and made his Whirlwinds bombing run slightly higher.
Cotton found himself looking almost straight down the barrel of the big 105mm AA gun near the German vessels stern. He released his wing bombs from just below mast height.
At the same moment, according to one of the survivors of M483, Cottons Whirlwind took a direct hit on the cockpit and crashed into the sea, just 100m from the side of his target.
His bombs did not miss. Three Spitfire pilots saw bomb flashes exploding near the stern. They reported that M483 then slewed to a halt and began sinking swiftly, leaving no time to launch her boats.
The four other ships were badly damaged by the Spitfires and the other Whirlwinds, but Flying Officer Robert Sim of the RNZAF of 616 Squadron was killed when his Spitfire was hit by intense and accurate AA fire from the German ships, and crashed on fire into the sea.
He died on his 97th operation in his 588th hour of wartime flying. The battle took less than a quarter of an hour.