VOLUME IV

PART III

CHAPTER 6

SUBMARINE NOISE REDUCTION

REFERENCES.

(a) NAVSEA S9073-AW-SNC-010 - Ship Acoustical Surveys for Submarines

(b) NAVSEAINST C9073.2 - Acoustical Survey of Submarines

(c) COMSUBLANT/COMSUBPACINST 9460.4 - Submarine Towed Array Operations

(d) NAVSEA S9078-AA-HBK-010 - Distributed Isolation Material (DIM) Mount Design Handbook

(e) NAVSEA S9073-A2-HBK-010 - Resilient Mount Handbook

(f) Divers Pre-Deployment Noise Inspection Procedures Manual

(g) NAVEDTRA 10500 - Catalog of Navy Training Courses

(h) COMSUBLANT/COMSUBPACINST C3500.1 - Submarine Force Training Manual

LISTING OF APPENDICES.

A Supplemental Noise Measurements

B COMSUBPAC Beartrap Acoustic Radiated Trials

C Shipboard Noise Reduction Instruction

D Pre-Undocking/Deployment Under Hull Sound Silencing Survey

E Submarine Silencing Publications

F Sample Propeller Changeout Message

6.1 PURPOSE. This chapter provides the requirements for an effective onboard noise reduction program during the ship's operating cycle. It identifies the acoustic surveys required to assess the radiated noise signature of a ship and summarizes the responsibilities and requirements for the onboard surveys necessary to be performed on a regular basis to maintain the submarine in its most quiet configuration.

6.1.1 Scope. Reference (a) discusses the various acoustic surveys to be conducted on ships in order to establish their baseline noise signatures and to monitor those signatures throughout the operating cycle. Surveys discussed in reference (a) are briefly summarized, as well as several additional survey techniques available and essential to an effective noise reduction program. In addition, a discussion of the model shipboard noise reduction program and available training programs are presented.

6.1.2 Background. Reduction of the radiated noise signature of a submarine platform is a key element to the tactical employment of the ship. As a ship begins its operating cycle, a series of acoustic surveys are conducted to characterize the baseline noise signature. Then, throughout the remainder of its operating cycle, the ship requires the tools and procedures necessary to monitor its signature against the baseline. As deficiencies are identified, Ship's Force needs to have an understanding of the extent to which an identified deficiency can affect the ship's radiated noise signature and the procedures required to effect corrective action. It should be kept in mind that although the implications of a degraded noise signature are fundamentally tactical in nature, the primary method of preserving a ship's acoustic advantage is through an aggressive and effective planned and corrective noise reduction maintenance program. Because of an increased emphasis in recent years, a number of new initiatives are being pursued within the technical community to develop new and improved measurement procedures and equipment that will assist Ship's Force in more effectively assessing the effects of noise deficiencies on their radiated noise signature. These efforts should lead to improved survey procedures and will be incorporated into future changes to this chapter.

6.2 NOISE REDUCTION PROGRAM ELEMENTS.

6.2.1 Radiated Noise Surveys.

6.2.1.1 Naval Sea Systems Command Acoustic Trials. These trials are conducted at the beginning of and at various times throughout each ship's operating cycle in accordance with reference (b) and provide a broad range of baseline measurements for the ship. In particular, the radiated noise signature of the ship is measured under various operating conditions. A determination is made of the controlling radiated noise offenders including those which are speed and depth dependent. While the principal objective of these trials is to assess the radiated noise signature of the submarine, platform and machinery and hull vibration measurements are also made to provide baseline and supporting data in these areas for continued ship monitoring.

6.2.1.2 Fleet Acoustic Silencing Trials. The primary objective of these trials is to detect and identify radiated noise sources that have caused signature degradations. Signature degradations and recommended corrective actions are provided by quicklook messages. Radiated noise baseline signatures are incorporated in the final report. Specific information, including message requests and scheduling requirements as well as Ship's Force responsibilities, are contained in Appendix A of this chapter.

6.2.1.3 Coordinated Submarine Radiated Noise Analysis Exercise. This test shall be conducted in accordance with reference (c). The primary objective of these submarine-versus-submarine exercises is to collect and analyze data to assess current acoustic vulnerabilities. These tests should be conducted far enough before Pre- Overseas Movement (POM) such that deficiencies noted can be corrected during POM upkeeps. Acoustic trials conducted within six months of the start of POM can be substituted for this pre-POM acoustic check. Secondarily, they can be used during POM work-ups to verify that the deploying unit's acoustic signature is free of any unusual or highly detectable noise characteristics.

6.2.1.4 Coordinated Submarine Exercises (SECEX/SUBASWEX/SWAI). While acoustic trials and surveys are the principal means to evaluate a submarine's acoustic profile, coordinated exercises provide another opportunity for the submarine force to monitor itself for noise deficiencies. Although the primary purpose of these exercises is generally tactically oriented, the noise signature obtained can and should also serve to monitor submarine radiated noise. It is incumbent upon exercise participants to note and record any unusual or excessive radiated noise being emitted by submarine exercise participants. Discrepancies noted should be reported to the cognizant ISIC for evaluation and corrective action. Initial message reports should be followed by supporting documentation including tape recordings, annotated lofargrams, and annotated frequency spectrum analyzer X-Y plots. The message report should contain the following information:

a. Description of noise signature problem.

b. Date and time of detection.

c. Range at detection.

d. Sensor/processor used for detection.

e. Own ship depth and speed.

f. Acoustic sea state.

g. Water depth

h. Water temperature.

I. Layer depth.

6.2.1.5 Beartrap Acoustic Radiated Trials (Commander Submarine Force Pacific Submarine Only). The primary objective of these trials is to provide a cost effective means to detect and identify radiated noise sources that have caused signature degradations in lieu of a Fleet Acoustic Silencing Trials (FAST). Coordinated trial events are conducted with VP aircraft. Signature degradations and recommended corrective actions are provided by quicklook message. Radiated noise baseline signatures are incorporated in the final report. Parent ISICs are responsible for requesting these trials. Specific information, including message requests and scheduling requirements, as well as Ship's Force, SMMS PMT, and TYCOM responsibility is provided in Appendix B of this chapter.

