Ocean Surveying from Manned Submersibles

Home , Aluminaut, Bathyscaphe, Submersible, The Diver, Trieste II (Bathyscaphe)

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 observations 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 submersible exceeds surface vessels. Any attempt at such a The past several years have witnessed the evolu- comparison wrold be mainly conjectural, as navigation 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 essentially 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 subsurface 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 bathyscaphes (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-

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TRANSPONDER NAVIGATION ( •••••••• T AfTER _55 ET.•••.•lHe I SURFACE ORIENTEO TRANSP STEM

UAnOOR SYNCRONlZEO PJHGER SYSTEM

FIgure 2. Operational and ProJXlsed Underwater Navigi!ttion Systems

Summer 2006 Volume 40, Number 2 19 ~ navigation also vary (Fig. 2). Owing to volume, power, before SINS can become an operational submersible and payload constraints of present vehicles, the major- system. ity of systems rely upon the support vessel to carry the bulk of instrumentation and perform the mechanics 2. Doppler Navigation Systems have been used oc- of plotting. Naturally, the accuracy of subsurface casionally on submersibles; the results of these tests, positioning is dependent upon the surface positioning unfortunately, have not been widely disseminated. Gen- systems, and these also vary. Following are examples eral indications are that this system is useful over a of the more promising and reliable systems now in smooth bottom but may yield poor results in areas of use; additional discussion of the acoustic and other high relief. problems related to use of the systems can be found in Mackenzie (1966) and in I.O.N. Proceedings (1966). 3. The Woods Hole Oceanographic Instituti on is de- veloping a system using 4 kHz synchronous pingers as Tracking Surface bottom beacons. A master clock on the submersible will be synchronized with the arrival time of pulses 1. A system in 'lse with the DSRV Alvin employs from three anchored pingers to obtain three ranges to a directional hydrophone and receiver on the support the vehicle. An advantage of this method is that there ship, and a 4 kHz and 20 kHz pinger on Alvin, the is no limit tothe number of surface or submerged ves- former with WWV to obtain slant range, the latter to sels which can use the system simultaneously. obtain bearing. The submersible's position relative to the surface ship is approximately ± 90 meters (300 ft.). 4. The U.s. Naval Oceanographic Office is devel- oping an acoustic transponder navigation system. On- 2. A second system employs an acoustic trans- board electronics will be used to square the ranges to ponder anchored on the sea floor and another trans- two transponders and take the difference of these ponder attached to the submersible. These two trans- squared ranges. This system will allow the submersi- ponders are interrogated alternately and received on ble to follow a series of parallel straight lines in order the ship by three hydrophones. The ship's position to completely cover a prescribed area. A somewhat relative to the anchored transponder then determines similar system using three transponders has been de- the submersible's position relative to the ship. Alter- veloped (Spiess et al, 1966) for positioning an unmanned nately. the bottom transponder can be replaced by an submersible at distances up to 14.6 kilometers (8 accurate surface positioning system when it is miles); with modification this system can be used for available. on-board DOSV positioning.

Oceanographic Sensors and Sensor Systems On Board-Tracking At this early stage of development there are no 1. A step beyond dead reckoning is obtained by standard instruments which can be transferred easily use of a compass and a device referred to as a "Uni- from vehicle to vehicle and, on the vehicles themselves, gator" (Busby & Hart, 1966). The Unigator consists there is no standardization in connectors or in mO"Jnt- of a weighted wheel suspended from the vehicle's ing arrangements. Hence, each instrument is tailor- keel on a freely rotating rod. An odometer is mounted made for each submt:l'sible, and in many cases, the externally and cable-connected to the wheel. The net techniques required to employ the instrument may result is a measurement of range when the submersi- result in degradation of its full data collecting capable traverses near-bottom; this can be coordinated city. Consequently, the present approach is to modify with an on-board compass to obtain bearing. instruments and tasks to accommo1ate the ssubmarines. However, due to the generally bottom topography, type of sediment and its bearing low speed of submersibles and the lack of space and capacity. depth to bedrock, acoustic parameters for payload available, further development is necessary communication and signal transmission, fouling and

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Summer 2006 Volume 40, Number 2 21 ~ boring organisms, water currents, visibility ranges, SURVEY MISSION PROFILES and water temperatures. Although the state-of -the-art is still deficient, The majority of the submersible sensor and support present efforts should soon provide the instrumenta- systems necessary to conduct surveys are available, tion needed to conduct a true undersea survey, and but are designed for application from a surface plat- at-sea application of these instruments will provide form. The instruments which are available and have the techniques necessary to effectively employ them. been employed from a submersible were, in few in- With navigation and instrumentation available, some stances, designed for submersible use. The need is for typical survey mission profiles are described. ease of application and the highest degree of automa- tic measuring and recording in order to free the surveyor for viewport observations. Site Surveys

