Attachment_6_USCG_Safe_Operating_Envelope_Full-Scale_Trials_Results_July_2016_-_Final_RFP.pdf

U.S. Department o~- Hometand Security •·®, United States Coast Guard

United States Coast Guard Commandant (CG-9325)

MEMORANDUM

From: V.~~~:-=x COMD~~&i V

Subj: AUTHORIZATION TO POST

2703 Martin Luther King Jr. Ave SE Stop 7800 Washington, DC 20593-7800 Staff Symbol: CG-731/CG-9325 Phone: (202) 475-5808

26 NOV 2019

NSWCCD TECHNICAL REPORT NSWCCD-80-TR-2016/019

USCG SAFE OPERATING ENVELOPE FULL-SCALE TRIALS RESULTS

l. Naval Surface Warfare Center, Carderock Division, Combat Craft Division, completed a technical report for the U.S. Coast Guard docwnenting the characteristics and performance of two U.S Coast Guard owned boats. Identified with a Scientific and Technical Information (STINFO) distribution Statement F, further dissemination of the report is at the discretion of the Coast Guard Office of Boat Acquisition, (CG-9325).

2. I have approved public release and dissemination of this report.

Naval Surface Warfare Center

Carderock Division

West Bethesda, MD 20817-5700

NSWCCD-80-TR-2016/019 July 2016

Naval Architecture and Engineering Department

Technical Report

USCG SAFE OPERATING ENVELOPE FULL-SCALE

TRIALS RESULTS

by

Ryan J. Faber and Jayson Q. Bautista

NSWCCD

DISTRIBUTION STATEMENT F: Further dissemination only as directed by Commandant, USCG (CG-9325), 2703 Martin Luther King Jr Ave SE, US Coast Guard Stop 7800, Washington, DC 20593-7800 (July 2016) or higher CG/DoD authority.

Destruction notice for unclassified documents, destroy by any method that will prevent disclosure of contents or reconstruction of the document. N

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REPORT DOCUMENTATION PAGE

Form Approved

OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202- 4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

1. REPORT DATE (DD-MM-YYYY)

07-29-2016

2. REPORT TYPE

Final

3. DATES COVERED (From - To)

4. TITLE AND SUBTITLE

USCG Safe Operating Envelope Full-Scale Trials Results

5a. CONTRACT NUMBER

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

Faber, Ryan J.

Bautista, Jayson, Q.

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

HSCG2313XACB011

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

NAVSEA, Naval Surface Warfare Center

Carderock Division, Combatant Craft Division

2600 Tarawa Court, Suite 303

Virginia Beach, VA 23459-3239

8. PERFORMING ORGANIZATION REPORT

NUMBER

NSWCCD-80-TR-2016/019

9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S)

United States Coast Guard

Cutter Boat Acquisition CG-9325

2703 Martin Luther King Jr Ave SE, US Coast Guard Stop 7800

Washington, DC 20593-7800

11. SPONSOR/MONITOR’S REPORT

NUMBER(S)

12. DISTRIBUTION / AVAILABILITY STATEMENT

DISTRIBUTION STATEMENT F: Further dissemination only as directed by Commandant, USCG (CG-

9325), 2703 Martin Luther King Jr Ave SE, US Coast Guard Stop 7800, Washington, DC 20593-

7800 (July 2016) or higher CG/DoD authority

13. SUPPLEMENTARY NOTES

14. ABSTRACT

Trials were conducted on United States Coast Guard Over the Horizon (OTH-IV) 26253 and

Long Range Interceptor (LRI-II) 35106 between October and December of 2015 in Norfolk, VA.

Trials documented the craft calm-water properties at speed and at rest. Rough water trials documented the craft motions while drifting and running at three speeds in five directions to the seas. Additional trials were conducted on OTH-IV in-air to obtain mass properties of the craft.

15. SUBJECT TERMS

USCG OTH-IV LRI-II Seakeeping Powering Scale Weighing In-Air Inclining In-Air

Roll In-Water Inclining Roll Period Pitch Period Safe Operating Envelope

16. SECURITY CLASSIFICATION OF:

17. LIMITATION

OF ABSTRACT

18. NUMBER

OF PAGES

19a. NAME OF RESPONSIBLE PERSON

Ryan J. Faber

a. REPORT

Unclassified

b. ABSTRACT

Unclassified

c. THIS PAGE

Unclassified

SAR

19b. TELEPHONE NUMBER (include area code)

(757)288-4281

Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18

NSWCCD-83-TM-2013/40

ii

NSWCCD-80-TR-2016/019

iii

CONTENTS

SYMBOLS, ABBREVIATIONS, AND ACRONYMS ................................................................ xi

ADMINISTRATIVE INFORMATION ...................................................................................... xiii

ACKNOWLEDGEMENTS ......................................................................................................... xiii

SUMMARY ................................................................................................................................. xiv

INTRODUCTION

Background

Load Conditions

Crew and Passenger Weights

Light Ship Weight Condition

OTH-IV Performance Weight Condition

LRI-II Performance Weight Condition

METHODS, ASSUMPTIONS, AND PROCEDURES

Scale Weighing

In-Air Inclining

In-Air Roll Period

In-Water Inclining

In-Water Pitch Period

In-Water Roll Period

Calm-Water Powering

Seakeeping

Beam Sea Roll Response Drift Test

RESULTS AND DISCUSSION

OTH-IV Scale Weighing

LRI-II Weight Survey

OTH-IV In-Air Inclining

OTH-IV In-Air Roll Period

In-Water Inclining iv

OTH-IV

LRI-II

In-Water Roll and Pitch Period

OTH-IV Roll Period

OTH-IV Pitch Period

LRI-II Roll Period

LRI-II Pitch Period

Calm-Water Powering

OTH-IV

LRI-II

Seakeeping

Seakeeping Sea State 4 Conditions

OTH-IV Sea State 4 Seakeeping at a Nominal Speed of 6 knots

OTH-IV Sea State 4 Seakeeping at a Nominal Speed of 12 knots

OTH-IV Sea State 4 Seakeeping at a Nominal Speed of 25 knots or MAX Safe Speed .. 41