6.2.2 Onboard Noise Surveys. The noise surveys discussed in this section do not provide conclusive information on the actual radiated noise signature of the ship. However, when these surveys are analyzed for developing trends, they can be effective tools for monitoring overall ship effectiveness in noise reduction.

6.2.2.1 Platform Noise Survey. This survey is conducted to define own ship's noise environment and is the best means available to Ship's Force to assess the radiated noise signature of the ship using only onboard equipment. Surveys are conducted by taking periodic measurements under various ship's operating conditions using the applicable PMS MRCs. In addition, at-sea watch-to-watch aural monitoring is also conducted. Analysis of this data determines the platform noise signature and also identifies the noise offenders which affect this signature. When changes in the ship's signature occur, the diagnostic procedures of the class specific platform noise manual are used to isolate the noise source. Propeller cavitation surveys should be conducted in accordance with enclosure (2b) of Appendix C of this chapter.

6.2.2.2 Topside and Housekeeping Survey. The most common and preventable sources of submarine noise are rattles emanating from improperly secured topside equipment and machinery noise sound shorted to the hull due to improper stowage below decks. The topside and housekeeping surveys consist of thorough visual inspections to identify and eliminate these potential noise sources. Particular attention should be given to ensure that sound shorts are not installed, built in, or created by repairs, alterations, or stowage.

6.2.2.3 Machinery Vibration Survey. A vibration survey conducted quarterly for both machinery health assessment and noise reduction purposes. Performance of this survey alone does not provide reliable information on radiated noise.

6.2.2.4 Hull Vibration Survey. A shipboard hull vibration survey is conducted semi-annually, during the interval between acoustic trials, by SMMS PMT or Ship’s Force. The purpose is to assess acoustic deficiencies related to noise sources and transmission paths, and to estimate certain slow-speed, low frequency radiated noise levels.

6.2.2.5 Isolation System Survey. This survey consists of a visual inspection of sound isolation components throughout the ship per applicable road maps and references (d) and (e). These components include resilient mounts, pipe hangers, ground straps, and flexible piping. This visual inspection ensures that these devices are properly installed, undamaged, and not sound shorted. Improper installation or failure of any of these devices will contribute to increasing the radiated noise signature of the ship.

6.2.2.6 Damping Material Survey. This is a visual inspection of sound damping material installed in the vicinity of sonar arrays, sail, free flood spaces, and on machinery foundations. Like the isolation system survey, this inspection is designed to detect deficiencies in materials installed to limit the radiated noise signature of the ship.

6.2.2.7 Pre-Undocking/Deployment Under Hull Survey. Requirements and forms are contained in reference (f), Appendix D of this chapter and/or MRC SO-591/901, R-3.

6.2.2.8 Technical Onboard Monitoring Assist. This survey consists of at sea analysis by acoustic technical experts to evaluate the acoustic signature of the ship. The survey consists of a towed array, platform noise hydrophones and machinery and hull vibration measurements taken simultaneously to identify and localize major acoustic degradation. Emphasis is placed on training the submarine's crew on own ship noise data acquisition and analysis using their available sensors.

6.2.3 Shipboard Noise Reduction Program. The key to a successful shipboard noise reduction program will be the ability of the ship to identify potential noise deficiencies and to initiate prompt corrective action. References listed in Appendix E of this chapter should be a part of the ship's onboard library of submarine silencing publications. Several elements of the noise reduction program are discussed in the following paragraphs.

6.2.3.1 Noise Reduction Officer. To ensure a coordinated and aggressive approach to noise reduction, each ship will assign one of its senior Department Heads, as designated by the Commanding Officer, to serve as Noise Reduction Officer. The Noise Reduction Officer will coordinate the activities of all personnel assigned to support the ship's Noise Reduction Program. This officer will ensure that all required surveys are conducted, that identified deficiencies are documented, and that corrective action is initiated. A Noise Reduction Board, chaired by the Noise Reduction Officer, will convene at regular intervals to review the status of the Noise Reduction Program. Following each meeting, formal written reports will be made to the Commanding Officer.

6.2.3.2 Noise Deficiency Log. The ship's Equipment Status Log (ESL) will be used to record and track all noise deficiencies. Deficiencies will be entered in the section for the Work Center (WC) responsible for the equipment concerned. The Critical Noise Deficiencies (NC)/Potential Noise Deficiencies (NP) code (per paragraph 6.2.3.3 below) in the deficiency description block will tag the entry as a noise deficiency. The Noise Reduction Officer will ensure the ESL is properly maintained and accurately reflects the latest status of all noise deficiencies. Items to be entered in the ESL include noise deficiencies reported during radiated noise acoustic trials as well as those discovered during onboard surveys.

6.2.3.3 Noise Related Maintenance Records. The OPNAV 4790/2K will be used to document all deferred and completed noise related maintenance actions. Block 46-G will be used to further classify noise deficiencies in one of two categories; NC and NP.

a. The NC code will be used to identify deficiencies of a critical nature identified during one of the following:

(1) NAVSEA Acoustic Trials.

(2) Other Acoustic Trials.

(3) Supplemental Radiated Noise Measurements.

(4) Platform Noise Monitoring Surveys.

(5) Technical Onboard Monitoring Assist (TOMA).

b. The NP code will be used to identify deficiencies that could potentially be radiated noise problems identified during one of the following:

(1) Topside and Housekeeping Surveys.

(2) Machinery and Hull Vibration Surveys.

(3) Isolation System Surveys.

(4) Damping Material Surveys.

(5) Airborne Sound Absorption Material Surveys.

(6) Routine Ship Operations.

6.2.4 Training. Formal training course prerequisites and descriptions are listed in reference (g). Specific training requirements are contained in reference (h).

6.3 RESPONSIBILITIES.

6.3.1 Immediate Superior In Command.

a. Assign a Staff Noise Reduction Officer as a specific point of contact for all matters relating to noise reduction within the Squadron.

b. Oversee and supervise the Noise Reduction Program within the Squadron, ensuring that assigned units aggressively identify and correct noise deficiencies.

c. Submit requests for FASTs and Beartrap Acoustic Radiated Trials (BART) to Commander Submarine Force Atlantic (COMSUBLANT)/Commander Submarine Force Pacific (COMSUBPAC) N42N, as appropriate.

d. Schedule acoustic surveys during the operating cycle of submarines in accordance with

reference (b).

e. Recommend and/or authorize corrective actions based on the findings of the surveys conducted.

f. Review Noise Reduction Program records, survey results, procedures and monitoring equipment during material readiness inspections, Tactical Readiness Evaluations and POM certification.

g. Schedule divers to conduct underwater hull and propeller surveys for noise deficiencies prior to undocking, pre-deployment, post-deployment, and during upkeep.

h. Report propeller replacements using the message format of Appendix F of this chapter.