From available positioning systems, possibly Transit satellite, the surface ship defines the boun- Surface Support daries of the area to be surveyed and marks each corner by dropping a recoverable transponder or The present method of transporting, launching! timed-pinger system. SeU-recordinginstruments may retrieving, tracking, and supporting submersibles is be incorporated into the markers to provide continuous from surface ships which vary from conventional hulls data over the tenure of the survey. Precise positioning to catamarans. Such support has performed marginally of the markers relative to each other can be ob- to well, but the outstanding deficiency is in launching tained by obtaining range and bearing on each marker and retrieving the submersible in anything greater from the submersible which can sequentially hover than a moderate sea. The advertised ability to launch adjacent to the markers and triangulate acoustically in 4 or greater sea states is misleading, for sea on the remaining three. state does not deal with wave period, which is the most controlling aspect of launch and retrieval. A With the navigation system installed, the survey short period (5-8 second) 2 or 3 meter sea, as often can be conducted in two phases (Fig. 4), phase one encountered in the North Atlantic Ocean, can abort a consisting of underway measurements such as side- projected dive; the same height wave of longer period scanning Sonar mapping and sub-bottom and gravity may not. The problem is one of winch and diver reac- or magnetic profiling. The salinity, temperature, tion time. Launching is no problem, but during re- sound-speed, and depth sensors can record and dis- trieval, when it is necessary for a diver to connect play during the entire submergence. The first phase lifting hooks to the vehicle and then lift withoot im- "flight" may be at an altitude between 60 and '15 parting abrupt, high tensional loads to the cable or meters (200-250 feet) to locate large scale topographic boom, is when the problem becomes severe. features. Level flight, necessary to interpret the data Present launch! retrieval systems concentrate on collected, may be controlled automatically by inte- booms (articulated or non-articulated) or catamarans grating submersible control devices with a depth! (Fig. 3). Although both systems are marginal, the altitude sensor. Additional vehicle attitude information non-articulated boom is least acceptable because of such as pitch, roll, yaw, etc., must also be recorded the pendulum effect. As long as the submersible is and monitored automatically. Position information can launched and retrieved from the surface, operators be read out and stored for track reconstruction and will always be weather restricted. This restriction be- also displayed on a track plotter during the flight comes virtually intolerable when operations in such for real-time course correction. All environmental vast ocean areas as the North Atlantic and North data may be stored on board the nOSY and also mon- Pacific can only be performed economically during itored as collected to ascertain anomalies that warrant 4 or 5 summer months. The advent of underwater study in greater detail. launch! retrieval systems not restricted by other than extreme weather conditions, will serve greatly toward Phase one data may be evaluated on the surface year-round economical submersible employment. ship to determine the most likely area for instrument implantment. Following selection of one or several of The surface ship also communicates by way of these areas, phase two may commence. Phase two underwater telephone with the submersible during discerns in fine detail the environmental properties the dive and plots the submerSible's course through bearing most heavily on design and installation of one of the methods discussed. In some instances the hardware. Such properties may be: sediment bearing receiving hydrophone is suspended from a dingy which strength, micro-topography, type of sediment, type and attempts to stay directly over the submersible while number of organisms, and past and present indications the larger ship lays off a mile or more. This is to or erosional processes. assure that the submersible does not surface under the larger ship on ascent. This procedure, in effect, The phase two survey area woold be smaller (per- testifies to the unreliability of today's tracking sys- haps 150 by 150 meters) and the coverage more de- tems. Reconstructing the submersible's position is tailed. In this mode, lane spacing would be governed further complicated by the fact that the dingy's posi- by range visibility, arbitrarily 10 meters (30 feet); tion must also be ascertained to find the submersi- hence, 20 meters (60 ft.) lane spacing would provide ble's position, as the larger ship carries the surface full visible coverage. The mission would consist of navigation equipment. alternately flying (5-6 meters altitude) and bottoming.

22 Marine Technology SocietyJournal ~ /

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IV // RANGE 3 ! !p------A. SUIlFACE SHIP PLANTS BOTTOM MARKERS TO OEFINE LIMITS B. OOSV TRILATERATES MARKERS TO FIX POSITION Of SUIlVEl AREA AND FOil SURFACE AND SUB- SURFACE RELAflVE TO EACIi MARKER. "AIIIGAr,ON. SHIP JHE" CONOUCTS BATH.METRIC RECONNAISS- ANCE.

