OCEAN SURVEYING FROM MANNED SUBMERSIBLES Roswell F. Busby "'rtiSl" sketch 01 the proposed Westinghouse Oeepstar 20,000. Deep Vehicles Branch U.s. Naval Oceanographic Of.fice ABSTRACT The performance of the bathyscaphes and second generation manned submersibles has generated considerable speculation concerning the merits of these platforms as undersea surveying teols. Although a wide variety of tasks have been successfully performed, the manned submersible is still too new ,a tool te have firmly established its role in oceanographic/engineering surveys. Undersea navigation, launch/retrieval methods and surveying sensors designed for submersible use are, in the main, unsatis- factory, but their development is being pursued. Prelim.inary observations indicate that the following surveying missions could benefit most highly through employment of a Deep Ocean Survey Vehicle, (DOSV): (1) Site Surveys of small ocean bottom areas for installation of hardware or habitats; (2) Bottom Truth Surveys of representative areas for verification of surface-obtained data; (3) Route Selection Surveys of prospective cable or pipeline routes; (4) Biological Surveys for quantitative and qualitative assessment of marine biota; and (5) Geological Surveys of hottom sediments, structures and depositional/erosional processes. Although little, if any, ocean surveying per se has been performed from submersibles, sufficient observa- tions exist te indicate tbat surface-conducted surveying may produce an erroneous impression of the bottom and near-bottom environment. Wide beam (60' cone) ecbo-sounding in tbe Bahamas completely missed 3 te 150 meter (l0-500 ft,) higb near-vertical cliffs and outcrops which have been observed from submersibles. Near-bottom current speeds have been observed to vary from essentially zero to 20 cm/sec (0.5 kos.) within a lateral distance of less than 1 meter. Zonation of currents along the bottom was observed in tbe Stralts of Florida which would have been virtually impoSSible to observe and interpret witb conventional measuring techniques. Abrupt changes in bottom sediment grain sizes have been observed which would lead to erroneous impressions if sampled from the surface. Preliminary tests have indicated that sediment bearing strengths measured from surface-collected cores may be in error by several orders of magnitude from measurements taken by manned submersibles in situ, INTRODUCTION conclusively in which surveying aspects the submer- sible exceeds surface vessels. Any attempt at such a The past several years have witnessed the evolu- comparison wrold be mainly conjectural, as naviga- tion of a new oceanographic platform: the manned tion, sensors. and techniques must be developed to submersible. The birth of" this revolutionary vehicle operate at the submerSible's full potential. Sufficient has been attended with conjecture and speculation work has been conducted to indicate that surveying concerning the advantages and disadvantages of per- from submersibles offers advantages which cannot forming oceanographic research and surveying under , be ignored and may indeed provide results which will rather than on, the ocean surface. The point has yet re-orient ror entire concept of ocean surveying as to be reached, however, where one can demonstrate well as ror concept of the marine environment. 16 Marine Technology SocietyJournal ~ TRIESTE II CUBMARINE PC3-B U.S. NAVY PERRY SUBMARINE BUilDERS. INC. length-76 Ft. Crew-3 length-23 Ft. Crew-2 Beam-IS FI. Speed-2 Kn. Crui.e Beom-3.5 Ft. Speed-l.S Kn. Crulle Height 18 Fl. Poylood-20.000 lb •. He,ght-6 Ft. Payload 7S0 lb •. Operating Deplh-20.000 Ft. Operating Depth 600 Ft. I DEEP DIVER-PL-4 DE EPSTAR-4000 OCEAN SYSTEMS INC. WESTINGHOUSE ElEC. CORP. length-23 Ft. Crew-2&2 Divers length-IS Fl. Crew-3 Beo.n-S.S Fl. Speed-2 Kn. Crui •• Beom-IO Fl. Speed-I Kn. Cru,.e Height-9 Ft. Poylood-2ooo lb •. Height-l FI. Poylood-4S0 lb,. Operating Deplh-13S0 Ft. (lockout 1250 F'-I Operohng Depth 4000 FI. ALVIN ALUMINAUT U.S. NAVY REYNOlDS INTERNATIONAL length-22 Fl. Crew-3 length-Sl FI. Crew-6 Beam-S,S Ft. Speed-1.5 Kn. Crui.e Beom-B Ft. Speed-2.S Kn. Crull. Height-13 Fl. Paylood-4S0 lb,. Height-141/4 Fr. Poylood-6000 lb •. Operating Depth 6000 Fl. Operating Depth 6000 FI. Summer 2006 Volume 40, Number 2 17 ~ CONVENTIONAL TECHNIQUES Operationally the bathyscaphes performed essen- tially as elevators with very limited lateral range, and required extensive support faciltttes for routine maintenance, towing to dive site, and periodic over- For the purpose of this discussion a survey will haul. Only rudimentary surveying was accomplished be defined as a mission to observe and/or measure owing to their limited excursion range and parti- one or several environmental properties to delineate