I. Ensure that personnel tasked to support assigned submarines are adequately trained in submarine noise reduction.

6.3.2 Industrial Activity.

a. Ensure proper handling and repair of noise critical machinery.

b. Conduct in-shop and in-place balancing of all rotating equipment, both motors and coupled units, repaired by the industrial activity.

c. Conduct in-place balancing as authorized by work requests.

d. Assist ships in identifying and correcting noise problems and in conducting noise surveys in accordance with approved work requests.

e. Establish new baseline machinery and hull vibration measurement data for repaired units.

f. Ensure that all applicable personnel are adequately trained in submarine noise reduction.

g. Conduct underwater hull and propeller surveys for noise deficiencies in accordance with

reference (f).

6.3.3 Submarine Commanding Officer.

a. Establish and maintain a ship's Noise Reduction Program consistent with this chapter. Appendix C of this chapter provides the basis for a shipboard instruction to meet this requirement.

b. Appoint a senior Department Head as Noise Reduction Officer and establish a Ship's Noise Reduction Board.

APPENDIX A

SUPPLEMENTAL NOISE MEASUREMENTS

This Appendix provides a brief discussion of the TYCOM sponsored, noise measurements that may periodically be conducted on submarines during their operating cycle.

COMSUBLANT FLEET ACOUSTIC SILENCING TRIALS

1. Purpose. FASTs provide Atlantic Fleet submarines with the opportunity to obtain a measurement of their radiated noise signature periodically during their operating cycle in order to check for potential degradations, determine sources of any new acoustic deficiencies, and evaluate improvements resulting from corrective actions.
2. Procedure. FASTs are scheduled by COMSUBLANT N42N. The tests are conducted by Naval Surface Warfare Center, Carderock Division (NSWCCD) at Exuma Sound or the Atlantic Underwater Test and Evaluation Center. Testing consists of a series of runs past a suspended hydrophone array in accordance with the FAST agenda prepared specifically to collect the data required to address the radiated noise characteristics of interest. FAST trials are conducted on a 24 hour basis and ships should request a 24 hour Special Broadcast Arrangement.
3. Frequency. COMSUBLANT N42N will schedule FASTs for SSN 637 and SSN 640 Class submarines after every SRA and for all other submarines on an as needed basis.
4. Reports. NSWCCD will issue a quicklook message within ten working days of completion of a FAST. A final detailed report will be issued within 35 days of completion of a FAST.
5. Action. Ship's Force should use the Maintenance and Material Management (3-M) Maintenance Data System to document deficiencies and corrective actions. For deferred items, the ship's Noise Reduction Officer should develop and implement appropriate corrective action.

COMSUBPAC FLEET ACOUSTIC SILENCING TRIALS

1. Purpose. FASTs are conducted on Pacific Fleet submarines in order to assess their radiated noise signatures, identify problems, and provide an opportunity to correct deficiencies prior to deployment.
2. Procedure. FASTs are initially scheduled by COMSUBPAC prior to major deployments or upon request by the submarine's ISIC. The ISIC is then responsible for updating the schedule. Tests are conducted by NSWC Detachment Puget Sound with the support of Naval Underwater Weapons Engineering Station Detachment Lualualei. FASTs consist of a series of runs conducted on either the instrumented range at the Barking Sands Tactical Underwater Range, Southeast Alaska Acoustic Measurement Facility, or the Santa Cruz Acoustic Range Facility in accordance with the FAST agenda which is prepared to collect the data required to assess the mission readiness of the ship. Depending on requirements, FASTs normally take 12 to 24 hours to complete data collection.
3. Frequency. ISICs should coordinate FAST scheduling for their submarines such that each ship will be tested prior to the POM availability. This schedule will allow corrective action to be taken on noise deficiencies detected during the FAST.
4. Reports. NSWC Detachment Puget Sound will issue a quicklook message, normally within 48 hours of completion of a FAST. This message will detail significant findings and recommended corrective action. A final detailed report of the trial will be issued within 30 days of completion of a FAST.
5. Action. Ship's Force and the submarine's ISIC should use the results and recommendations of the FAST quicklook and final report to schedule and implement corrective action for noise deficiencies detected during the trial. For deferred items the Noise Reduction Officer should develop and implement appropriate corrective action.

TECHNICAL ONBOARD MONITORING ASSIST

1. Purpose. TOMAs are conducted on submarines to maintain their acoustic signatures between scheduled radiated noise trials. Major acoustic degradations and their corrective actions are identified, and training is provided to Ship's Force.
2. Procedure. TOMAs are initially scheduled by the TYCOMs on an annual basis. TOMAs are conducted by NSWC, with assistance from on-site PMT and Ship's Force personnel. TOMAs need about 48 hours of data acquisition time. Normally, TOMAs are conducted on three to seven day underways and can be scheduled concurrently with other operations. Tests consist of a series of runs in various machinery line ups to collect data required to assess the acoustic signature of the submarine. Data is collected using onboard sensors and compared to baseline signatures from previous acoustic trials. A TOMA will serve as a semiannual hull survey as well as the quarterly machinery vibration survey.
3. Frequency. TOMAs are to be conducted annually when no radiated noise trial is scheduled, or when requested by the submarine's ISIC.
4. Reports. NSWC will issue a quicklook message from the submarine at the completion of the TOMA. This message will detail significant findings and recommended corrective actions, as well as the status of previous corrective actions. A separate message will be sent by NSWC detailing machinery vibration data.
5. Action. Ship's Force and the submarine's ISIC should use the results and recommendations of the TOMA quicklook message to schedule and implement corrective action. Ship's Force should use the 3-M Maintenance Data System to document deficiencies and corrective actions. For deferred items, the Noise Reduction Officer should develop and implement appropriate corrective action.