LRI-II Sea State 4 Seakeeping at a Nominal Speed of 6 knots

LRI-II Sea State 4 Seakeeping at a Nominal Speed of 12 knots

LRI-II Sea State 4 Seakeeping at a Nominal Speed of 25 knots or MAX Safe Speed

Seakeeping Sea State 3 Conditions

OTH-IV Sea State 3 Seakeeping at a Nominal Speed of 6 knots

OTH-IV Sea State 3 Seakeeping at a Nominal Speed of 12 knots

OTH-IV Sea State 3 Seakeeping at a Nominal Speed of 25 knots or MAX Safe Speed .. 60

LRI Sea State 3 Seakeeping at a Nominal Speed of 6 knots

LRI Sea State 3 Seakeeping at a Nominal Speed of 12 knots

LRI-II SS3 Seakeeping at a Nominal Speed of 25 knots or MAX Safe Speed

Beam Sea Roll Response Drift Test

OTH-IV

LRI-II

CONCLUSIONS AND RECOMMENDATIONS

REFERENCES

APPENDIX A: USCG SAFE OPERATING ENVELOPE VIDEO & DATA

(transferred as a separate deliverable)......................................................................................... A-1

APPENDIX B: OTH-IV IN-AIR ROLL PERIOD TIME HISTORIES ..................................... B-1 v

APPENDIX C: OTH-IV IN-WATER ROLL PERIOD TIME HISTORIES ............................. C-1

APPENDIX D: OTH-IV IN-WATER PITCH PERIOD TIME HISTORIES ............................ D-1

APPENDIX E: LRI-II IN-WATER ROLL PERIOD TIME HISTORIES .................................. E-1

APPENDIX F: LRI-II IN-WATER PITCH PERIOD TIME HISTORIES ................................. F-1 vi

FIGURES

Figure 1. LRI-II (background) and OTH-IV (foreground)

Figure 2. OTH-IV Light Ship Scale Weighing

Figure 3. Forward (left) and Aft (right) Lift Fittings

Figure 4. Forward Lifting Point Knife Edge Design

Figure 5. Aft Lifting Point Knife Edge Design

Figure 6. Knife Edge Load Testing

Figure 7. In-Air Incline and Roll Period Configuration

Figure 8. Incline Weight Movements

Figure 9. In-Water Pitch Period Configuration

Figure 10. In Water Pitch Period of LRI-II

Figure 11. Calm-Water Performance Trials Location

Figure 12. National Instruments CompactRIO Data Acquisition System

Figure 13. Rough Water Trials Location including NDBC 44099 and CHLV2

Figure 14. Seakeeping Star Pattern

Figure 15. OTH-IV Craft Motions Measurement Locations

Figure 16. LRI-II Craft Motions Measurement Locations

Figure 17. Seakeeping Sign Convention

Figure 18. Roll Event to Starboard Where Craft is Listing to Port

Figure 19. OTH-IV In-Air Inclining Weight Movements and Resulting Heel Angles

Figure 20. OTH-IV In-Air Inclining Plot of Moments and Tangents

Figure 21. OTH-IV In-Air Roll Period Test 1 Time History

Figure 22. OTH-IV In-Water Inclining Weight Movements and Resulting Heel Angles

Figure 23. OTH-IV In-Water Inclining Plot of Moments and Tangents

Figure 24. LRI-II In-Water Inclining Weight Movements and Resulting Heel Angles

Figure 25. LRI-II In-Water Inclining Plot of Moments and Tangents

Figure 26. OTH-IV In-Water Roll Period Test 1 Time History

Figure 27. OTH-IV Pitch Period Test 1 Time History

Figure 28. LRI-II In-Water Roll Period Test 1 Time History vii

Figure 29. LRI-II Pitch Period Test 1 Time History

Figure 30. OTH-IV Calm Water Powering Results

Figure 31. LRI-II Calm Water Powering Results

Figure 32. LCG Vertical Acceleration in Head Seas Expanded to Show Identified Peaks

Figure 33. LRI-II and OTH-IV in Sea State 3 (Chesapeake Light Tower in Background)

Figure 34. LRI-II and OTH-IV in Sea State 4

Figure 35. OTH-IV 6 Knot Sea State 4 LCG Vertical Accelerations

Figure 36. OTH-IV 12 Knot Sea State 4 LCG Vertical Accelerations

Figure 37. OTH-IV 25 Knot or MAX Safe Speed Sea State 4 Vertical Accelerations

Figure 38. LRI-II 6 Knot Sea State 4 LCG Vertical Accelerations

Figure 39. LRI-II 12 Knot Sea State 4 LCG Vertical Accelerations

Figure 40. LRI-II 25 Knot or MAX Safe Speed Sea State 4 LCG Vertical Accelerations

Figure 41. OTH-IV 6 Knot Sea State 3 LCG Vertical Accelerations

Figure 42. OTH-IV 12 Knot Sea State 3 Vertical Accelerations

Figure 43. OTH-IV 25 Knot or MAX Safe Sea State 3 LCG Vertical Accelerations

Figure 44. LRI-II 6 Knot Sea State 3 LCG Vertical Accelerations

Figure 45. LRI-II 12 Knot Sea State 3 LCG Vertical Accelerations

Figure 46. LRI-II 25 Knot or MAX Safe Speed Sea State 3 LCG Vertical Accelerations

