Sheephaven SAC update and “Operation Deadlight”

Feb 12 2015 Posted by Office Administraton

8th February 2015. It was a beautiful morning for a boat dive on Saturday morning with clear skies and practically no wind. You could hear the surf still pounding out to sea so they stayed in Mulroy Bay and dived the First Narrows at Slack High Water. Maximum depth achieved was 24 meters, while a surface to surface time of greater than 40 minutes was reported by the divers. Air temperature and in-water temperatures were the same, both at 6 degrees Celsius, which were so much more comfortable than other dives recently. While they didn’t see any Otters in the water on Saturday morning there was clear evidence of their presence at Mevagh slipway, with the remains of a crab dinner and some other signs.

They had a perfect morning’s snorkelling out from PortnaBlagh on Sunday morning, with clear sunny skies, no wind and a gentle swell. There was a big turnout of club members to take full advantage of the excellent conditions, where water temperatures were 6 degrees Celsius, while air temperature initially was no more than 3 degrees Celsius.

For a number of the snorkelers it was an opportunity to complete their obligatory water fitness test in preparation for their dive season, for which they require three diving consents or green lights on COMS, one of these green lights is the water fitness test.

A great morning to be in the water and hopefully bodes well for club activities as we head towards the spring.

Sheep3 Sheep1 Sheep2

Wednesday 11th February saw the 69th anniversary of one of the last acts of WW II, when captured German U-Boats where scuttled off the coast of Co. Donegal as part of Operation Deadlight in 1946.

After German capitulation 156 German U-Boats surrendered in various parts of the world, but the vast majority ended up in Lisnahally docks on the River Foyle and from 17th November 1945 116 were taken out and sunk at different locations.

Most of the surrendered U-Boats were made up of Type VII, which went through a number of variations until they were ultimately superseded by the vastly superior Type XXI by the end of the war. The original Type VII variant had a displacement of 626 tonnes, was 64  meters overall and was propelled by twin MAN 6 cylinder 4 stroke diesel engines giving up to 2,300 HP and two electric motors giving 750 HP.

Maximum speed on the surface was 17 knots, submerged it was 8 knots, while it had a maximum range of up to 6,000 nautical miles. There were over 700 Type VII’s brought into active service throughout WW II.

In contrast the Type XXI displaced over 1,600 tonnes, was 76 meters long and was propelled by 2 supercharged 6 cylinder MAN diesel engines, generating 4,000 HP, 2 electric engines producing 226 HP and had a range of up to 15,500 nautical miles.

Apart from the difference in size the big difference between the Type VII and Type XXI’s was the Type XXI’s speed and endurance; its surface speed was 15 Knots, however while submerged it had a speed of 17 knots compared to the Type VII’s 8 knots. The Type XXI could stay submerged for up to 340 nautical miles or up to 3 days at 5 knots, compared to 80 nautical miles for the Type VII, making for a vastly superior tactical submarine.

The Type XXI U-Boats came late in WW II and only 4 were launched from 118 that had been completed using a revolutionary prefabricated construction technique, these electric boats would have had a profound effect if they had got loose in the Atlantic had the war continued much longer.

Both of these boats have a Donegal connection, with Type XXI Deadlight boats U 2511 and U2506 discovered off the Donegal coast between 2001 and 2003 and when dived on by technical divers were found to be in good condition. While there are a number of Type VII’s sunk of the coast both as part of Operation Deadlight and as a result of combat, all are currently beyond the reach of recreational divers.

However lying off Malin Head is U 861, a Type IX U- Boat that was also part of the Operation Deadlight and was sunk on the 31st December 1945. The Type IX’s were big boats at 87 meters long and had a displacement of 1800 tons, of which only 30 were built. U 861 had 2 MAN Diesel engines along with twin auxiliary diesels producing 5,400 HP and two electric engines producing 1,100 HP, giving a surface sped of 19 knots.

U 861 now lies in 43 meters at a location between Malin Head and Inishtrahull Island and has been dived on a number of times by Sheephaven divers. She lies on her port side, with the hull split open and one of her diesel engines lying on the seabed some distance from the wreck. The hull lies astride rocks, which allows the diver to briefly get under U 861 and then proceed along the wreck for as long as bottom time allows.

U 861 is at the extreme range for recreational no-decompression diving and in addition to the depth has issues with a severe tidal current that calls for the greatest caution when attempting this dive. However U 861 is one of the few WWII U boats that can be dived in Irish waters by recreational divers and is well worth the effort if the opportunity arises.