NICHU-T-87 003 C3 Loi'!N !.r !PY O!,.l y DIQER EDUCATION SERIES Tethered Scuba Diu»g l.ee H. Soakers Michigan Sea Grant College Program MiCHU-SG-87-503 DIVER EDUCATION SERiES Tethered Scuba Diving lee H. Somers Michigan Sea Grant Coilege Program MICHU-SG-87-503 Nichigan Sea Grant is a cooperative program of The University of Nichigan and Nichigan State University. It is part of a national network of Sea Grant programs of fering marine and Great Lakes research, education> and extension services. In addition to diving and water safety programs< Michigan Sea Grant conducts research' produces publications, and provides extension assistance on shoreline erosion> waterfront development, commercial and sport fisheries> toxic substances> and marine transportation and engineering. Contact the address on the last page for a publications catalog or other information. Lee 8. Soeers is an Associate Research Scientist+ Department of Atmospheric and Oceanic Science; Assistant Professor, Division of Physical Education; and Diving Safety Coordinator> Department of Occupational Safety and Environmental Healthy The University of Nichigan. He is also Nichigan Sea Grant's Ex tension Specialist in diver education< diving technology< and aquatic accident management. Dr. Somers' 30-year diving career has included commercial< research, search and rescue~ saturation, polar, cave and ocean diving, and directorship of a hyperbaric chamber facility. He holds recreational diving instructor certifications from the National Association of Underwater Instructors and Professional Association of Diving Instructors. This publication is the result of work sponsored by the Michigan Sea Grant College Program with grant NA85AA-D-SG045 from the National Sea Grant College Program, National Oceanic and Atmospheric Administration NOAA! r U.S. Department of Commercer and funds from the State of Michigan. Price $2.25 TABLE OF CONTENTS I NTRODUCTION ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ e e ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ e ~ e e e ~ ~ e ~ ~ e e e ~ ~ ~ ~ P ERSONNEL ~ ~ ~ ~ ~ ~ se ~ ~ ~ ~ ~ ~ e ~ ~ ~ ~ ~ ~ ~ ~ e ~ ~ ~ ~ ~ ~ ~ eess ~ ~ ~ ~ ~ ~ ~ ~ es ~ ~ ~ ~ ~ Instructor of Tethered Scuba Diving Trainee Qualif ications Tender 45 45 Diving Supervisor Stand-by Diver Other Personnel 6 6 Dive Team E QUIPNENT s e s ~ s ~ ~ ~ ~ s s s ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ e e ~ e ~ ~ ~ ~ ~ e e e e e e s s ~ ~ ~ ~ e e e Nask ~ e ~ ~ ~ ~ ~ e ~ e ~ ~ ~ ~ ~ ~ ~ ~ ~ e ~ ~ ~ ~ ~ ~ ~ ~ ~ s ~ ~ ~ ~ ~ ~ ~ esses ~ ~ ~ ~ e ~ ~ ~ 7 T ether Commun1ca talons Un] t ~ ~ ~ s e ~ ~ ~ ~ ~ ~ ~ s ~ ~ ~ ~ ~ ~ ~ ~ ~ e 8 9 Emergency Self-Contained Air Supply Options 10 Safety Harness/Tether Attachment 12 Standard Scuba Equipment 12 TETHERED SCUBA DIVING PROCEDURES AND TECHNIQUES 12 Preliminary Dive Planning 13 Survey of Nission or Task 14 Evaluation of Environmental Conditions 14 Selection of Diving Techniques s ~ e ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 16 Selection of Divers/Support Personnel a nd Assignment of Task 18 Selection of Equipment 18 Fulfillment of Safety Precautions 18 Establish Procedures and Brief Personne 1 s ~ s ~ ~ ~ ~ ~ ~ e e e e ~ 19 Diving Vessels ... e ~~ ~~ ~~ ~~ ~~ ~ ' ~~ ~~ ~ 19 Assemble Equipment 21 Diver Dressing Procedures 21 The Delve ~ ~ ~ ~ ~ ~ ~ ~ ~ e ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ i ~ ~ ~ ~ ~ ~ 22 Tending the Diver 24 AsCent ~ e ~ ~ ~ ~ e ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 27 Post-Dive Procedures 27 UNDERWATER ENERGENCY PROCEDURES . ...... ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 29 Loss of Primary Air Supply 29 Flooded Full-Face Nask 31 Entanglement ~ s ~ ~ ~ ~ ~ e e e e e e ~ ~ ~ 32 Loss of Communications 33 S UNWARY ~ ~ ~ s e s s ~ ~ e ~ ~ ~ e e s ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ e e ~ ~ s ~ ~ ~ ~ e ~ ~ e ~ ~ ~ ~ ~ 33 REFERENCES APPENDIX I: Tethered Scuba Diving Training Program ....... 35 APPENDIX II: Estimating Diver Air Consumption & Available Ai r Supply ......................... 37 APPENDIX III: Tethered Scuba Diving Equipment List ......... 39 DIVER EDUCATION SERIES TETHERED SCUBA DIVING Lee H. Somers, PhD INTRODUCTION Swimming and working underwater using self-contained underwater breathing apparatus scuba! is a standard practice in military< scientific< and recreational diving. Accepted safety procedures for scuba diving operations generally require deployment of divers in pairs i.e., use of the buddy system!. On the other hand, commercial divers more commonly use surface- supplied or umbilical! di ving equipment and procedures. This mode of diving usually implies deployment of a single diver to accomplish the underwater task. The diver is supported by a tender on the surface or in a diving bell. A less commonly used mode of diving is tethered scuba diving. This generally involves the deployment