Figure 47. OTH-IV Sample Time History of Roll Angles during Drift Test

Figure 48. OTH-IV Drift Test Sea State 4 Roll Angles Histograms

Figure 49. OTH-IV Drift Test Sea State 3 Roll Angles Histograms

Figure 50. LRI-II Drift Test Sea State 4 Roll Angles Histograms

Figure 51. LRI-II Drift Test Sea State 3 Roll Angles Histograms viii

TABLES

Table 1. USCG SOE Test Results Summary

Table 2. NATO Sea State Numerical Table for the Open Ocean North Atlantic

Table 3. LRI-II Weight Survey

Table 4. OTH-IV In Air Inclining Test Results

Table 5. OTH-IV In-Air Roll Period Test Results

Table 6. OTH-IV In-Water Inclining Test Results

Table 7. LRI-II In-Water Inclining Test Results

Table 8. OTH-IV In-Water Roll Period Test Results

Table 9. OTH-IV In-Water Pitch Period Test Results

Table 10. LRI-II In-Water Roll Period Test Results

Table 11. LRI-II In-Water Pitch Period Test Results

Table 12. OTH-IV Calm-Water Powering Results

Table 13. LRI-II Calm-Water Powering Results

Table 14. Wave Statistics Recorded at NDBC Station 44099 for Sea State 4

Table 15. OTH-IV 6 Knot Head Seas Run in Sea State 4

Table 16. OTH-IV 6 Knot Port Quarting Seas Run in Sea State 4

Table 17. OTH-IV 6 Knot Starboard Beam Seas Run in Sea State 4

Table 18. OTH-IV 6 Knot Port Bow Seas Run in Sea State 4

Table 19. OTH-IV 6 Knot Following Seas Run in Sea State 4

Table 20. OTH-IV 12 Knot Head Seas Run in Sea State 4

Table 21. OTH-IV 12 Knot Port Quartering Seas Run in Sea State 4

Table 22. OTH-IV 12 Starboard Beam Seas Run in Sea State 4

Table 23. OTH-IV 12 Knot Port Bow Seas Run in Sea State 4

Table 24. OTH-IV 12 Knot Following Seas Run in Sea State 4

Table 25. OTH-IV 25 Knot or MAX Safe Speed Head Seas Run in Sea State 4

Table 26. OTH-IV 25 Knot or MAX Safe Speed Port Quartering Seas Run in Sea State 4

Table 27. OTH-IV 25 Knot or MAX Safe Speed Starboard Beam Seas Run in Sea State 4

Table 28. OTH-IV 25 Knot or MAX Safe Speed Port Bow Seas Run in Sea State 4 ix

Table 29. OTH-IV 25 Knot or MAX Safe Speed Following Seas Run in Sea State 4

Table 30. LRI-II 6 Knot Head Seas Run in Sea State 4

Table 31. LRI-II 6 Knot Port Quartering Seas Run in Sea State 4

Table 32. LRI-II 6 Knot Starboard Beam Seas Run in Sea State 4

Table 33. LRI-II 6 Knot Port Bow Seas Run in Sea State 4

Table 34. LRI-II 6 Knot Following Seas Run in Sea State 4

Table 35. LRI-II 12 Knot Head Seas Run in Sea State 4

Table 36. LRI-II 12 Knot Port Quartering Seas Run in Sea State 4

Table 37. LRI-II 12 Knot Starboard Beam Seas Run in SS4

Table 38. LRI-II 12 Knot Port Bow Seas Run in Sea State 4

Table 39. LRI-II 12 Knot Following Seas Run in Sea State 4

Table 40. LRI-II 25 Knot or MAX Safe Speed Head Seas Run in Sea State 4

Table 41. LRI-II 25 Knot or MAX Safe Speed Port Quartering Seas Run in Sea State 4

Table 42. LRI-II 25 Knot or MAX Safe Speed Starboard Beam Seas Run in Sea State 4

Table 43. LRI-II 25 Knot or MAX Safe Speed Port Bow Seas Run in Sea State 4

Table 44. LRI-II 25 Knot or MAX Safe Speed Following Seas Run in Sea State 4

Table 45. Wave Statistics Recorded at NDBC Station 44099 for Sea State 3

Table 46. OTH-IV 6 Knot Head Seas Run in Sea State 3

Table 47. OTH-IV 6 Knot Port Quarter Seas Run in Sea State 3

Table 48. OTH-IV 6 Knot Starboard Beam Seas Run in Sea State 3

Table 49. OTH-IV 6 Knot Port Bow Seas Run in Sea State 3

Table 50. OTH-IV 6 Knot Following Seas Run in Sea State 3

Table 51. OTH-IV 12 Knot Head Seas Run in Sea State 3

Table 52. OTH-IV 12 Knot Port Quartering Seas Run in Sea State 3

Table 53. OTH-IV 12 Knot Starboard Beam Seas Run in Sea State 3

Table 54. OTH-IV 12 Knot Port Bow Seas Run in Sea State 3

Table 55. OTH-IV 12 Knot Following Seas Run in Sea State 3

Table 56. OTH-IV 25 Knot or MAX Safe Speed Head Seas Run in Sea State 3

Table 57. OTH-IV 25 Knot or MAX Safe Speed Port Quartering Seas Run in Sea State 3

Table 58. OTH-IV 25 Knot or MAX Safe Speed Starboard Beam Seas Run in Sea State 3

Table 59. OTH-IV 25 Knot or MAX Safe Speed Port Bow Seas Run in Sea State 3

Table 60. OTH-IV 25 Knot or MAX Safe Speed Following Seas Run in Sea State 3

Table 61. LRI-II 6 Knot Head Seas Run in Sea State 3 x

Table 62. LRI-II 6 Knot Port Quartering Seas Run in Sea State 3

Table 63. LRI-II 6 Knot Starboard Beam Seas Run in Sea State 3

Table 64. LRI-II 6 Knot Port Bow Seas Run in Sea State 3

Table 65. LRI-II 6 Knot Following Seas Run in Sea State 3

Table 66. LRI-II 12 Knot Head Seas Run in Sea State 3

Table 67. LRI-II 12 Knot Port Quartering Seas Run in Sea State 3

Table 68. LRI-II 12 Knot Starboard Beam Seas Run in Sea Sea State 3

Table 69. LRI-II 12 Knot Port Bow Seas Run in Sea State 3

Table 70. LRI-II 12 Knot Following Seas Run in Sea State 3

Table 71. LRI-II 25 Knot or MAX Safe Speed Head Seas Run in Sea State 3

Table 72. LRI-II 25 Knot or MAX Safe Speed Port Quartering Seas Run in Sea State 3