APPENDIX B

COMSUBPAC BEARTRAP ACOUSTIC RADIATED TRIALS

1. Purpose. BARTs are conducted in lieu of FASTs and provide Pacific Fleet submarines with the opportunity to measure and assess their radiated noise signatures, identify problems, and provide an opportunity to correct deficiencies and evaluate their acoustic health prior to certain deployments.
2. Procedure. BARTs are initially scheduled by COMSUBPAC prior to major deployments or upon request by the submarines's ISIC. The ISIC is then responsible for updating the schedule. BARTs consist of dockside inspections and underway inspections and tests including an LOS and a structured Beartrap in a designated quiet ocean area in accordance with the BART agenda to collect sufficient data to determine the radiated noise signature and mission readiness of the ship. Dockside and sea testing is performed by Ship's Force, supported by SMMS PMT Teams and the COMSUBPAC Sound Silencing Representative. Data collection on station is accomplished by Commander Patrol Wing Southern Pacific (COMPATWINGSPAC) Anti Submarine Warfare patrol aircraft and is restricted to a single eight hour period during ship operations in a designated ocean area.
3. Frequency. ISICs should coordinate BART scheduling for their submarines such that each ship will be tested prior to the pre-POM availability. This schedule will allow sufficient time for corrective action on noise deficiencies detected during the BART to be planned and accomplished during the POM upkeep period.
4. Reports. COMSUBPAC will issue a quicklook message, normally within 48 hours of completion of a BART. The message will detail significant finding and recommended corrective action. A final detailed report of the trial will be issued by COMSUBPAC within 30 days of completion of a BART.
5. Action. Ship's Force and the submarine's ISIC should use the results and recommendations of the BART quicklook and final report to schedule and implement corrective action for noise deficiencies detected during the trial. For deferred items the Noise Reduction Officer should develop and implement appropriate corrective action.

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APPENDIX C

SHIPBOARD NOISE REDUCTION INSTRUCTION

USS (Ship's Name and Hull No.)

Subj: SHIP'S NOISE REDUCTION PROGRAM

Ref: (a) CINCLANTFLT/CINCPACFLTINST 4790.3; Joint Fleet Maintenance Manual, Volume IV, Part III, Chapter 6

Encl: (1) Quarterly Noise Reduction Program Status Report

(2) Noise Reduction Surveys

(3) Control Surface Noise Questionnaire

1. Purpose. To establish a ship's Noise Reduction Program to include: a Noise Reduction Board to advise the Commanding Officer concerning appropriate noise reduction procedures; a set of noise surveys to characterize the ship's noise signature; and procedures to ensure proper coordination of efforts in the ship's noise reduction program.
2. Discussion. A great deal of emphasis has been placed on upgrading noise reduction awareness within the submarine force. As required by reference (a), (Ship's Name) must devote continued attention to the detection, correction and prevention of increases in its radiated noise signature. Significant mission degrading radiated noise problems could not be tolerated in war time. (Ship's Name) must minimize noise to maximize our detection range of threats/targets and to reduce the possibility of hostile ships detecting (Ship's Name). Quietness is absolutely essential to our primary mission and a continuous, aggressive effort must be made in acoustic housekeeping and noise reduction to ensure a quiet ship. The acoustic surveys considered mandatory for effectively maintaining a quiet ship and improving the ship's acoustic signature during the operating cycle are discussed in this instruction. While these surveys serve as a formal means of noise reduction, each crew member's actions play an equally important role in the noise reduction consciousness of the entire ship. A quiet ship requires involvement of the whole crew. THINK QUIET!
3. Program Organization.

a. A ship's Noise Reduction Board shall be established to assist the Commanding Officer in the development and execution of long and short range plans for maintaining and enhancing the acoustic posture of the ship. The board will recommend appropriate shipboard noise reduction procedures and monitor their execution. The board will consist of the following personnel:

(1) Executive Officer.

(2) Combat Systems Officer.

(3) Engineer Officer.

(4) Sonar Officer.

(5) Electrical Officer.

(6) First Lieutenant.

(7) Sonar Division Leading Petty Officer.

(8) Electrical Division Noise Reduction Petty Officer (NRPO).

(9) Chief of the Boat.

b. To assist the board in carrying out their responsibilities, experienced Petty Officers and non-rated personnel who have completed qualification in submarines shall be assigned in the ship's collateral duties notice as NRPO. Each division will have at least one formally designated NRPO.

4. Program Management.

a. The Noise Reduction Officer will coordinate all noise reduction activities within the ship. The Noise Reduction Board will meet periodically (before and after each upkeep and at least monthly underway) and discuss actions completed and further action required to correct outstanding noise deficiencies. The Noise Reduction Officer will chair these meetings. The Noise Reduction Officer will ensure that the noise reduction portion of the ESL contains updated entries on all outstanding noise deficiencies. Each of the significant noise deficiencies will be discussed at every meeting. The Commanding Officer will be apprised of the results of the meeting and any unresolved problems shortly after the meeting. Formal written reports summarizing the status of the Noise Reduction Program will be submitted following each meeting to the Commanding Officer using the format of enclosure (1).

b. Onboard surveys will be conducted in accordance with this instruction. Noise deficiencies discovered during these surveys or detected during routine ship's operations will be reported to the Noise Reduction Officer. At sea, these reports will be made to the OOD who will, in turn, inform both the Noise Reduction Officer and the Commanding Officer. The OOD will initiate corrective action for all significant noise deficiencies and ensure that these items are included in the watch turnover. All deficiencies that are not immediately correctable will be entered in the noise deficiency section of the ESL.

c. The Noise Reduction Officer shall ask the following questions during each Noise Reduction Board meeting.

(1) Have we effected all corrective action recommendations from our latest acoustic trials? Have on board measurement surveys conclusively proven that outstanding noise deficiencies were corrected? Report all unresolved items to the Commanding Officer using the format of enclosure (1).

(2) Have any noise sources, especially rattles or control surface transients, been aurally detected during the conduct of the platform noise survey of enclosure (2a)? If rattles or transients are present, have tape recordings or data packages been accomplished in accordance with platform noise or maintenance manual guidance for submission?

