Monday, April 11, 2011

M-Class Minesweeper M483

The M 483 Minesweeper (Minensuchboot) was built in the 1940s by N.V. Boele's Scheepswerfen & Maschinefabriek shipyard located in Bolnes, The Netherlands as a minesweeper or escort vessel for the Kriegsmarine.

Construction was transverse frame of steel construction, which was partly welded, this vessel also had eleven watertight compartments and a double bottom with hard chine foreship and tug stern. The superstructure, Bridge etc was armored up to 10 mm in thickness. The propulsion system installed in these vessels was the two vertical three cylinder triple expansion engines. And when used as minesweepers the Kabel Fern Raum Gerat (KFRG) system was employed, which used generators producing 60 V, 20 kW to power the magnetic sweeping gear.

This vessel went on to serve in the 24. Minensuchflottille during World War II.

1 December 1942
The Minesweeper M 483 is commissioned.

The Minesweeper M 483 becomes operational with the 24. Minensuchflottille.

15 June 1943
The Minesweeper M 483 is sunk after being attacked by Allied aircraft at 0614 hrs, near the Channel islands.

On June 15th 1943 263 squadron with the support of 8 spitfires from 616 squadron and 8 spitfires from 504 squadron undertook an early morning roadstead which took them to a few miles NE of Sark. In the ensuing encounter RNZAF pilot R.J. Simm of 616  Squadron was shot down in Spitfire VI BR319 YQ-C, RAAF pilot M.T. Cotton of 263 Squadron in P7000 dropped his 2 x 250 lb bombs and sank the German Minesweeper M483 before being himself shot down.
Draft Surfat report: Lee-White (Red1), Wood (Red 2), Cotton (Blue 1), Ridley (Blue 2), 10/10 cloud at 1500, TOA 0620, 49 28 N, 02 17 W, 4 warships steaming NE at about 8 knots followed by an armed trawler. Ships 1 and 2 were abeam of each other about 60 yds apart, ships 3 and 4 in same formation about 150 yds astern. Ship 5 was perhaps 700 yds astern of the others. Ships 1 and 2 were identified as M class minesweepers, Ships 2 and 4 were two funnel warships very like the escort vessel (Geleiteboote).  All port beam attacks, 8 x 250, GP,11 secs, results not seen because of 11 secs delay. Excellent attacks on ships 1,2,3,4 by 8 Spits of 616 Sqn antiflak. Claims : Ships 1 and 3 claimed Cat 3, our losses: 1 WB Cat E, Max Cotton missing, believed killed.// An armed, escorted shipping recco had been ordered to take off at first light on 15 June 1943 to recce the CI shipping lanes. The 4 WB 263 led by Lee-White t/o Warmwell 0543 and joined up with 8 Spitfires antiflak of 616 and 8 Spits escort cover of 504, over Warmwell below 200 ft. They flew just above sea level with 616 and S/L Lucas leading, then the Whirlibombers in line abreast with 2 sections of 504 in line astern on each side of them. Flying west of Casquets and turning left to the east when 2-3 miles NE of Sark, they saw a convoy of 4 small warships followed by a smaller ship steaming NE about 4 miles NE of Sark. After a series of attacks by 616 Sqn during which the WB saw very good concentrations of cannon-fire entering the warships. The WB bombed ships 1 and 3, 2 M-class minesweepers, in a straight approach at sea level from the port beam. Red 1 and 2 do not see how their bombs could have missed ship 3, but their explosions were not seen owing to the 11 seconds delay-fusing. Blue 1 (Cottons) bomb splashes were seen by Blue 2 (Ridley) amidships on the waterline of ship 1. Blue 2 made a similar attack on ship 1. Flak from the warships was very intense, and accurate. A Spitfire of 616 was set on fire by it and the cockpit of PO Cottons a/c exploded in flames just over the top of ship 1, probably hit by a 40 mm shell from ship 2 which was (as was ship 4) a 2-funneled ship like a small destroyer, probably a Geleitboot. Cottons aircraft disintegrated as it hit the sea. It is not thought possible that he could have survived. Blue 2 a/c received a glancing hit on the fin (Cat B). WBs then reformed with their escort and RTB, where they landed 0650. The WB following the memorandum of S/L Warnes did not use cannon, but Blue 1 used CCG.

Shot going in
Wreck showing on sounder
Dive team....
Dave... Boat man

Bottom Time 20 minutes.
Depth 52 Metres
Visibility 5/6 Metres
Bottom Gas 20/30 Tri mix
Deco 50% Nitrox 

Well, it was another beautiful day to be out. I was worried that the visibility would not be so wonderful due to the recent double Noreasters, but I didn't care, I needed to get out and dive. As we broke out of St Peter Port we headed East to the back of Sark. We were off for our 1 hour ride to the M483. Once we arrived on the wreck the wind and the seas started to pick up but not enough to deter us. My dive buddies for today were Nick and Mike.  As per usual I was geared up and tapping my toe waiting for word that the pool was open.                                                                                                                                                                          Once we were anchored on the wreck, I splashed to find the surface visibility to be only about 3/4 metres which was less than I expected, but once we got to about 40 metres down I could see the wreck come into view. The visibility cleared up to 5/6 metres and it was a little dark due to the start of a plankton bloom starting early with the unseasonal warm weather. The water temp on the bottom was a nice warm 9 degrees and the maximum depth I hit was 49 metres, with the sea bed at 53/54 metres. Mike on Gulf Stream anchored us right on the wheel house or whats left of it after a  2x250 Lbs bomb had hit just forward of where I was, which couldn't be more perfect as you could see right down into the hull of the ship. I quickly got busy foraging around in the carnage of twisted metal and armoured plating. Making my way forward and swimming over the bow a small-calibre anti-aircraft gun still points skywards searching for its target after 60 years of being on the seabed.  Taking a closer look at the breach you can still see the magazine of bullets still loaded.  Moving back towards the shotline we found lots of steel wire cabling, fuse boxes and other artifacts. This must be some sort of generator or electical room which is now largely filled with fallen debris.
 I agree with the repotrs that this is the area of the 483 that had a heavy hit from those 250Lbs bombs, it does appear she was hit hard with a grippling blow.  Nick and I worked our way back to the bow and the ascent line. After almost an hour of dive time we boarded the boat.   The wind was still blowing a  good 4 from the North and we had a sloppy boat ride back to the harbour.

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