Table 73. LRI-II 25 Knot or MAX Safe Speed Starboard Beam Seas Run in Sea State 3

Table 74. LRI-II 25 Knot or MAX Safe Speed Port Bow Seas Run in Sea State 3

Table 75. LRI-II 25 Knot or MAX Safe Speed Following Seas Run in Sea State 3

Table 76. OTH-IV Drift Test Results

Table 77. LRI-II Drift Test Results xi

SYMBOLS, ABBREVIATIONS, AND ACRONYMS

ANSI .................................................................................... American National Standards Institute

CAN .......................................................................................................... Controller Area Network

CCD ......................................................................................................... Combatant Craft Division cRIO ..................................................................................... compact Reconfigurable Input Output

DC .................................................................................................... Direct Current, also zero Hertz deg ........................................................................................................................................... degree

Dp .............................................................................................................. Dominant wave direction

F ....................................................................................................................................... Fahrenheit

FIR ............................................................................................................. Finite Impulse Response ft ........................................................................................................................................... foot/feet fwd ........................................................................................................................................ forward g............................................................................................................... acceleration due to gravity gal ........................................................................................................................................ gallon(s) gph............................................................................................................................gallons per hour hp............................................................................................................. Global Positioning System hr ................................................................................................................................................ hour

Hs ................................................................................................................. significant wave height

Hz .............................................................................................................................................. Hertz

ISO .......................................................................... International Organization for Standardization kn............................................................................................................................................ knot(s) lb ......................................................................................................................................... pound(s)

LCG.................................................................................................. Longitudinal Center of Gravity

MEMS ........................................................................................ Microelectromechanical System(s) mV....................................................................................................................................... milliVolt

NDBC .................................................................................................... National Data Buoy Center nmi ............................................................................................................................nautical mile(s)

NSWCCD DN ................. Naval Surface Warfare Center Carderock Division Detachment Norfolk xii

PPE .................................................................................................. Personal Protection Equipment

RMQ ...................................................................................................................... Root Mean Quad

RMS .....................................................................................................................Root Mean Square rpm .............................................................................................................. Revolutions Per Minute

.............................................................................................................. sigma (standard deviation) sec ...................................................................................................................................... second(s) stbd ...................................................................................................................................... starboard

Ta ..................................................................................................................... average wave period

TDMS ................................................................................ Technical Data Management Streaming

Tp .......................................................................................................................... peak wave period

WAAS ......................................................................................... Wide Area Augmentation System xiii

ADMINISTRATIVE INFORMATION

United States Coast Guard (USCG) Cutter Boat Acquisition, CG-9325 tasked the Naval

Surface Warfare Center, Carderock Division, Detachment Norfolk (NSWCCD DN) to conduct full-scale trials on USCG Cutter Boat Over the Horizon-IV (OTH-IV) and USCG Cutter Boat

Long Range Interceptor-II (LRI-II). Tasking includes preparation of a test plan, performance of the test, presentation of overall results in a test report, and release of raw data collected via sensors and video cameras to USCG Surface Forces Logistics Center to help determine Safe

Operating Envelopes (SOEs) for OTH-IV and LRI-II. This report presents the results of trials conducted between October and December 2015 in the Norfolk, VA area. Funding for this effort was provided under MIPR HSCG2313XACB011.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the coordination and overall assistance of CG-9325 employees Mark Porvaznik and Jack Welsh and CG-7321 employee Dave Shepard. Recognition is extended to Seaward Services Inc. employees who provided support for boat movements and lifts as well as material fabrication. The authors are indebted to the crew of the United States

Coast Guard Cutter Hamilton for their active role in operating OTH-IV and LRI-II through all rough-water and calm-water test events as well as the Response Boat Medium crews from

Station Little Creek in Virginia Beach, VA.

xiv

SUMMARY

Trials were conducted on USCG OTH-IV 26253 and USCG LRI-II 35106 between

October and December 2015 in Norfolk, Virginia. These trials included rough-water motion, calm-water speed and trim, and roll and pitch period decay tests in accordance with USCG Safe

Operating Envelope Full-Scale Trials Test Plan, NSWCCD-83-TM-2015/54. Additionally, an in-air incline, swing test, two-point scale weighing and in-water incline was performed on OTH-

IV and an in-water incline was performed on LRI-II. Data collected from these trials have been provided to USCG Surface Forces Logistics Center to help determine Safe Operating Envelopes

(SOEs) for OTH-IV and LRI-II.

All tests were performed with the boats in the performance-load condition. In this condition OTH-IV had a nominal displacement of 8,630 pounds with a longitudinal center of gravity (LCG) approximately 7.8 feet forward of the transom-keel intersection. In the performance-load condition, LRI-II had a displacement of 20,310 pounds with a LCG approximately 11.1 feet forward of the transom-baseline intersection.

From an in-air incline and swing test, OTH-IV had a vertical center of gravity of 2.69 feet above the keel and in-air roll period of 2.5 seconds. From in-water inclines OTH-IV and LRI-II had metacentric heights of 2.3 and 3.5 feet respectively. Measured values of damped roll and pitch of OTH-IV was 2.0 seconds and 2.3 seconds. For LRI-II, the damped roll period was 2.5 seconds and damped pitch period was 2.6 seconds.

OTH-IV achieved an average maximum speed of 37.6 knots in calm water at an average engine speed of 3,338 rpm. Hydrodynamic running trim at this speed was 2.5 degrees referenced to the keel forward of the single-water jet delta pad. LRI-II achieved an average maximum speed of 39.6 knots in calm water at an average engine speed of 3,307 rpm. Hydrodynamic running trim at this speed was 1.9 degrees referenced to the keel and delta pad.