(3) Have we conducted a propeller tip cavitation survey in accordance with enclosure (2b)? Are the measured tip cavitation points acceptable?

(4) Have any signature degradations been identified from the latest set of towed array, platform noise hydrophone or machinery and hull vibration measurements? If so, have the noise sources been identified? Report unresolved items to the Commanding Officer using the format of enclosure (1).

5. Action.

a. The Executive Officer shall:

(1) Attend all Noise Reduction Board meetings.

(2) Implement a comprehensive, all hands training program to elevate the awareness of Ship's Force personnel to the importance of noise reduction.

b. The Noise Reduction Officer shall:

(1) Coordinate and administer the ship's Noise Reduction Program.

(2) Schedule Noise Reduction Board meetings and chair their meetings.

(3) Report the status of noise deficiencies to the Commanding Officer following meetings of the Noise Reduction Board. Submit written summary reports to the Commanding Officer using the format of enclosure (1).

(4) Ensure that cognizant divisions enter all noise reduction deficiencies in the ESL, that prompt corrective action is taken by responsible divisions and that work requests are submitted for deficiencies beyond the capability of Ship's Force.

(5) Ensure that acoustic trial deficiencies are entered in the ESL and that appropriate corrective action is initiated.

(6) Assess the tactical implications of noise deficiencies detected during underway operations and make recommendations to the Commanding Officer as to tactical limitations and required corrective action.

(7) Ensure that cognizant divisions have men properly trained in Ship's Force acoustic surveys, noise reduction equipment, proper bearing replacement, and in-place balancing of rotating equipment.

(8) Ensure that surveys are being conducted by cognizant divisions and that deficiencies are reported to the Commanding Officer.

(9) Conduct spot reviews of acoustic survey results.

(10) Be inventory manager of all publications required by reference (a), to support the Noise Reduction Program and ensure that divisions have applicable MRCs.

(11) Assist the Engineer Officer with the implementation and maintenance of the ship's quiet bills.

(12) Ensure action is taken, to the maximum extent possible, to complete enclosure (3) for all identified control surface noises.

c. The Sonar Officer shall:

(1) Ensure that the Platform Noise Survey is accomplished, recorded, and analyzed in accordance with enclosure (2a).

(2) Perform Propeller Cavitation Noise Surveys as required in accordance with enclosure (2b).

(3) Develop propeller cavitation curves in accordance with enclosure (2b) and forward results to the Commanding Officer via the Noise Reduction Officer.

(4) Direct the use of the installed sonar systems to assist in the identification and isolation of noise related material deficiencies detected in Topside, Housekeeping, Machinery and Hull Vibration, and Isolation System Surveys. (Enclosures 2c, 2d, 2e, and 2f respectively refer).

(5) Ensure that Damping Material Surveys are accomplished, recorded, and analyzed in accordance with enclosure (2g).

(6) Report immediately any abnormal increase in own ship's noise to the OOD and the Noise Reduction Officer.

(7) Ensure that all survey deficiencies are entered in the noise reduction section of the ESL and reported to the Noise Reduction Officer. Ensure that prompt corrective action is taken and that work requests are submitted for deficiencies beyond the capability of Ship's Force.

(8) Ensure that personnel assigned to conduct noise reduction surveys under his cognizance are properly trained.

d. The Electrical Officer shall:

(1) Ensure that the Machinery and Hull Vibration Surveys are accomplished, recorded, and analyzed in accordance with enclosure (2e).

(2) Ensure that in-place balancing is conducted on an assembled unit at any time that repairs are made by Forces Afloat that would affect the balance of the equipment.

(3) Determine the cause of out of specification machinery and hull vibration readings and initiate corrective action.

(4) Ensure that prompt corrective action is taken and that work requests are submitted for deficiencies beyond the capability of Ship's Force.

(5) Ensure that personnel under his cognizance assigned to conduct noise reduction surveys are properly trained.

e. The First Lieutenant shall:

(1) Ensure that the Topside and Housekeeping Surveys are accomplished, recorded, and analyzed in accordance with enclosure (2c) and (2d).

(2) Ensure that the Airborne Sound Absorption Material Survey is accomplished, recorded, and analyzed in accordance with enclosure (2h).

(3) With the assistance of the Supply Officer, ensure that equipment, stores, personal effects, and consumables are stowed in a manner that will not produce noise or transmit noise to the ship's hull or structure.

(4) Ensure that all survey deficiencies are entered in the noise reduction section of the ESL and reported to the Noise Reduction Officer. Ensure that prompt corrective action is taken and that work requests are submitted for deficiencies beyond the capability of Ship's Force.

(5) Ensure that personnel under his cognizance assigned to conduct noise reduction surveys are properly trained.

f. The NRPO shall:

(1) Promote the Noise Reduction Program in their respective divisions.

(2) Perform or assist in the performance of noise reduction surveys under their respective division's cognizance in accordance with enclosure (2).

(3) Enter all survey deficiencies in the noise reduction section of the ESL and report deficiencies to the cognizant Division Officer.

g. The OOD shall:

(1) Remain aware of the status of critical noise deficiencies and operate the ship in a manner that will minimize its radiated noise signature.

(2) Report all new noise deficiencies and the correction of existing deficiencies to the Noise Reduction Officer and the Commanding Officer. Ensure new deficiencies are recorded in the noise reduction section of the ESL.

(3) Ensure sonar watchstanders conduct aural monitoring of own ship's noise signature upon initial dive and once per watch.

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From: Noise Reduction Officer

To: Commanding Officer

Via: Executive Officer

Subj: QUARTERLY NOISE REDUCTION PROGRAM STATUS REPORT FOR PERIOD ENDING (DATE)

Encl: (1) Noise Reduction Section of ESL

1.The following MRs associated with the Noise Reduction Program were not accomplished, partially accomplished, or deferred:

MRC No./Deficiency reason/Corrective Action

2.The following noise deficiencies were identified during the current period:

Deficiency/Source/ESL No.

3.The following previously identified noise deficiencies were corrected during the current period:

Deficiency/Corrective Action

4.Enclosure (1) summarizes all currently outstanding deficiencies associated with the Noise Reduction Program.