MEASUREMENTS

SUB- SCAN SO"AR SUB-BOTTON PROF~E' MAG/jETIC ANOMALIES GRAVITY A/jOMALIES SAL IN'TY / TEMPERATURE

SOU/jO SPEED/OEPTH /BOTTOMEO MEASUREME/jTS

BOT TOM SAMPLE BEARING STRE •• GTIi SLOPE GRAOIE/jrS BIOLOGICAL SAMPLE I I RE OOX POTE/jT!AL o o CURRE/jTS I I PHOTOGRAPIiS I I I I U"OERwAy MEASUREME"TS 0 0 I I SlOE SCAN SONAR I o STEREO PHOTOGRAPIiY SUB - BOT TOM PROF I L E I I C'NE PIiOTOGRAPHY 0 0 o VISUAL OBSERVAT 10"S I I I I I I I I I 015M 0 0 I I I I I I

C. DOS V CO"DUCTS PHASE I SURVEY MAPS SALIEN T O. PHASE II SURVEY CONOUCTS IN SITU MEASUREMENTS FEATURES UNOERWAY AT 75 METERS ALTITUDE. AT BOTTOM STATION ANO OBTA, ••-..rGHER RESOLUTIO/j UNDERWAY MEASUREMENTS. AL TlTUOE 10 MET ERS.

Figure 4. Hypothonical Site Survey

Summer 2006 Volume 40, Number 2 23 ~ During the fiytng mission the DOSV would once again RCAlteSelection Surveys employ the sub-bottom prof tier for determining over- burden thickness to bedrock. Additionally, the Project- Design, method of implantment, and longevity of Scan-Record device (Briggs & Shipek, 1967) may, underwater cables and pipelines are governed, in large when developed, be employed to prOduce a rapid and part, by the nature of the bottom and dynamics of the accurate micro-topographic map. For the present, environment over and through which the equipment will micro-topographic mapping can be done with stereo- traverse. Although few reports have been written, photography (Pollio, 1968) which provides full photo- personal observations and discussions have revealed graphic coverage within a 6 meter wide lane. that extreme topographic rouglmess is the rule on the continental slope. Additionally, abrupt change in sedi- On the bottomed station, in situ strength or stability ment characteristics and current velocity are not measurements can be made and sediment or biological infrequent. samples collected. At any time during the survey, the nosv may divert its course to investigate, sample, or The DOSV can supply a comprehensive view of a photograph any bottom feature or organism. Benthic projected cable/pipeline routine which can be visually and pelagic populations can be identified and their observed and logged (documented) continuously by cine IUlmbers estimated or counted on calibrated photo- or stereo-photography; the sediment sampled at graphs. More significantly, continuous visual observa- selected intervals and the presence of potential boring tions can be made to provide a panorama of the entire or fouling organisms detected. Of particular impor- area. tance are visual observations which can provide an Indication of the dynamics of an environment by the The second phase completed, navigational markers textural characteristics of rocks or sediments present and sensors may be recalled by the support ship or along the projected course. the nos V. Prior to calling the markers the nosv may plant a long-life (two year or more) transponder in TrackIng during a route survey should be with a the center of the surveyed area to serve as a refer- mobile system and may be performed from the sur- ence point to aid in recovering the site at a later date. face with either of the two on board systems described Further oceanographic measurements which require previously or possibly with Doppler navigation. Sub- long-term observations for meaningful information, sequently, if inspection of the installed cable is de- could be ancillary sensors to the reference marker. sired the "unlgator" provides a simple and cheap method of measuring distance traversed. As noted, the limited dive duration does not economically allow DOSVtrans-Atlantic crossings to sur- "Bottom Truth" Survey vey a proposed rwte. The best survey application of submersibles is therefore in the shallower, rougher In this mode the DOSV may serve as a component ocean areas, but spot-checks can be made by the of the surface ship's surveying system and the sub- submersible at questionable points along the deeper mersible may be launched during or after the survey rCAlte. to spot-check questionable observations and inspect particularly variable topography, near-bottom currents or the like. On pre~selected locations along statistical representative or randomly selected tracks Biological Surveys the nosv may also be employed to verify or to provide detailed coverage. An example of the bottom truth Submarines and other manned devices have for survey was presented by R.F. Dill (1967) who dis- many years been applied to fishery research problems. covered 1 to 2 meter high outcrops which were com- To date, the most extensive Investigations have been pletely unnoticeable on fathograms obtained from Wide with the Russian converted "W" Class submarine angle (60 degree cone) transducers. These outcrops Severyanka; although limited to shallow depths, a were readily discernible on upslope traverses by wide variety of research has been conducted (Terry, Deepstar-4000. 1966).

