Off Gassing March 2010

	Issue 24 March 2010
	Off-Gassing...
	(Web Version)

Has anybody got any novel (and legal) ideas for the charity fund raising this year The last couple of years have been very successful with the 24 hour dives at Dosthill, but the committee wondered if you would like to do something different to raise the profile of the event further. Please let one of the committee members know.
BSAC Fees Remember BSAC fees are due if you want to dive, get insured!	Have you got any ideas about what trips you would like to go on? What about courses that you would like to take part in? Let any of the committee members know about your ideas Editor’s Corner Thank you to everyone for their contributions and comments and if you have anything that you would like add to the newsletter, let us know by 20th April so it can be included in the next issue.

Excuses for not doing a night dive

It’s dark.

The dog ate my torch.

I dropped my torch in the pond when I was checking to see if the fish were still alive and I am going to have to drain the pond out in order to find it.

I ran over my torch when I accidently left it under the back wheel.

I’ve got a puncture.

I lent my torch to my cousin, who dropped it down the drain he was inspecting.

I’ve got to visit my cousin in hospital (he fell down the drain trying to get my torch back).

It’s cold.

I’ve got a cold coming.

I’m just getting over a cold.

You’ve got a cold and I don’t want to catch it.

You don’t sound very well – let’s go for a drink.

Isn’t it illegal to dive after dark?

My hair needs washing.

It makes my hair smell.

It’s too late to wash my hair by the time I get back from the pub.

I have to go to the pub earlier because otherwise it is too late to wash my hair by the time I get back home.

Wreck of the Month - HMS Umpire

Type : "U" Class Submarine                                       Cause : Collision/Rammed
Skipper : Lt Mervyn Wingfield                                   Location : Off Wells Norfolk.
Displacement: 730 Tons                                              Length: 58.10 metres
Complement: 33 Officers & men                                Armament : 4 - 21" torpedoes
Surface Speed : 11.5 Knots                                         Submerged speed : 9 knots
Power : 825 HP                                                           Position : 53-00'N 01-00'E

The U class was developed as small and manoeuvrable coastal submarines for use in the waters around the UK with a displacement of some 730 tons and were designed to replace the First War H class boats. The U class was a "single hull" design with water ballast and fuel tanks located within

the pressure hull and with no external saddle tanks. HMS Umpire was laid down in 1939, initially as the P31, and was built at HM Dockyard Chatham, Kent. The boat was finally launched on the 30th December 1940 and commissioned on the 10th July 1941.

Armaments consisted of four 21" torpedo tubes with a cache of eight Whitehead torpedoes together with a three inch deck gun which could fire a 17.5 lb shell to a range of 12,000 yds.
The boat was on a work up patrol and left Chatham on the 18th July 1941 and stopped overnight at Sheerness on the Isle of Sheppey to wait for assembly of a north-bound merchant convoy leaving the Thames and gathering off Southend. The boat then set out for Dunoon Scotland and the Clyde to join the 3rd Submarine Flotilla and was under way on the surface following the northbound merchant convoy EC4 in a swept corridor around the East Anglia and then towards Scotland.

A Heinkel attacked the convoy and Umpire crash dived to avoid it ( as per standing orders) but on surfacing, one of the diesels developed a fault on the night of the 19th July and had to be shut down. This reduced Umpire's speed and a radio message was sent to the Commodore of the convoy, reporting this. A Motor Launch was sent back as escort but lost Umpire in the gathering darkness.
A second merchant convoy was expected travelling south, also in the swept channel and both convoys passed starboard to starboard, which was unusual. Umpire spotted the southbound convoy and altered course to port to avoid a collision, but was rammed by a Royal Naval armed trawler "Peter Hendriks". Umpire suffered damage to the starboard side and sank within 30 seconds in about 60 feet of water. The skipper and the OOW Tony Godden were on the bridge with two lookouts when the submarine sank beneath them, leaving all four in the water.

The remainder of the crew and two officers were trapped in the hull which was gradually filling with water. Four made an escape from the conning tower without DSEA They made a good exit and all four reached the surface, but two had held their breath and, though picked up, died later from ruptured lungs.
Due to the list, the bulkhead door of the engine-room would not close properly and the compartment was slowly but steadily flooding. Twenty men had taken refuge here and prepared to escape using the Davis escape trunk. Only 17 had Davis escape gear, so three of those went first, with the three without escape lungs clinging to their legs. Two of the latter didn't make it to the surface, as they were knocked unconscious after hitting gear outside the escape hatch, and let go.
A seaman called Killan then took charge of those left in the engine-room. First he ducked under water into the trunking, went up it to make sure it was all clear, and finally returned to the engine-room. Then he sent the others up one by one. He was the last to leave and was rightly awarded the British Empire Medal for his bravery.

A total of two officers and twenty men were lost, the wreck is classified as a war grave and lies some 20 nautical miles north of Wells-next-the-sea Norfolk.
The submarine lies on its starboard side, so the upper surface here is the port side. Looking forward, the keel is to the left and the deck to the right.
This shallow, there is plenty of natural light, which serves to enhance visibility. The hull is coated in a dense carpet of hydroids, with clumps of big plumose anemones on exposed ribs.
Heading forward, the hull is soon broken and collapsed where the main control room would have been beneath the conning tower. The wreck then gains more structure, with the lower part of the hull pretty solid, though the upper part is broken clear.
Stacks of batteries can be seen through gaps in the internal deck, where rectangular plates have fallen clear.
Fourteen of the 31 crew were lost when HMS Umpire was accidentally rammed by the Admiralty trawler Peter Hendriks, so this submarine should be treated as a war grave, with a look-but-do-not-disturb approach to diving.