Submitted:

Noise Reduction Officer

Copy to:

Engineer Officer

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NOISE REDUCTION SURVEYS

1.This enclosure contains a description of the onboard surveys conducted in support of the Noise Reduction Program. For each survey, applicable references are cited and a summary of procedures and reporting requirements are presented. Surveys included are:

Enclosure 2a Platform Noise Survey

2b Propeller Cavitation Noise Survey

2c Topside Survey

2d Housekeeping Survey

2e Machinery and Hull Vibration Survey

2f Isolation System Survey

2g Damping Material Survey

2h Sound Absorption Material Survey

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PLATFORM NOISE SURVEY

Reference: (a) Class Applicable Technical Manual for Platform Noise Monitoring Analysis for Noise Reduction

(b) Class Applicable SO-544 MIP/MRCs

(c) OPNAVINST 5513.5A Department of the Navy (DON) Security Classification Guidance for Undersea Warfare Programs

1. Responsibility. Sonar Officer.
2. Procedure.

a. Platform Noise Surveys shall be conducted as specified in references (a) and (b).

b. Sonar supervisors shall monitor each hydrophone on each band and through the unfiltered outputs of the AN/BQA-8 for objectionable noises at least once each watch while underway and report results to the OOD. Problems detected shall also be recorded in the Noise Reduction section of the ESL. Problem investigation and corrective action shall be initiated as soon as possible within the current operations schedule.

c. As soon as feasible, after diving, following an inport period, accomplish the following:

(1) Monitor each band and the unfiltered outputs of each AN/BQA-8 hydrophone for objectionable noise while changing speed in five knot increments up to Flank speed. At slow speed, monitor hydrophones nearest the rudder/stern planes and fairwater planes while each control surface is cycled. Monitor the hydrophone nearest the sail while each mast and antenna is cycled. Complete the applicable portions of the Control Surface Noise Questionnaire, enclosure (3), to report control surface noise. This questionnaire assists in troubleshooting.

(2) Check at least one point of the propeller cavitation curve. If results are significantly different from the previous data, establish a new cavitation curve at the earliest opportunity as discussed in enclosure (2b).

(3) If operations preclude complete accomplishment of (1) and (2) above, speeds/ areas not monitored should be noted and carried forward in the sonar supervisor's log until they can be monitored.

(4) Results of this monitoring will be reported to the OOD and deficiencies recorded in the ESL.

d. For any abnormal noises, magnetic tape recordings should be made in accordance with the propeller, shaft and bearing noise section of reference (a). These tape recordings together with complete supporting data shall be forwarded by priority registered mail second day delivery to:

For COMSUBLANT units: Carderock Division

Naval Surface Warfare Center

Bethesda, Maryland 20084-5000

Attn: Code 713

For COMSUBPAC units: Director, Naval Surface Warfare Center

Carderock Division Detachment Puget Sound

Attn: Code 713

Bremerton, Washington 98314-5215

Units should request analysis and recommendations for corrective action from NSWC. The response will be provided by message within 24 hours of receipt of the data package.

e. Platform noise hydrophone recordings are classified CONFIDENTIAL in accordance with reference (c), (Encl 55). Improperly classifying these tapes SECRET will delay analysis due to more stringent handling requirements.

3.Frequency. Surveys will be conducted as specified within this instruction, reference (a) and applicable MRCs. Additional surveys will be conducted as required to support noise reduction efforts related to other shipboard surveys or whenever such monitoring is required for the identification of noise degradations or to verify the effectiveness of corrective actions.

4.Record. Survey results will consist of platform noise spectra, cavitation data, and entries to the ESL and Sonar Line Log. Records will be kept as specified within this instruction, in reference (a) or as required to meet the needs of noise reduction efforts aboard ship.

5.Review. The Sonar Officer will review results of all surveys weekly and the Noise Reduction Officer will review all records in conjunction with Noise Reduction Board meetings monthly.

PROPELLER CAVITATION NOISE SURVEY

Reference: (a) Class Applicable Technical Manual for Platform Noise Monitoring Analysis for Noise Reduction

(b) COMSUBDEVRON TWELVE, Submarine Tactics, Vol VII, No. 1, March 1986

1. Responsibility. Sonar Officer.
2. Procedure. Propeller cavitation surveys and diagnostic procedures will be conducted as specified in reference (a). Propeller cavitation curves will be developed using the procedural guidance of reference (a), for the various tactical considerations specified in reference (b).
3. Frequency. Since the ship's operating schedule dictates the frequency at which propeller cavitation surveys can be made, no specific frequency can be assigned. However, a complete cavitation survey should be made after any CNO Maintenance Availability or upkeep period. One point of the current cavitation curve should be verified at the beginning of each underway period. If results are significantly different, a complete new curve should be developed.
4. Unacceptable Propeller Tip Cavitation Performance. Propeller replacement due to poor acoustic performance is based solely on unacceptable tip cavitation as determined by NSWCCD (Division or Detachment Bremerton) personnel. Ships with emergent poor tip cavitation performance should immediately record and forward cavitation curve tapes in accordance with the Platform Noise Survey Section of this Appendix.
5. Reports. The original and the five most recent cavitation curves will be retained and compared for trend analysis until the propeller is changed.
6. Review. The Sonar Officer shall compare new cavitation curves to previous ones and forward the results to the Commanding Officer via the Noise Reduction Officer.

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TOPSIDE SURVEY

Reference: (a) MRC SO-591-R1

1. Responsibility. First Lieutenant.
2. Procedure. The First Lieutenant shall ensure that the following items are accomplished in accordance with reference (a):

a. Open and inspect all line lockers and free flood areas for loose gear and other sources of noise, such as loose zincs, rattling pipes, loose grates, etc.

b. Check all deck hatches to ensure they shut properly and will not rattle.

c. Check that all towed array fairing plates are properly secured (if applicable).

d. Check all cleats for proper operation and ensure that they do not rattle when stowed.

e. Check stowage of all portable equipment topside to ensure that proper gasket material is installed, all bolts and wing nuts are present, and equipment is securely held in place when mounted.

f. When required, inspect sail area for loose gear and sources of rattles. Particular attention should be given to the mast bearings and operating equipment to ensure that masts will not be damaged or fouled. Before reinstalling sail plates, the sail should be inspected by the Noise Reduction Officer.

