There's not a lot to report on K7 at the moment. The RM is rapidly learning that the canopy is difficult, there's still no spray baffles, the paintwork is suffering through endless backpacks, zips and handbags being dragged over it and their engine is as dead as it was last time we looked, but other than that - no progress, so as my last scribblings on underwater exploration were well received I thought I'd do another.
I need to be wary of stealing my own thunder here, though as there'll be nothing left for those books I keep promising to write but this was an interesting little adventure. It's only a few paragraphs for now so enjoy and if you do enjoy please let me know and I'll add some of the other wrecks we shot on this trip.
So here goes.
Back in whenever I was contacted by a bloke called Crispin Sadler about making a series of documentaries. These days you'll find Malinson Sadler Productions draining the oceans left right and centre and this was an early foray down that route with a slightly different format. It was called Deep Wreck Mysteries and the plan was to both image and dive shipwrecks then tell their story as a sort of docudrama. We'd image the wreck with sidescan then send divers down for a look then interpret the wreck with both acoustic imagery and underwater footage.
The wrecks were in the Bristol Channel so our base was Padstow with local skipper Chris Lowe and his boat, Atlantic Diver.
Chris is a superb skipper and could handle his boat to within an atom so once we'd festooned it with sonar equipment and turned his wheelhouse into mission control we explained the whole straight line, constant speed thing and off we went to image shipwrecks. It soon became entertainingly competitive. We'd shoot an image and say, that's not bad, a little too far to the left, or whatever, and Chris would immediately line up his boat for another go to beat his last line. It gave excellent results.
Chris, on the right in his captain's chair. The chap in the middle is Phil Durbin, an accomplished diver who often dived off Chris's boat. He was intrigued with the whole sidescan thing. Phil was tragically lost in a diving accident some years later.
When we went aboard we were promised that lunch would consist of the finest Cornish pasties - and it did and they were delicious.
And so were the ones we had for lunch the next day, and the day after, and the day after that. I was a bit fed up with Cornish pasties for months later. Another peculiarity of Padstow was that everyone seemed to be murdering sharks as fast as they could. I assume this has been reined in these days.
But back to the sonar. We rented a sidescan for this trip, a 410kHz Geoacoustics system with a Coda top end and Coda Geosurvey post-processing software. I really liked that setup. 410kHz gives good resolution with good range and in my view is an excellent compromise for imaging wrecks. We also had a 375kHz setup but it couldn't significantly improve on the image whilst losing out a little on the range.
Our first target was a Canadian corvette called Regina. She's in about 60m of water and her story goes like this.
On the 8th August 1944 the tiny corvette was escorting a convoy to Normandy when one of the ships, a liberty ship called Ezra Weston was torpedoed. Ezra Weston was carrying miles of Bailey Bridge sections and was badly damaged. The captain of Regina, wrongly assuming the ship had hit a mine, slowed to help and was almost immediately torpedoed too. There was a huge explosion and the gallant little ship sank from under the sailors' feet taking 30 crewmen with her. As she went, one of the sailors aboard realised there was a lot of armed depth charges on deck and that if they detonated - as they would - when the ship sank, men in the water were far from safe so he frantically disarmed them. The Ezra Weston was also fatally injured when Regina blew up and went to the bottom too.
Regina had been dived extensively and the divers reported the stern blown off and the truncated wreck ending at the sheared ends of the propeller shafts. It was our job to get a much broader overview of the site to see if we could turn up any new information and were they in for a surprise!
What no one knew was that although the stern had been blown off, it wasn't just the very end shattered to a million bits as had always been assumed - the ship had been cut in two by the torpedo with the undiscovered and un-dived stern section lying close by. No one had expected that.
The line down the centre is where the sonar can't see, remember? you can also see that it gets narrower towards the top of the image indicating that the seabed is rising or the boat is slowing. Either way, the fish is getting closer to seabed. The forward part of the wreck is on the left, note the shadows it casts indicating that it's standing quite tall above seabed. The point of the bow is pointing up the page. The severed stern, on the other hand, is more flat and broken indicating that it sank rapidly with air still trapped inside. This causes the sinking ship to crush and break.
It took many attempts to get this shot because if you look top right you'll see wavy lines and that's fresh water rolling along the bottom, it was a real nuisance on that site. Sometimes we'd get a clean shot of the bow but the stern would be covered and vice-versa. This time they were both in the clear and this became the money shot.
The Regina story was (I think) episode 2 and it will be available to view somewhere so for the full story go dig it out.
Bill
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