The details of topography missed by wide angle One of the first correlations of oceanographic data echo sounder was vividly demonstrated during a recent and biologic observations was from the under-ice survey by the Naval Oceanographic Office with Alumi- voyage of the U.S. nuclear submarine Sea Dragon. The naut. The bottom contour chart in Figure SA was in- oceanographic-Instrumented submarine observed terpreted from sounding lines run at approximately plankton swarms while simultaneously collecting data 0.5 nautical mile spacing in the deep water area with on salinity, temperature, and depth. a 60 degree cone transducer. Subsequent to this opera- tion Aluminaut was employed to visually and photo- The U.S. Bureau of Commercial Fisheries recently graphically reconnoiter the bottom along line A-A' utilized the submersible Aluminaut to observe un- in Figure SA. The results of the reconnaissance are usually rich scallop beds off the Florida coast. Dredg- graphically presented in Figure 5B and amply demon- Ing the beds from the surface yielded unpredictable strate the inadequacies of wide angle cones for results of high catches, dead shells, or low catches. measuring the fine details of bottom topography. It is The submersible enabled biologists to make visual possible, however, that a narrow beam transducer or and photographic surveys of the scallop beds. From transducer towed near the bottom may reveal these these observations, it was discovered that the scallop features. bedS lay in "windrows" 30 to 90 meters (100-300 feet)

24 Marine Technology SocietyJournal ~ wide, accounting for the irregular results of the and enumerated. During the last observational period dredged hauls.(Taylor, 1968). a movie camera was used to record the organisms and large, bright scattering particles. One track of Fishery surveys conducted from submarines have Deepstar-4000 and the resultant observations are revealed significant advantages of direct underwater presented in Figure 6. Although surveying was not the observation. The fishery expeditions of the submarine primary aim of Dr. Barham's dives, this track Severyanka illustrated that by direct visual observa- serves as a partial example of what can be done in tion at various depths and conditions observers within the way of biological surveys with present equipment. the submarine were able to determine the migrations, population densities and distribution of herring schools, and to assess results of trawling techniques. Geological Surveying

Surveys and studies of the Deep Scattering Layer Using instruments and techniques previously de- (DSL) from manned submersibles have received parti- scribed, the geologist can selectively. rather than ran- cular attention in the past few years. Of particu- domly, sample outcrops or sediment and conduct lar significance are the DSL studies conducted by Dr. direct strike and dip measurements with accuracies Eric Barham of the U,S. Navy Electronics Laboratory comparable to terrestrial methods. Submersible in- (Barham & Davies, 1966). Although not strictly a strumentation presently used to sample well- surveying effort, Dr. Barham's diving procedures can consolidated outcrops is crude and requires a signi- serve as an example of the biological surveying ficant portion of the dive time; in contrast, however, techniques possible from a OOSV. to the seemingly pathetic practice of dragging a dredge across a suspected ootcrop several kilometers The basic operational plan was to first survey the below, it is an improvement of several orders magni- bioscattering patterns from the support ship with an tude, This ability to know that the sample comes from echo sounder; following which the submersible the undersea ootcrop and was not lying loose on the Deepstar-4000) was launched to conduct the in situ ocean floor is fundamental to constructing the geo- surveys. The dive was scheduled to investigate the logy and reconstructing the geologic history of an area. layer when it was either ascending or descending during which time DS-4000 made horizontal transects Sample collection to determine variability in sur- through the layer at various levels. Four observational face sediment size and areal distribution is particu- periods of 2 minute duration alternating with 2 minute larly suited to submersible investigations. Slope sta- dark periods were made during the 10 or 20 minutes bility measurements; the effect and distribution of of transit. During descent or ascent to the various marine borers and organisms, the chemical measure- levels, 1 or 2 minute "light looks" at 3 minute inter- ments within the sediment-water interface are phe- vals were performed while organisms were identified nomena particularly difficult to ascertain from the

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Figure 5. The Ocean Bonom as Oerl.OO from Echo Soundings (A) and Aug. ""'mod by Visual Observation IBI Along Line A·A'

Summer 2006 Volume 40, Number 2 25 ~ ~.. ~.•. i..