Rough-water motion data was collected with OTH-IV and LRI-II operating in sea state 3 and sea state 4 at 6, 12, and 25 knots, if 25 knots of speed could not be attained the maximum safe speed as determined by the USCG coxswain. In sea state 3 the significant wave height ranged between 3.6 to 4.0 feet with an average period ranging between 4.5 and 4.9 seconds. The dominant period was between 10.0 and 11.0 seconds from 078 to 113 degrees true north. In sea state four the significant wave height ranged between 5.3 to 6.0 feet with an average period ranging between 5.5 and 6.2 seconds. The dominant period was between 7.0 and 9.0 seconds from 085 to 093 degrees true north. Data was acquired as the craft was operated in five directions relative to the prevailing sea at 6, 12, and 25 knots or maximum (MAX) safe speed.

Analysis of vertical accelerations at the craft’s LCG indicated an average of the 1/10 th highest accelerations of 4.35 g in a head sea at an average speed of 24.7 knots, in sea state 3, for OTH-IV and 2.23 g in a head sea at an average speed of 24.3 knots, in sea state 3, for LRI-II. In sea state

4, vertical accelerations at the craft’s LCG indicated an average of the 1/10 th highest accelerations of 2.66 g in a head sea at an average speed of 20.6 knots for OTH-IV and 2.19 g in a head sea at an average speed of 23.5 knots for LRI-II.

All raw boat motion and mass properties data as well as wave buoy data collected is provided as a reference. Video of the tests was captured to document the testing and is provided as a reference. Table 1 summarizes test data gathered during the trials period.

Table 1. USCG SOE Test Results Summary

Test Measurement

Boat / Test Condition

OTH-IV

Performance Load

LRI-II

Performance Load

Displacement and LCG 8,630 lb @ 7.8 ft 20,310 lb @ 11.1 ft

Maximum Calm Water speed

37.6 kn @ 3,338 rpm 39.6 kn @ 3,307 rpm

Running Trim at Maximum Speed

2.5 deg 1.9 deg

S e a S ta te

T h re e

Significant Wave Height 3.6 – 4.0 ft

Average Wave Period 4.5 – 4.9 sec

Dominant Wave Period 10.0 – 11.0 sec

Dominant Wave Direction 78 – 113 deg True

A1/10 Vertical Acceleration at the LCG 4.35 g 2.23 g

Drifting Average Roll Period 2.4 sec 2.8 sec

Drifting Maximum Roll Angle -13.3 deg, 16.4 deg -14.6 deg, 15.8 deg

Drifting Mode Roll Angle -2 deg, 5 deg -5 deg, 6 deg

S e a S ta te

F o u r 3

Significant Wave Height 5.3 - 6.0 ft

Average Wave Period 5.5 – 6.2 sec

Dominant Wave Period 7.0 – 9.0 sec

Dominant Wave Direction 85 – 93 deg True

A1/10 Vertical Acceleration at the LCG

2.66 g 2.19 g

Drifting Average Roll Period 2.4 sec 2.8 sec

Drifting Maximum Roll Angle -13.9 deg, 15.5 deg -17.0 deg, 17.2 deg

Drifting Mode Roll Angle -1 deg, 7 deg -3 deg, 5 deg In

-W a te r 2

Damped Roll Period 2.0 sec 2.5 sec

Damped Pitch Period 2.3 sec 2.6 sec

GM from Incline 2.3 ft 3.5 ft

In -A ir 5

Vertical Center of Gravity 2.69 ft

Roll Period 2.5 sec

Pendulum Length 3.30 ft

Roll Moment of Inertia 1590 lb-ft

Roll Gyradius 2.44 ft

1. LCG and trim measurements referenced to the transom-keel intersection.

2. Results were obtained in calm-water conditions.

3. Sea state as defined by NATO Sea State Numerical Table for the Open North Atlantic, see Table 2.

4. VCG referenced to the keel forward of the delta pad on OTH-IV and to the keel and delta pad on LRI-II.

5. Results obtained in a building with no wind effects.

INTRODUCTION

Trials on OTH-IV and LRI-II were conducted in general accordance with USCG Safe

Operating Envelope Full-Scale Trials Test Plan, NSWCCD-83-TM-2015/54 [1]. The overall goal of this test effort was to document the motions of the boats in Sea State 3 and 4 running at various speeds and headings as well as drifting to aid the USCG’s Surface Forces Logistics

Center effort to determine safe operating envelopes for OTH-IV and LRI-II. Additional efforts focused on obtaining the damped roll and pitch period of the craft in calm water and to document the running trim and calm water properties through various engine speeds. Also an in-water inclining was performed to find the metacentric height. Finally, an in-air inclining and swing test was performed on OTH-IV to obtain vertical center of gravity and in air roll period.

This report presents the results of measurements acquired during the safe operating envelope trials on OTH-IV and LRI-II. Background information is provided to describe the craft and test displacement conditions. Trials methods are presented for each measurement along with assumptions and a description of the instrumentation used to make the measurement. The results of each test are presented and discussion is provided to expand on important topics.

Background

USCG is refining the process for determining the operational limits for current and future boats. The Surface Forces Logistics Center Engineering Services Division (SFLC-ESD) intends to use full-scale trials and model testing to validate computer modeling and simulations to predict boat motions and provide recommended operating limits. Two representative USCG cutter boats were identified for the full and model-scale testing, and subsequent computer modeling and simulations: OTH-IV and LRI-II are shown in Figure 1. This report documents the full-scale testing NSWCCD DN performed with the USCG on OTH-IV and LRI-II on the east coast.

Figure 1. LRI-II (background) and OTH-IV (foreground)

Load Conditions

Testing was conducted in the performance weight conditions. These conditions are defined below:

Crew and Passenger Weights

The crew and passenger weights were considered 220 pounds per person which included

Personal Protective Equipment (PPE) in accordance with the OTH-IV and LRI-II acquisition documents. Ballast was used to compensate.