To the forward end of the control room, an intact bulkhead separates it from the torpedo-room. The hatch that was closed so heroically when the torpedo-room flooded now lies open.
Staying outside the hull, a section of bent pipe lies propped against the deck from the seabed, with cables draped over it. All are covered in anemones.
The first feature of the bow deck is the torpedo-loading hatch, a sloped tube angled forward into the deck, through which torpedoes would be slid into the torpedo-room.
The hatch-cover is open and hanging below, hinged to the starboard side of the wreck. Looking in, a green glow from the break further forward can be seen through the torpedo-room.
Next along the deck comes the forward escape hatch, again open. The Peter Hendriks struck HMS Umpire near the bow, flooding the forward torpedo-room. While others escaped through the aft escape hatch, no one survived from the forward part of the wreck, so this hatch was most likely opened during subsequent salvage.
The last item on this intact section of bow deck is a small anchor winch. This would normally have been enclosed by the outer hull, but the bow forward of here is just debris. Forward of the anchor winch, the wreck is cleanly broken pretty much completely across.
Looking back inside the torpedo-room, what looks like a re-load torpedo rests on the lower side of the wreck.
Further forward, the wreck is flat to the seabed, just a few curved plates rising above the sand, some with flanges and valves projecting. It's hard to tell just how much of this damage was done by the original collision and how much by subsequent salvage to recover the four torpedo tubes for their non-ferrous metal.
A fair amount of wreckage has fallen away from the deck, so on the swim aft it is worth looping out a little, keeping the main body of the wreck in sight.
One of the bow hydroplanes stands upright in the sand, just about level with the anchor winch.
In addition to torpedo tubes, HMS Umpire was armed with a 12-pounder gun, a 3in gun and 3 x 0.303in machine guns.
Just out from amidships, the mount for the forward 12-pounder gun lies on one side with a section of hull-plate resting over the top of it. The gun itself is missing, presumably salvaged, or perhaps it is buried somewhere nearby. There are certainly no signs of it under the plate.
Close to the base of the gun-mount, but still detached from the main body of wreckage, a curved section of metal partly buried in sand and gravel is the remains of the conning tower.
The 3in gun can be found further aft, lying on one side half-submerged in the seabed and again separated from the main body of the wreck.
At the stern, the rudder is an open framework angled slightly to port (up) and the diving plane angled slightly down. The port propeller-shaft projects on the upper side of the wreck, the prop itself being another item which would have been salvaged. The starboard shaft is buried.
The tail section of the wreck is broken from the rest of the wreck where the engine-room has been broken open.
The main objective of the salvors here would have been the copper from the electric motors, and the remains of what looks like the armature of an electric motor lies cleaned of its windings among the debris. It is from the engine-room escape hatch that the surviving crew swam to the surface.
The members of the commercial salvage team certainly knew what they were doing. The wreck has been opened out completely, right where the main objects of salvage could be found: the electric motors, the control-room instruments and periscopes, and the torpedo tubes at the bow.

Creature of the Month - Yellowmargin Triggerfish

Family Balistidae
Distribution: Atlantic, Indian and Pacific Oceans. Usually compressed body. Pelvic fins fused to one spine. First dorsal spine with locking mechanism . With 12 principal rays in caudal fin. 18 vertebrae . Upper jaw non-protrusible. Upper jaw usually with four teeth in outer and three in the inner series on each premaxillary . Capable of rotating eyeballs independently. Triggerfish normally swim by undulating their second dorsal and anal fins, but will use their tail for rapid bursts. Most triggerfishes are solitary diurnal carnivores, feeding on a wide variety of invertebrates including hard-shelled mollusks and echinoderms; some also feed on algae or zooplankton . They lay demersal eggs in a nest which is aggressively guarded by the female, less often by the male. Popular and hardy in aquaria, but often aggressive.
The family Balistidae belongs to the Class Actinopterygii (ray-finned fishes ) and the Order Tetraodontiformes. It contains 11 genera and 40 species. It may be found in Marine environments and is primarily Marine. Many members of this family are used in the aquarium trade. Reproductively, most members of this family are guarders. Nest-guarding females are aggressive. Head butting seems to be a favourite trait for some, as those of us having encountered them have found out. It can certainly be quite discerning to have a very persistent trigger fish following you on your dive, and a great photo opportunity for your buddy, once they have stopped laughing.
The main mode of swimming of adult fish in this family is balistiform. This is simultaneous undulations of the dorsal and anal fins. Named after the Balistidae family (Triggerfishes) that typifies this classification. While Balistiform locomotion is the primary swimming mode in triggerfishes, it is almost never seen in other fish families, not even for intermittent swimming. Balistiform locomotion may have evolved along with the "trigger" mechanism in the triggerfishes. The trigger mechanism may require strong musculature, which in turn could be used for fin movement. This however, would not explain the usage of the anal fin, as the trigger musculature is located along the dorsal axis.
Compared with other fish, the activity level of this family tends to be normal. Members of this family have been dated back to the middle Oligocene epoch of the Tertiary period(about 34 million years ago). Etymology of this family name : Greek, balein = to throw
Habitat
Found on lagoon slope and floor, also coral reefs. Also caught with drive-in nets . Marketed fresh and dried-salted. Typically found in water with a depth of 0 to -5,214 meters (0 to -17,106 feet).
Biome: Saltwater . Reef-associated .
Diet
Feeds on tips of coral branches, gastropods , crustaceans, foraminiferans, and tunicates and also on sea urchins. Ciguatoxic in certain areas.

Thanks to the Editor: Phillipa Cresswell,