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surface but highly significant in assessing the present of the submersible's performance which reveal a small or potential dynamics of the bottom and near-bottom measure of its potential. environment. The submersible offers a platform from which a wide variety of sampling devices can be used; The most significant surveying advantage offered thereby bypassing the need for heavy, cumbersome from present submerSibles is the ability to determine surface sampling equipment which can introduce fine-grained topographic details which are wholly un- unknown and unmeasurable factors into the sample. obtainable from a remote surface platform. Over flat or gently rolling topography the resultant echogram is The potential use of manned submersibles to geo- a true one; that is, it represents the point-by-point logical surveying is widespread and highly significant. track of a ship. But over rugged topography the pro- Sensors and navigation systems required depend on file represents only the return to the transducer, what the surveyors wishes to accomplish and over especially so in the case of wide angle (60 degree) what areal extent. To date there have been few truly cones. An echogram of the bottom traversed by the geologi cal surveying dives, primarily because the in- support ship Lulu, while following Alvin, is shown in vestigator has been interested in studying only one Figure 7. The solid lines in this figure represent aspect of the bottom or sedimentary processes. One the topography as seen from Alvin which reported a of the more significant publications showing the value 200 meter (650 ft.) near-vertical cliff; the surface- of manned submersibles, as well as divers, to under- obtained echogram shows a gentle rise over the same sea geological mapping and studies can be found in area. True reconstruction of bottom topography is Shepard and Dill's (1967) comprehensive treatise on seriously handicapped in such areas if only surface- submarine canyons. obtained data is available.

Near-bottom currents have been observed to vary significantly with small lateral distances. The outcrop mosaic in Figure 8 was taken from Alvin in the Tongue AnVANTAGES OF SURVEYING FROM MANNED of the Ocean, Bahamas at 1280 meters (700fms.) depth. SUBMERSIBLES At the base of the outcrop ripple marks can be seen, while at the summit none are visible, although a sim- Although much of the manned submersible's poten- ilar finegrained sediment is present. Obviously, a dif- tial has yet to be realized, many occasions have ferent current condition existed at the base of this out- arised which demonstrate the present advantage it crop than at the summit although a lateral distance of offers to the ocean surveyor. Eventually, with long- only 2 meters separates the two areas. The signifi- duration submersibles, the most significant factor cance of this situation becomes apparent when one in- bearing on ocean operations, weather, can be ignored stalls a current meter from the surface to measure as an operational constraint. Following are examples near-bottom currents. A difference in horizontal posi-

26 Marine Technology SocietyJournal ~ F;~8. Flgure 9,

lioning of only several meters can mean the difference sediment cores collected from ships and tests per- between readings showing a significant current or formed in the laboratory, were calculated for clumps essentially no current. This was not an isolated in- of variws weights and dimensions. These clumps were stance, as almost every outcrop of this nature was dropped from the surface and their depth of penetration swept by currents not always present in the essentially observed from Alvin in water depths of 1036 meters featureless bottom surrounding such areas. On anup- (556 fms.). The calculated penetration was predicted slope, near-bottom transit from 1220 meters depth at 7 to 10 centimeters, while the observed penetration (666 fIDS.) in the florida Straits, Deepstar-4000 ran in situ was 18 to 48 centimeters. Other evidence in- normal to zones several hundred meters wide which dicating that laboratory testing versus in situ shear alternated from current speeds in excess of 25 cm/ sec strength measurements requires further investigation (0.5 kns.) to virtually no current. A true model of is discussed in Buffington et al (1967). Clearly, pre- bottom currents from surface-installed meters would dicting in situ bearing strengths from sediment cores be extremely difficult to obtain in this area if several which are disturbed to an unknown degree during sam- meters were not installed and planted within the dis- pling, exposed to entirely dissimilar environmental similar current zones. conditions and further disturbed during transportation is fraught with problems to which selective in situ Changes in bottom sediments can be abrupt, and measurements may provide the solution. remote sampling may result in erroneous interpreta- tions. The upper marginal escarpment of the Bahama Not only does the submersible allow measurements Banks is composed primarily of a hard, near-verti- in the actual environment, but much of the data can be cal limestone wall. This wall is cut by many terraces, available almost immediately through direct interior ledges and other irregularities which allow local ac- read-out. The delay between data collection and the cumulation of unconsolidated sediment (Figure 9) into final report is generally measured in months' but with which the surface sampler may fall, resulting in in- in situ measurements from a nosv this delay can be correct inferences as to its composition. Likewise, reduced to minutes. Consider, for example, the mea- an ecbo sounding profile of this wall shows the face to surements of near-bottom currents where it is re- be smooth and even; this is not the case and the oppor- quired to install the meter, collect the data retrieve tunity of iDStalling sensing devices between the 15 to the meter, develop the recording film. read the film 200 meter depth range would be ruled out on the basis and finally obtain the data. By direct read-out of cur- of surface-obtained data. rent velocity within a bottomed nOSY, data can be obtained in minutes; if more than a preliminary check Enhanced accuracy of measurements from sub- is required the submersible can plant selfrecording mersibles was indicated by the tests on dynamic load- meters for longer measurements with the added ad- ing of sediments from Alvin in the Bah.amas (Rucker vantage of knowing precisely the surrounding topo- et al, 1967). Dynamic penetration depths, based on graphy which may influence current now.