Light Ship Weight Condition

The Light Ship Weight Condition was defined as the craft complete and ready for service in every respect including outfit. Liquids in machinery were at operating levels. This condition did not include crew, fuel, or cargo for both vessels.

OTH-IV Performance Weight Condition

The Performance Weight Condition was the Light Ship Weight Condition with full fuel, crew of three plus two boarding team members in their seats and 150 pounds of cargo in the aft cargo storage compartments. This condition did not include the weight of the removable ballistic protection components.

LRI-II Performance Weight Condition

The Performance Weight Condition was the Light Ship Weight Condition with full fuel, crew of five and 150 pounds of cargo. This condition does not include the weight of the removable ballistic protection components.

METHODS, ASSUMPTIONS, AND PROCEDURES

A number of measurements and tests were conducted throughout the trials period to characterize the craft’s physical properties and overall performance. Craft displacements for each craft were determined by either a scale weighing and/or a weight survey. An in-air inclining was performed on OTH-IV and an in-water inclining was performed on OTH-IV and

LRI-II to determine the metacentric height (GM) of each craft. An in-air swing test was performed to determine the roll period of OTH-IV which can be used to calculate the roll moment of inertia. In-water roll and pitch decay tests were performed on both OTH-IV and LRI-

II to determine the damped roll and pitch period of each craft. Calm-water powering trials defined the relationships between craft speed, engine speed, engine loading, trim, and fuel consumption. Seakeeping measurements characterized the craft’s motions in a seaway in two separate sea states for three speeds and five headings to the sea. Finally, roll measurements while adrift in sea state 3 and sea state 4 with the craft beam to the dominant sea direction characterized the craft’s roll response in a seaway.

Weight surveys were conducted throughout the trials to establish the craft’s loading condition. The weight surveys included measured or estimated weights and locations of onboard outfit items, personnel, ballast, fuel level, and bilge fluids before, during, and after trials.

Scale Weighing

Following delivery from the builder, OTH-IV was trailered to NSWCCD DN’s test facility.

The shrink wrap was removed and all spare parts and outfit were inventoried. Spares were stored at the test facility and items considered a part of the outfit were stored onboard.

Following installation of data and video acquisition packages, OTH-IV was scale-weighed to determine the craft’s weight and LCG. The craft had minimal fuel onboard and no water in the bilges. The boat was considered to be in the Light Ship Weight Condition with the exception of the test equipment. A two-point lift was conducted to scale weigh OTH-IV as shown in Figure

2. A 6,000 lb and 25,000 lb fork truck suspended two 10,000 lb digital load cells with shackles and endless round slings at the top and bottom of the load cells. Before the load cells and rigging were connected to the craft, the load cell was zeroed so that the weight displayed would not include the weight of the rigging. This rigging was then connected to the forward and aft lift points on OTH-IV and the boat was lifted. For each weighing, the craft was lifted clear from the bunks of its trailer, and then the keel was leveled using a digital inclinometer on the boat, which referenced the keel. For each lift a sufficient time, approximately 2 minutes, was given to allow the craft and measurements to stabilize. Three separate lifts were performed to ensure repeatability of the measurements. Locations of the forward and aft lift points were recorded for determining LCG.

Figure 2. OTH-IV Light Ship Scale Weighing

The OTH-IV was then configured in the Performance Weight Condition. The port and starboard tanks were filled until fuel was in the fill line. Lead ballast was secured in and on-top of the shock mitigating seats, and additional lead ballast was added so that the test equipment and ballast amounted to 150 lbs of cargo. Any water in the bilges was removed by vacuum and then dried. Again 6,000 lb and 25,000 lb fork trucks were employed to weigh OTH-IV using a

5,000 lb and 10,000 lb capacity load cells in a two-point lift configuration using the craft’s forward and aft lift points. Load cells were zeroed with the rigging attached before lifting the boat. For each weighing, the craft was lifted clear from the bunks of its trailer and then the keel was leveled using a digital inclinometer on the boat, which referenced the keel. For each lift a sufficient time, approximately 2 minutes, was given to allow the craft and measurements to stabilize. Three separate lifts were performed to ensure repeatability.

The 10,000 lb load cells used during the scale weighing’s have a reported accuracy of 0.1% of capacity, or 10 pounds and display resolution of 0.1% capacity, or 10 pounds. The 5,000 lb load cell used at the forward lift point for the Performance Load Condition scale weighing has a reported accuracy of 10 pounds.

In-Air Inclining

In-air incline experiments aim to suspend the craft above from rigid knife edges and allow the boat to rotate in roll when heeling moments are applied. In practice however, fabricating knife edges and suspending the craft with rigging has been problematic in the past and has led to uncertainty in the measurements. OTH-IV 26253 has fixed forward and after lifting rings that alleviate many of the rigging issues observed in prior in-air incline experiments.

The existing forward and aft lift fittings were not parallel with the keel. To ensure the boat rotated correctly about the forward and aft lift fittings, a new larger and taller lift eye was designed and sent to a machine shop for fabrication. This new forward lift fitting was fabricated so that both lift fittings were parallel with the keel. The existing forward lift fitting was removed and then the keel was leveled using the trailer tongue jack and a digital inclinometer. A water tube was fixed on the aft lift fitting and run forward to the forward lift fitting where it was dry fit.

The new forward lift fitting mounting holes were drilled out on a bench press and bolted to the boat so the forward lift fitting was exactly the same height as the aft lift fitting relative to a level keel. Figure 3 shows the forward and aft lift fittings and the water tube used.

Figure 3. Forward (left) and Aft (right) Lift Fittings

Significant time was spent designing and fabricating knife edges specifically for lifting

OTH-IV. Many aspects between the interface with the boat and the fork trucks used to lift the boat were considered and incorporated into the design. The load to be lifted at each knife edge, the fork trucks capacity and boom extension, the material properties of the knife edge, the amount of swing anticipated, and the inside diameter of the lift fittings were just some of these considerations. Figure 4 and Figure 5 show the finalized knife edge designed and fabricated by

NSWCCD DN. Each knife edge was then load tested as shown in Figure 6. Testing was done to verify that the knife edges would perform as designed and that a load would oscillate freely.

