Proceedings Of The Marine

FAL 2012

Proceedings magazine is a communication tool for the Coast Guard's Marine Safety & Security Council. Each quarterly magazine focuses on a specific theme of interest to the marine industry.

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three minutes and 29 seconds. Starting at 1:09:40 a.m., this auxiliary motor increases by 41 rpm until its acoustics are lost simultaneously with ATE 2 at 1:12:31 a.m. ATE 1 Analysis of ATE 1 found that the event was made up of a series of individual sounds. The first sound in this series had the aural characteristics of a metal-on-metal impact. At least 12 short pulses follow this sound in groups of three at regular interval of 9.60 pulses per second, which matches the rotational rate of the tugboat's propeller. ATE 1 could not be definitively explained, but it is most likely propeller cavitation or an object striking the tugboat's propeller. Cornell University's analysis placed ATE 1's location at 42° 25' 1.2" N by 70° 31' 1.9" W, approximately 0.3 nautical miles from the tug's AIS position at 12:07 a.m. The tug's and F/V Patriot's engines remain at a constant speed throughout this event; this provided evidence that a collision between the tugboat and the F/V Patriot did not occur. ATE 2 Navy analysis of ATE 2 describes this event as a metallic thud, lasting less than one second, originating from the fishing vessel. No other vessels were in the immediate vicinity at this time. Cornell analysis placed ATE 2's location at 42° 25' 20.6" N by 70° 28' 16.0" W, approximately one nautical mile northwest of the vessel's wreck location. Immediately after ATE 2, Navy analysts detected a noise with an irregularly increasing frequency throughout the event, consistent with a void filling up with water. This is heard from 1:12:34 a.m. to 1:15:39 a.m. and ATE 3 occurs approximately 6 minutes after this sound ends. ATE 3 Analysts described ATE 3 a series of seven irregular, quiet sounds lasting two seconds total with the final and loudest sound having a hollow metallic quality. Because ATE 3 is only heard on buoy 4, Cornell location analysis was not possible. No further sounds associated with the F/V Patriot are heard after this point; ATE 3 is most likely the sound of the vessel hitting the ocean floor. F/V Patriot engine rpm vs. time, with a red line cor- responding to each aural transient event. Notes: On this chart, an rpm reading of 0 means engine noises quieted to an undetectable level, not necessarily that the engine was shut down; DQDO\VLV KDV D RQH WR ¿YH nautical mile error radius. Chart courtesy of U.S. Navy CUS. About the author: /7 &KULVWLQD 6XOOLYDQ LV WKH FKLHI RI WKH ,QYHVWLJDWLRQV 'LYLVLRQ RI Sector Boston, and was a marine casualty investigator on this case. Her previous assignments include tours at Sector St. Petersburg as a vessel inspector, and at U.S. Coast Guard headquarters in the Environmental Standards Division. LT Sullivan holds a B.A. in communication, specializing in public relations at George Mason University. Endnote: 9HVVHO PRQLWRULQJ V\VWHPV DUH XVHG LQ FRPPHUFLDO ÀVKLQJ WR DOORZ HQYL- URQPHQWDO DQG ÀVKHULHV UHJXODWRU\ RUJDQL]DWLRQV WR PRQLWRU WKH SRVLWLRQ WLPH DW D SRVLWLRQ DQG FRXUVH DQG VSHHG RI ÀVKLQJ YHVVHOV 12$$ DOORZV WKH &RDVW *XDUG WR XWLOL]H 906 GDWD LQ VHDUFK DQG UHVFXH PLVVLRQV 7KH WUDZO GRRUV DUH GHVLJQHG WR ÁRZ WKURXJK WKH ZDWHU DW DQ DQJOH FDXV- LQJ WKHP WR VSUHDG DZD\ IURP HDFK RWKHU RSHQLQJ WKH QHW KRUL]RQWDOO\ 7KH WUDZO GRRUV DUH DWWDFKHG WR WKH ERDW E\ WUDZO ZDUSV FDEOHV 'XULQJ KDXO EDFN RSHUDWLRQV WKH WUDZO GRRUV ZHUH FOLSSHG WR WKH JDOORZV IUDPH LQ SUHSDUDWLRQ IRU WKH QH[W SD\ RXW RI ÀVKLQJ JHDU Fall 2012 Proceedings 11

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