Subject: THRESHER MCP Speed Changes Found in Court of Inquiry Testimony
The paper below will be widely distributed this evening. Bruce, I'm glad we found this as it confirms what you have been saying for many years.
Jim
Testimony Reveals a Slow Variation of Speed of THRESHER’s Main Coolant Pumps Speed (MCPs) Minutes Before Hull Collapse
Captain James B. Bryant, USN (RET.)
On 10 April 1963 at 0918 in the morning the USS THRESHER (SSN 593) was lost 220 miles east of Cape Cod, MA during a routine deep dive test after a nine-month overhaul at Portsmouth Naval Shipyard. It was the first loss of a nuclear submarine and remains the worst based upon the 129 lives lost.
Our THRESHER Volunteer Research Team discovered testimony that likely reveals that the Sound Surveillance System (SOSUS) detected that THRESHER’s Main Coolant Pumps’ (MCPs) speed varied slowly for two minutes before stopping at 0911. After the MCPs stopped, the reactor scrammed causing a loss of main propulsion and THRESHER’s hull collapsed 8 minutes later after plunging to an estimated depth of 2,400 feet. This MCP event was reported first in an April 2013 Navy Times article by Norman Polmar and Bruce Rule. This MCP event is discussed in Rule’s 2018 book Why the USS THRESHER (SSN 593) was Lost, but was reported missing from his testimony.
This slow variation of MCPs between 0909 and 0911 is very likely described in Appendix A and is important because it signals that there was a problem in THRESHER’s Engine Room, probably with varying vacuum in the main condensers resulting in changing Ships Turbine Generator Speed and the frequency of the AC current supplying the MCPs. Just a few seconds after this MCP speed change started at 0909, a 90-second blow of the Main Ballast Tanks was detected by SOSUS indicating the submarine was sinking and could not use main propulsion to surface. The cause of the vacuum change has been suggested to be interruption of seawater cooling flow to the Main Condenser caused by trying to isolate sea water leakage in the Engine Room.
Lieutenant Bruce Rule, USNR was the Sound Surveillance System (SOSUS) Analysis Officer. Rule was tasked to analyzed the THRESHER’s acoustic signature recorded on paper charts by SOSUS, and testify on 18 April 1963 before the THRESHER Naval Court of Inquiry. Appendix A quotes his relevant testimony that was overlooked because key words describing the event were redacted. These key words need to be revealed to confirm exactly what the testimony says.
After leaving the Navy in September 1963 Rule was an acoustic analyst for the Office of Naval Intelligence for 42 years and continued to refine his analysis of the THRESHER’s SOSUS recordings.
This is a good example of how redactions make it difficult to understand a critical part of the testimony.
Appendix A: Testimony of Mr. Bruce Rule
The following is testimony of then Lieutenant Rule, USNR found in Release 1 starting on page 206 of Commander-in-Chief, U.S. Atlantic Fleet, “Record of Proceedings of a COURT OF INQUIRY Convened at U.S. Naval Submarine Base, New London, Connecticut and Portsmouth Naval Shipyard, Portsmouth, New Hampshire,” n.d. [submitted to the U.S. Congress 24 June 1963] https://www.secnav.navy.mil/foia/readingroom/SitePages/Home.aspx under THRESHER Releases,
Bruce Rule. Yes, sir, they are True. The bearing determination of the System limits the actual bearing to a sector, bearing sector, which will have a determination within REDACTED. REDACTED so the bearings mentioned are not actually the discreet single units. A triple station contact was established on this REDACTED by subsequent contacts by the U.S. Naval Facility, Bermuda, on bearing 356, and also by Her Majesty's Canadian Ship SHELBURNE, the FOX ARRAY which terminates at this station. A position was established of 42 DEG N Latitude, 66 DEG W Longitude, with a radius of reliability of forty miles. The time of this estimated position was 101012Z. At this time and this is the corrected or absolute time, indicating an event aboard ship REDACTED, source abruptly stopped, indicating termination of a possible speed run of REDACTED this run was eighty-eight minutes and corresponds to a nearly full power run by a submarine of the THRESHER Class. The next detection on possible THRESHER source was recorded again by the REDACTED on bearing 224. The absolute event time for the previously event position was 1051Z on 10 April. Contact was maintained on this source for four minutes. Contact was then lost at 1055Z. At 1121Z, again corresponding to time aboard the ship, contact was gained on a REDACTED of THRESHER on bearing 215 from FOX, corresponding to a speed of advance of REDACTED for THRESHER Class submarines. This source indicated an RPM change at 1126Z, a very minor change, indicating a drop in speed to approximately REDACTED.
The source then diminished in strength and continued to run, point of diminution 1207Z. However, contact was maintained until approximately 1250Z; then it was lost. Contact faded out, indicating a loss of transmission rather than an actual ending of the equipment RPM aboard the vessel. The next contact was also gained by the FOX ARRAY at SHELBURNE corresponding to an absolute event time of 1237Z, the signatures believed to have been generated by the REDACTED aboard REDACTED THRESHER. The signature corresponded to those previously noted for THRESHER when the REDACTED. Again, initial contact time 1237Z. Contact was maintained on this equipment until 1411Z, when contact was lost with an abrupt stop, there is some indication on the LOFARGRAM that the equipment, rather than coming to an abrupt halt slowed very slightly in RPM's, and then contact was lost.
Question by RADM Daspit:
Q. 1411?
Bruce Rule. Yes. 0911R. This was the last contact that any station in the system had on REDACTED signature components aboard the U.S.S. THRESHER. At 101418.1Z an explosion occurred, or I will correct that to say that an acoustic disturbance occurred in the position REDACTED.