Figure 4. Forward Lifting Point Knife Edge Design

Figure 5. Aft Lifting Point Knife Edge Design

Figure 6. Knife Edge Load Testing

Figure 7. In-Air Inclining and Roll Period Configuration

An in-air inclining was performed on OTH-IV in the performance-weight condition. The vertical center of gravity (VCG) was determined by moving weights transversely across the craft’s deck to induce a heeling moment as shown in Figure 8. From the known moment and tangent of inclination and the known craft displacement, the metacentric height (GM) was calculated. Since the metacentric height was fixed via knife edges, the keel to the knife edge was measured using laser measurement to give the distance between the keel and the metacenter

(KM). Subtracting GM from KM yielded KG or the vertical center of gravity.

Solid steel inclining weights were used to make adjustments to the heel angle of the craft suspended in air. Figure 8 shows those weight movements and how they were positioned to obtain heel angles. This permitted observations of several inclining moments to port and starboard giving a satisfactory linear regression trend line. Inclining angles were measured using

NSWCCD DN’s onboard data acquisition system.

Figure 8. Inclining Weight Movements

In-Air Roll Period

An in-air roll period test was performed on OTH-IV. The same knife edge setup and data acquisition system was used as in the in-air inclining test, shown in Figure 7. For each measurement, the craft was suspended by the knife edges and the keel leveled using the fork trucks. A test engineer pushed on the side of the craft to start it rolling and then released it. An onboard data acquisition system was used to capture roll time history. The time between each maximum starboard roll angle was used to determine the roll period. The roll moment of inertia about the principal axis passing through the center of gravity can be calculated by [2]:

g drp T

Wd

CG

I

2|

Where:

d = distance from the axis of rotation to the principal axis passing through the CG

W= weight of the craft

Trp = measured roll period g = gravitational acceleration

The roll gyradius can be calculated by

[2]:

d rp T gdk

In-Water Inclining

An in-water inclining experiment was performed on OTH-IV and LRI-II to determine the craft’s GM. The inclinings were conducted with the craft loaded to the performance-weight condition. In order to minimize free surface effects the fuel tanks were pressed full. For OTH-IV additional weight was added to the boat and moved to produce heel angles in the performance weight condition. For LRI-II, weights used to ballast the boat to the performance weight condition were moved to produce heel angles.

Inclining weights consisted of solid steel blocks which were used so adjustments to roll moments and angles were possible. A quantity of six 100 lb-weight blocks were moved on

OTH-IV and a quantity of six 200 lb-weight blocks were moved on LRI-II. For OTH-IV the same weight movements that were used for the in-air inclining were performed for the in-water inclining. Figure 8 shows these weight movements which permitted observations of several inclining moments to port and starboard giving a linear regression trend line. Inclining angles were measured using the onboard data acquisition system.

In-Water Pitch Period

Prior to performing the in-water pitch period test a 25,000 lb-fork truck was fitted with a boom extension. Off the boom extension, a load cell and quick release was attached and known weights were lifted in 1,000 lb-increments up to 5,000 lbs. and dropped on the ground to ensure no unknown dynamic effects would be imparted into the fork truck. Then the fork truck was positioned and chocked at the edge of a quay wall at NSWCCD DN’s test facility. OTH-IV and

LRI-II were then positioned bow to the wall and connected to the fork truck. Figure 9 shows configuration of the fork truck, boom extension, load cell, quick release, and connection to the boat used for the in water pitch tests. Using the dedicated readout on the load cell and real time trim angle, the bow of each boat was lifted in increasing increments and then allowed to drop using the inline quick release. For OTH-IV, approximately 500 lb-increments were used up to

2,500 lbs. and for LRI-II; approximately 1,000 lb-increments were used up to 5,000 lbs. Prior to release, line handlers positioning the boat under the fork truck slacked the mooring lines so as not to affect the measurements. Initial trim angle was recorded as well as the pitch period of the boat at 50 samples per second. Following a drop of the bow, the boat would pitch down then back up and continue to oscillate. At no time did the bows impact the quay wall. A time history of this oscillation was recorded and used to measure the damped pitch period. Figure 10 shows a pitch period test of LRI-II.

Figure 9. In-Water Pitch Period Configuration

Figure 10. In Water Pitch Period of LRI-II

In-Water Roll Period

In-water roll periods were initially performed on OTH-IV and LRI-II by the classic method of inducing roll by moving crew weight transversely. However, on LRI-II another way was created by the Coast Guard coxswain at the helm. He used the joystick to induce a rolling motion by alternating thrust from the waterjets to induce roll without making headway and then allowing the joystick and waterjet thrust to go to neutral as the boat oscillated in roll. This method produced larger initial roll angles and additional roll oscillations before decay. On OTH-

IV, moving crew weight was initially tried but another method proved to provide larger roll angles and additional roll oscillations before decay. This other method involved test engineers pushing down on the lifelines from a floating dock coinciding with the period of the boat then releasing the lifelines and measuring damped roll period. This proved more effective as the distance off centerline was greater and produced a larger roll moment. Roll angles were sampled at 50 samples per second to produce well defined time histories of the roll, which were post-processed to find the local maximum roll angles and define the time between them to find damped roll period.

Calm-Water Powering

Calm-water performance trials were conducted in Hampton Roads near NSWCCD DN’s test facility. Water depths in the trials area averaged 50 feet. Testing was conducted to characterize the relationships between craft speed and trim. In addition engine data was collected including engine speed, percent load, and fuel consumption.

Figure 11 is a chart showing the general area of calm-water performance trials.