3.Frequency. A complete Topside Survey, including the sail, shall be conducted after any major upkeep or inport period, or whenever major topside work is completed. A sail closeout inspection shall be conducted by an officer prior to the reinstallation of any sail plate removed. Surveys should be completed as far in advance of underway as possible. Other inspections shall be conducted as directed by the First Lieutenant.

4.Reports. A written report in memorandum form shall be submitted to the Commanding Officer at the completion of each inspection. This report shall include, as a minimum, the date the inspection was made, names of personnel conducting the inspection and uncorrected discrepancies noted in the ESL. Reports shall be routed via the Noise Reduction Officer, with copies to cognizant Department Heads.

5.Review. The results of each inspection shall be reviewed by the First Lieutenant and retained until all discrepancies are corrected.

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HOUSEKEEPING SURVEY

Reference: (a) MRC SO-591-R2

1. Responsibility. Noise Reduction Officer.
2. Procedure. It is the responsibility of the NRPO to inspect their division's spaces in accordance with reference (a) for sound shorts or other silencing discrepancies which may result from improper stowage of loose gear.
3. Frequency. Improper stowage is a continuous problem and should be monitored as such. It is the responsibility of all hands to monitor the stowage of all gear and to ensure that sound shorts are not created by improper stowage. OODs, EOOWs and all watchstanders are required by other instructions to inspect various spaces. These inspections should include monitoring for proper stowage and possible sound shorts. Prior to getting underway, all divisions must inspect their spaces for proper stowage at sea. Division Officers should acknowledge by signature on respective pre-underway check sheets that their spaces are stowed for sea.
4. Reports. Potential sound short discrepancies will be reported to the OOD who will inform the Commanding Officer and responsible Department Heads, to ensure that problems are corrected. Discrepancies not immediately corrected shall be noted in the ESL.
5. Review. The Noise Reduction Officer shall review all pre-underway check sheets and maintain a record of all noise discrepancy items until corrected.

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MACHINERY AND HULL VIBRATION SURVEY

Reference: (a) Class Applicable Technical Manual for Machinery and Hull Vibration Testing and Monitoring of SSN/SSBN Auxiliary Machinery

(b) MIP EL-035/903 Vibration Noise Monitoring

1. Responsibility. Electrical Officer.
2. Procedure. Machinery and hull vibration surveys shall be conducted as specified in reference (a) and in accordance with applicable PMS (reference (b)). Items found to be out-of-specification will be logged in the ESL as potential noise deficiencies. Machinery and hull vibration surveys are conducted on all submarines.
3. Frequency.

a. A comprehensive machinery and hull vibration survey should be conducted quarterly by the PMT or Ship's Force. Specific machinery and hull vibration monitoring surveys shall be conducted by Ship's Force bi-weekly on selected equipment identified in the NSWC Detachment, Annapolis or Bremerton, machinery Vibration Deficiency Message and as required to support onboard noise reduction efforts.

b. A comprehensive machinery and hull vibration survey should be conducted semi-annually by the PMT or Ship's Force. Results are forwarded to the applicable NSWC Detachment via the PMT.

4.Reports.

a. NSWC Detachment, Annapolis, Maryland; NSWC Detachment, Bremerton, Washington, evaluate and maintain machinery and hull vibration data collected by the PMTs or Ship's Force. They report out-of-specification equipment or hull vibration levels via message.

b. During each machinery and hull vibration survey, a report is submitted to the appropriate NSWC Detachment via the local PMT. This report shall include the sound cut data and a feedback package.

c. For the Hull Vibration Monitoring Program, a message should be sent from the submarine to the appropriate NSWC Detachment within 45 days of receipt of the NSWC Detachment hull vibration deficiency message or when operationally feasible. This message should include the results of actions taken to identify and correct the sources of excessive hull vibration levels and to identify platform noise sources.

5.Noise Reduction Training. Crew training in noise awareness and noise reduction is absolutely essential to maintaining a quiet ship. The Submarine Force Training Manual discusses formal training courses and requirements pertaining to noise reduction as well as materials available for onboard training.

6.Review. The Electrical Officer shall review and forward the results of all machinery and hull vibration measurements to the Commanding Officer via the Noise Reduction Officer and Executive Officer. This report shall be submitted within five working days of the survey and shall include a listing of which noise measurements have been taken and any out-of- specification equipment.

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ISOLATION SYSTEM SURVEY

Reference: (a) NAVSEA S9073-AW-SNC-010/(U) Ship Acoustical Surveys

(b) NAVSEA S9073-AF-SNC-010/(C), Ship Noise Control

(c) Appropriate Noise Control Guidelines, Road Maps, and Equipment Guide Lists

(d) Appropriate MIP SO-593 MRCs

1. Responsibility. Noise Reduction Officer.
2. Procedure. For SSN 637 and SSN 640 Class submarines the Noise Reduction Officer shall require Ship's Force to conduct a visual inspection of silencing equipment and components such as resilient mounts, flexible pipe, pipe hangers, ground straps, electrical connections, etc., to ensure they are properly installed, within periodicity, undamaged and not shorted. References (a), (b), (c) and (d) apply. For SSN 688 and SSBN 726 Class submarines, these inspections will be conducted by a NAVSEA designated activity.
3. Frequency. For SSN 637 and SSN 640 Class submarines those ship systems which have mounts constantly exposed to a hot or oily environment should be surveyed annually and after equipment change out. All other sound isolated systems should be inspected every 60 months and after equipment change out. For SSN 688 and SSBN 726 Class submarines, a complete isolation system survey will be performed every 60 months by a NAVSEA designated activity. Ship's Force should inspect systems after equipment change out.
4. Reports. The Noise Reduction Officer shall ensure that all defects found are logged in the ESL and shall report survey results to the Commanding Officer within five working days of completion of the inspection.
5. Review. The Noise Reduction Officer shall maintain a record of all discrepancies noted until corrected.