cularly by the virtual lack of navigation and surveying their temporal and spatial variations. Such a mission instrumentation. may include in situ measurements and collection of samples. The platform used to conduct these surveys will be referred to as a nosv (Deep Oceanographic Survey Vehicle), a sell-powered a.nd sell-controllable Second Generation Submersibles undersea vehicle capable of carrying passengers in a dry habitat. The Thresher disaster in 1963 and the increased Conventional surveying instrumentation may be interest in in situ oceanographic observations and lowered, towed, or fixed devices employed from a measurements, encouraged production of many sub- surface platform either underway or drifting. Position- mersibles. The number of planned vehicles varies al- ing (navigation) is provided through a variety of means most monthly, however, at this writing there are 44 depending upon requirements and location. operational and planned submersibles throughout the world. Near-surface instrumentation employed underway provides large area coverage and fairly rapid accumu- The submersibles which followed the bathyscaphes lation of data. Towed instruments can be operated at (Fig. 1) provide greater submerged horizontal range, cruising speed in some instances, but at reduced better maneuverability, increased viewing capability, speeds in others. Much of the larger towed instru- decreased maintenance, and are primarily fail-safe mentation is weather-dependent and may be governed devices, in that the pressure-resistant compartment by ease of launch and retrieval. Lowered instruments carrying the passengers is positively buoyant. This may require the ship to drift or stay on station, and differs from the bathyscaphe pressure spheres which launching of the heavier devices during inclement would sink were it not for their gasoline-filled nota- tation compartments. The smaller size and reduced weather can be difficult j moreover, the instroments' submerged position relative to the ship is generally weight of the second generation submersibles also unknown. In some instances, such as bottom sediment offers greater mobility by allowing the vehicles to be coring, it is necessary to transport samples to a launched and retrieved from a surface support ship land-ba.sed laboratory for performance oftests requir- which can transport the submersible to distant dive ing a stable platform. Accumulation of survey data sites and haul it aboard at-sea for maintenance and through these means is an on-going project and more repair. A comprehensive discussion of the design and sophisticated and newer instrument packages are operational characteristics of American submersibles rapidly appearing. to 1965 can be found in I.C.O. Pamphlet No. 18 and an up-to-date listing in Arnold (1967). Individual studies and tasks performed by present submersibles vary with almost every dive. The high UNDERSEA SURVEYS cost of submersibles produces short-tenure leases which generally result in a new scientific passenger for each dive or short series of dives; the result of such programs has led to a variety of investiga- The Bathyscaphes tions which are listed in the Bibliography. A review of the literature reveals that little, if any, undersea Using essentially the same principles as the stra- surveying per se has been conducted. Instead, the tospheric balloon for negative and positive buoyancy, majority of dives have been research-oriented and the bathyscaphes (FRNS-2, FRNS-3, Trieste I) com- investigated specific phenomena or processes dis- pleted many deep, manned dives which culminated in covered during past studies from surface vessels. a 10,900 meter (35,800 ft.) descent by Trieste I in 1960 to the deepest known ocean depth. Over 128 dives were made by Trieste I until it was retired in 1964, 35 of these were for scientific purposes (ICO Pamphlet 18, 1965). Of the presently operating bathy- scaphes (Trieste n; Archimede) only Archimede is INSTRUMENTATION AND SUPPORT REQUlRE- directed primarily towards scientific studies. MENTS: STATE-OF-THE-ART The scientific and technical accomplishments of the bathyscaphes are many and varied; investigations into sound speed variations, gravity anomalies, biolo- Subsurface Navigation gical phenomena, ambient noise measurements and geological processes are but a small sampling of As would be expected in a field where no two the studies pursued. vehicles are similar, the approaches to subsurface 18 Marine Technology SocietyJournal ~ TIMED PH;£~ 20 •••.••••••. Sf"''''LOOR' SURFACE RANGE/BEARlNG TRACKING SYSTEM PRO.lECTOR- ACOUS T Ie TI!ANSPONll(R '"-- TRANSPONDER NAVIGATION ( •••••••• T AfTER _55 ET.•••.•lHe I SURFACE ORIENTEO TRANSP STEM UAnOOR SYNCRONlZEO PJHGER SYSTEM FIgure 2. Operational and ProJXlsed Underwater