of a single scuba diver who is tended from the surface by means of a safety line or tether. Safety and operational requirements for this mode of diving are addressed in the U. S. Navy Diving Nanual and in the U. S. Depar tment of Labor Occupational Heal th and Sa fety Administration! and U. S. Coast Guard requirements for commercial diving operations , 3, 43. Tethered scuba diving is probably one of the most under- rated and misunderstood of all diving modes. The procedures and equipment used for tethered scuba diving by some commercial divers are considered to be haphazard by many diving safety authorities. Search and rescue teams commonly use a single line tended mode of scuba diving Ll]. However, very few dive teams actual ly use the equipment and procedures that are described in this publication. Tradition, lack of state-of-the-art equipment, inadequate training, economic constraints> and narrowly-scoped recreational diving influences have compromised advancements and, in some respects, safety in search/rescue and scientific diving. Tethered diving has never been officially accepted by the recreational diving community in the United States. Furthermore, only a limited number of scientific divers currently use tethered scuba techniques, probably because most scientists have been trained by recreational diving instructors. Critics of tethered scuba diving include the following concerns: * Scuba diving without a buddy is unsafe; * The diver could be at high risk if the safety line or te ther became en tang 1 ed; * The diver would not have the assistance of a buddy in the event of air supply failure or depletion; and * The diver would surely drown in the event of loss of consciousness. On the other hand> advocates of tethered scuba diving consider the following factors in support of the practice: * Tethered scuba div ing may only be used for selected underwater activities< not as a complete substitute for all conventional scuba diving or surface-supplied diving; The tethered scuba diver is not diving alone since the surface tender, in realityr functions as a buddy; * modern diving practices include the use of voice communications between the diver and tender, thus providing a means of constantly monitoring the diver's status; Use of a single tethered scuba diver is probably a safer practice for diving in very limited visibility water than free swimming scuba diving where buddy separation is more probable and underwater emergency assistance requi rements such as sharing air are extremely dif ficult at best> if not impossib le; Loss of air supply or primary regulator malfunction emergencies can easily be resolved by using scuba fitted with dual regulators or a compact secondary scuba; and If a diver loses consciousness underwater, the full face mask would prevent immediate drowning and loss of communications/line response would prompt the tender to immediately recover the diver and/or deploy a stand-by diver. The equipment and procedures for present day tethered scuba diving presented in this publication are significantly different from those used in past years. Commonly< tethered scuba diving has implied attaching a rope to a solo diver using a conventional mouthpiece-style scuba regulator. There was no full-face mask security, no emergency air supply alternatives, no communications except line-pull signals!, and, generally, no specific training. The fol lowing conditions and limitations are recommended for modern te thered scuba di v ing opera t ions: Depthisgenerally limited to 60 ft. except in standby diver deployment emergency!; Communications/streng th member tether must be secured to the diver's scuba or safety harness; A full-face mask must be used; * An emergency or secondary air supply and/or regulator system must be used; and * The diver must surface when cylinder pressure is reduced to no less than 500 psi 00 psi for twin cylinder scuba!. Although tethered scuba diving is not considered as acceptable as surface-supplied diving by most researchers and commercial divers, it has proven satisfactory and safe for selected diving operations and stand-by diver application. It has been especially useful for very limited to zero visibility shallow water research where the dive team does not have a surface-supplied system available. Under such conditions the presence of a second diver is of little or no safety benefit and may even constitute additional risk. Tethered scuba diving has also been effectively used for extremely cold weather diving from smal 1, open boats where the deployment of two divers would have greatly complicated logistics and increased the surface exposure time. This mode has been successfully used for under ice diving. This publication has been prepared to serve as an inforaational document for individuals/groups who are considering the use of tethered scuba diving in scientific,