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DAMPING MATERIAL SURVEY

Reference: (a) NAVSEA S9073-AW-SNC-010/(U), Ship Acoustical Surveys

(b) MIP SO-592/001 Damping Material Survey

(c) NAVSEA S9072-AF-SNC-010/(C), Ship Noise Control

1. Responsibility. Sonar Officer.
2. Procedure. The Sonar Officer shall ensure that a thorough inspection is conducted of all damping material installed in sonar array areas, fairwater, main ballast tanks, and free flood areas, to ensure that no deterioration has taken place in accordance with the guidance provided in references (a) and (b). Reference (c) provides specific information relating to these materials.
3. Frequency. A Damping Material survey shall be conducted as specified with reference (b) or at each dry-docking, in accordance with reference (a).
4. Reports. A written report in memorandum form shall be submitted for each inspection and shall include, as a minimum, the date of inspection, names of personnel conducting the inspection, and the discrepancies noted in the ESL.
5. Review. The Sonar Officer shall review the results of each inspection and forward them to the Commanding Officer via the Noise Reduction Officer within five working days of the completion of the inspection. This report shall be retained by the Noise Reduction Officer until all discrepancies have been corrected.

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SOUND ABSORPTION MATERIAL SURVEY

Reference: (a) NAVSEA S9073-AW-SNC-010/(U), Ship Acoustical Surveys

(b) NAVSEA S9073-AF-SNC-010/(C), Ship Noise Control

1. Responsibility. First Lieutenant.
2. Procedure. The First Lieutenant will ensure that a thorough inspection of the interior sound absorption and sound transmission loss material is conducted in all spaces. This inspection ensures that no deterioration of these materials has taken place. This inspection is accomplished with guidance from reference (a), while reference (b) provides specific information relating to these materials.
3. Frequency. A Sound Absorption Material Survey shall be conducted prior to each major CNO Maintenance Availability. An inspection of any system affected by maintenance or other work shall be conducted following completion of the work.
4. Reports. A written report in memorandum form will be submitted to the Noise Reduction Officer for each inspection and will include, as a minimum, the date of the inspection, names of personnel conducting the inspection, and discrepancies noted in the ESL.
5. Review. The First Lieutenant will review the results of each inspection and forward them to the Commanding Officer via the Noise Reduction Officer within five working days of the completion of the inspection. This report will be retained by the Noise Reduction Officer until all discrepancies have been corrected.

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CONTROL SURFACE NOISE QUESTIONNAIRE

1.The purpose of this questionnaire is to provide more accurate and definitive information than reports of "noise in the fairwater" or "noise in the mud tank". This information can reduce troubleshooting time, prevent unnecessary maintenance, and perhaps prevent an unnecessary and unscheduled dry-docking. It can also furnish vital data to assist in the resolution of a problem and prevent its recurrence.

Hull Number: Date:

Check the appropriate box or fill in the blanks in response to the questions below:

Note 1: Grease underway if the appropriate alteration is installed to permit remote greasing of the stern planes and rudder connecting rods. The fairwater/bow connecting rod may be greased locally while underway on the surface even if remote greasing alteration is not installed.

Note 2: If the stern planes are suspected of causing the noise and the noise did not diminish after greasing the stern plane components, grease the rudder components. If the greasing did not help a suspected noisy rudder, grease the stern planes.

Deliver this questionnaire to the PMT if your next port has a local PMT. Otherwise, mail this questionnaire to your Squadron PMT upon arrival inport. The PMT will provide appropriate distribution to NAVSEA PMS 350, PMS 390, PMS 393, PMS 396, TYCOM, and ISIC.

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APPENDIX D

PRE-UNDOCKING/DEPLOYMENT UNDER HULL

SOUND SILENCING SURVEY

1. Purpose. To provide requirements for Pre-Undocking/Pre-Deployment Under Hull Sound Silencing Surveys.
2. Policy. This Appendix establishes the requirements for the Under Hull Sound Silencing Survey of all submarines.
3. Under Hull Sound Silencing Surveys. Under Hull Sound Silencing Surveys of submarines (using reference (f)) will be done at the following times:

a. Prior to the ship leaving dry-dock.

b. Waterborne Under Hull Inspection during the first week of a scheduled upkeep, normally accomplished by the inspecting facilities divers.

c. Waterborne Under Hull Inspection prior to deployments of 30 days or greater, normally accomplished by the inspecting facilities divers.

4. Reports. The Senior Hull Inspector of the inspecting facility will conduct an inspection critique for the ship's Noise Reduction Officer and ISIC Material Officer. Copies of the final survey report (a format is provided on the following page) or SO-591/901, R-3 data sheets will be supplied by the inspecting facility to the submarine and cognizant ISIC Material Officer.

SOUND SILENCING SURVEY REPORT

1.Inspection performed by:

Senior Inspector:

Inspector #1

Inspector #2

Inspector #3

Inspector #4

2. The following deficiencies were noted:

3. Submitted by:

APPENDIX E

SUBMARINE SILENCING PUBLICATIONS

Note 1 : Specific MRs for consideration in this listing are for:

a. Inspect, clean & replace sound washers.

b. Record machinery vibration levels.

c. Record hull vibration levels.

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APPENDIX F

SAMPLE PROPELLER CHANGEOUT MESSAGE

FM COMSUBRON (AS APPROPRIATE)//

TO COMNAVSEASYSCOM WASHINGTON DC//05F3/393/396//

INFO COMSUBPAC PEARL HARBOR HI//N42N/N402//

COMSUBLANT NORFOLK VA//N42N/N402//

USS (SHIP'S NAME AND HULL NO.)//

BT

UNCLAS //N09245//

MSGID/GENADMIN/COMSUBRON (AS APPROPRIATE)//

SUBJ/(SUBS) PROPELLER CHANGEOUT//

REF/A/DOC/CINCLANTFLT/CINCPACFLTINST 4790.3//

NARR/REF A IS JOINT FLEET MAINTENANCE MANUAL/VOL IV, PT III, CH 6 PROVIDES GUIDANCE FOR MONITORING PROPELLER VIBRATION DATA AND PROPELLER CHANGE OUT//

RMKS/1. IAW REF A, FOL PROPELLER DATA REPORTED

A. SERIAL NO. OF PROPELLER REMOVED

B. SERIAL NO. OF PROPELLER INSTALLED

C. REASON PROPELLER REPLACED

(POOR PERFORMANCE, EXCESSIVE CAVITATION, GOUGED/NICKED, SINGING SCREW, ETC.)

2. REQUEST DISPOSITION INSTRUCTIONS FOR REMOVED PROPELLER//

BT

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