Figure 11. Calm-Water Performance Trials Location

Calm-water powering trials data was acquired in the Performance Weight for both OTH-IV and LRI-II. The craft were operated at craft speeds of 6, 10, 12, 15, 20, 25, 30 and 35 knots and maximum speed. These speeds were chosen to coincide with pre-defined rough-water full-scale and model-scale test craft speeds and to provide sufficient data points to define the speed-trim curves. The results presented are the average of two measurements taken on reciprocal runs, which were conducted to minimize the effects of wind, waves, and current. Craft speed was measured using a Garmin model GPS 18 5Hz Wide Area Augmentation System (WAAS) GPS receiver. GPS data was acquired at a rate of five times per second.

Running trim, referenced to the craft’s keel, was measured using a MicroStrain model

3DM-GX3-45 inertial measurement system. Engine speed, percent load, and fuel consumption data was gathered from the J1939 CAN data broadcast to the onboard system on the boat.

Craft speed, running trim, engine speed, engine load, and fuel consumption were recorded on a National Instruments CompactRIO (cRIO) real-time data acquisition system. This system provides for mixed-signal stand-alone data acquisition, allowing the measurement and storage of analog and digital data at a rate of 2000 samples per second, and mixed-rate serial data. Analog data has 24-bit resolution and is hardware low-pass filtered to prevent signal aliasing. Figure 12 shows the data acquisition system. NSWCCD DN Test and Evaluation personnel operated the data collection equipment.

Calm-Water Test Range

Figure 12. National Instruments CompactRIO Data Acquisition System

Seakeeping

Seakeeping measurements were performed to document the motions and seakeeping characteristics of the craft when operated at various headings in a seaway. Measurements were acquired as the craft was operated in five directions relative to the prevailing sea to determine the effect of sea direction on overall acceleration and rotation magnitudes. Data was recorded at each aspect to the sea at a craft speed of 6, 12 and 25 knots or maximum safe speed for the sea conditions as determined by the craft’s USCG coxswain. Testing was performed in sea state 3 and 4 as defined by Table 2.

Testing was performed in the Atlantic Ocean off the coast of Virginia Beach, VA in the vicinity of NOAA National Data Buoy Center Station wavebuoy 44099 and anemometer CHLV2 as shown in Figure 13. Wavebuoy 44099 is a Datawell Waverider wavebuoy and its data is managed by Scripps Institution of Oceanography. It is located at 36°54'55" N 75°43'12" W and approximately 0.75 nm north of the anometer, CHLV2 which is atop Chesapeake Light Tower.

Measurements were acquired at five directions to the prevailing sea, representing head (0 degrees relative), bow (±45 degrees relative), beam (± 90 degrees relative), quarter (± 135 degrees relative), and stern (180 degrees relative) sea aspects. Because symmetrical response was assumed, data was not collected at each bow, beam, or quarter aspect. OTH-IV and LRI-II ran a star pattern, depicted in Figure 14, with the wave buoy in the center of the runs.

Figure 13. Rough Water Trials Location including NDBC 44099 and CHLV2

Figure 14. Seakeeping Star Pattern

Rough-Water Test Range

44099 CHLV2

Table 2. NATO Sea State Numerical Table for the Open Ocean North Atlantic

Sea State Significant Wave Height Range (ft)

Modal Period (sec)

Most Probable Period (sec)

2 0.3 – 1.6 3.3 – 12.8 7.5

3 1.6 – 4.1 5 – 14.8 7.5

4 4.1 – 8.2 6.1 – 15.2 8.6

5 8.2 – 13.1 8.3 – 15.5 9.7

Craft accelerations were measured at three locations on the craft as indicated in Figure 15 and Figure 16 using Silicon Designs model 2260-025 MEMS type accelerometers and recorded on a National Instruments cRIO data acquisition system. Vertical accelerometers were located at the bow and at the stern. Tri-axial accelerometers were installed at the LCG. All accelerometers had a range of ± 25 g full-scale with nominal 160 mV/g sensitivity. The accelerometers have a nominal frequency response of DC to 2000 Hz. Each accelerometer was independently calibrated, and individual sensitivity was used to convert measured voltage to acceleration.

Accelerations data was acquired at a digital sample rate of 2000 samples per second. This sample rate was chosen to minimize the potential effects of aliasing, optimize data file size, and accommodate the data analysis. Roll, pitch, and yaw rate data was also acquired using a

Microstrain 3DM-GX3-45 at a sample rate of 50 Hz.

Figure 15. OTH-IV Craft Motions Measurement Locations

Figure 16. LRI-II Craft Motions Measurement Locations

In addition to the accelerometer data, craft speed, position, course-over-ground, and time data were acquired five times a second using a Garmin model GPS 18 5Hz Wide Area

Augmentation System (WAAS) GPS receiver.

Craft motions data were recorded from the onboard data acquisition system in a National

Instruments defined Technical Data Management Streaming (TDMS) file format. TDMS file formats ensure an efficient storage means of scalable technical data. Binary TDMS files with associative header documentation were created with each acquisition. Data records were archived in TDMS format and converted for processing, reduction, and analysis. Files and associated data were also converted to text files for reading into a variety of software applications including Notepad and Microsoft Excel.

Craft motions data was analyzed using National Instruments LabVIEW software written by

NSWCCD DN. The custom analysis software allows for the importing, display, and analysis of craft motions data. Craft speed, accelerations, and angular rates were imported, and statistical quantities were then calculated for each of the data records. Average speed was determined by averaging all the data points for each test condition. Accelerations and angular rates were first demeaned, thus removing any zero offset prior to analysis. Root-mean-square (RMS) and root-mean-quad (RMQ) values were then calculated.

RMS values were calculated for each acceleration and angular rate (roll, pitch, and yaw) data record. The RMS, also known as the quadratic mean, is equivalent to the standard deviation for time varying signals with a zero average value. The RMS value provides a consistent baseline for comparing wave impact peak accelerations [3].

RMQ values have also been calculated and are included in the results for correlation with historical documents that tabulate RMQ values for use in human comfort and performance evaluations [4].

4 1 m m i ia

RMQ

In these equations ai are…