March 25-26 Field Work
Good joy on Saturday. Went to look for two charted lumps below Ragged Point, and found each of them within a few minutes, right about where the chart says they are. I had looked for them with a fishfinder for two years without success. The chart says the southern one is an obstruction and the northern one is a wreck, while AWOIS does not list the southern one and calls the northern one an obstruction. Both of them look like oyster mesas to me: round and amorphous with nothing even vaguely cultural. Also confirmed the U-boat and puzzle pile are still there, and refined my GPS numbers slightly for the high points.
Ted White sent a copy of the NTSB report on the explosion of the tank barge STC 410 at Piney Point on 20 December 1986. It says two 8-ton hunks of the starboard side were tossed 700 feet shoreward by the blast, and "the major portion of the main deck over the No. 5 tanks, port and starboard, had been thrown by the explosion into the deeper (40 feet or more) water on the offshore side of the pier T-wings." The barge was lying on the inshore side of the upriver T-wing at the time. The distance from the puzzle pile to her location is about 320 yards.
With confirmation that the blast was violent enough to throw tons of metal around, and given the torn, heavy plates of the puzzle pile and the piece of heavy Nylon line wedged into the peak of the pile, I'm fairly confident that the pile is a piece of the barge. Next item on the agenda is to compare the official dimensions of the STC 410 (at least her beam) with the inverted barge (53DTON_2 = SHIP 1351) lying in 70 feet at the St. Mary's River mouth to see if that is as far as the salvage effort got. The stern was pretty well vaporized by the blast, so we might not find the stern towing notch. Her overlall length was 300 feet. The aft section, perhaps 75 feet, was blown off, at least above the waterline. If the St. Mary's barge measures 60 by 300 - 75 = 225 feet, or 60 x 300 with one end mangled, I would say we have a winner -- and a bad case of littering.
The advantage of the sidescan over a fishfinder is enormous. In 60 feet of water the fishfinder's 12-degree signal cone covers 124 square feet, while the sidescan covers about 360 square yards or 3,240 square feet -- 26 times as much -- with better resolution. It's like looking through binoculars after trying to use a toy telescope. The resolution is good at speeds up to 4 or 4.5 knots. We can also determine the length, breadth, depth, and orientation of a wreck whilst lounging on the lido deck with a mai tai. Anyone want to buy some old, beat-up dive gear?
Sunday's small craft advisories were overstated, so Joe Keefe and I went out but did not go far from home -- just played in the river, looked briefly and unsuccessfully for the R. B. SPEEDEN (a lumber schooner that sank in 1929 near Tall Timbers), and learned how to mark targets and save images as bitmaps. Next step, link the sonar to the laptop to display everything with a larger screen and to store it in a bigger memory.
More sidescan on 1-2 April, at Point Lookout if we have divers, around St.George Island if not. Kurt, if you want, we can put the sidescan on the skiff and take pics of your field school wreck -- but the screen scrolling speed is not pegged to boat speed so the images are not scaled.
U-buoy 8-9 April, or 15-16 April if we get blown out on 8-9.