Summer 2006 Volume 40, Number 2 27 ~ ROSWELL F. BUSBY, B.S. Goology. 1958, The U.s. Navy has under construction a small American Uni\lBnity, M.S. Oceanography nuclear powered submersible. Successful performance 1960 Tens A & M Un/venity. HIS been of this vehicle will provide a long duration, virtually with the U.S. NIMII Oce ••.•ographic Office unlimited power, high payload submersible capable of .ince 1960 wIlere tie i.presently the Head of thu Deep Vahicisl B,•.. ch. He hal dived in operating independent of surface conditions and thereby and condUc1.ed operations with the submers.- abolishing the weather dependence inherent with sur- Ible. ALVIN, DEEPSTAR·4QOO. PERRY face-supported submersibles. Westinghouse Electric CUBMARINE, DEEP DIVER. AlUMI· Corporation envisions a Toroidal Support System (TSS) NAUT end STAR III end hold. Navy quellfi- consisting of a large mother submersible carrying one celion. for ISouba) diving. or several smaller, deeper-diving submersibles. In- corporated into the TSS is the capability of diver lockout/lock-in now available in the Perry-Link Deep Diver (Figure 2). The combination of diver/submersible is irresistible for work 00 the continental shelf, as it offers the power, speed and payload of the submersible with the dexterity and mobility of the diver.

Further extension of the submersible's surveying range may be provided by incorporation of unmanned Most oceanographic sampling is done on a statis- robot vehicles which can survey concurrently Withthe tical basis with observations made point-to-point at DOSV. Pairs of these vehicles may cruise alongside separations of several miles; this is followed by ex- the DOSV which can control tbeir movements, and trapolation of data between sampling points. The area simultaneous photography, side scanning sonar or sub- investigated is then treated as if continuously sampled. bottom profiling could be accomplished thereby pro- This classical procedure can lead to quite erroneous viding wider lane coverage in less time. Rebikoff (1967) conclusions; for example, including the work of Athearn has shown the practicality of such robots Witb his (1962) and Busby (1962), thousands of photographs of Poodle concept. the Tongue of the Ocean. Bahamas were taken to assess the nature of the bottom; only one outcrop was photo- Sensors and support instrumentation needed to con- graphed during these exposures. Subsequently, using duct and control submersible operations are receiving the submersible Alvin to reconnoiter the same area, considerable attention through development ofvarious numerous outcrops were observed on almost every U.S. Navy projects related to undersea search, salvage, dive (BUSby& Merrifield, 1967). Obviously, the point- and rescue efforts. When developed, these instruments to-point random sampling method managed in almost and support systems will be directly applicable to every case to photograph the intervening areas of un- ocean surveying and other undersea missions. consolidated sediment. The submersible, by allowing With the evolution of a truly long range and long continuous coverage between these points, provided a duration manned submersible, exploratory surveying true and significantly different picture of the bottom. missions of the "LeWis and Clark" variety Willbe not The preceding observations are but a few examples only possible, but also practical. Surely, the benefit of the advantages offered by manned submersibles to of allowing man direct visual observation and sampling the ocean surveyor; with future improvements, even of 70 percent of this planet's surface is equal to that more meaningful examples will accumulate. It mustbe of providing him the same privilege on the moon. noted however, that the picture is not all glowing; disadvantages are also present. High cost, limited power, payload and duration, low speed, discomfort, limited viewports, lack of sensors and navigational systems, launch/retrieval problems and almost routine break- down of various system components place the submersible at a distinct economic and operational disad- REFERENCES vantage with the surface vessel. Probably the greatest obstacle to eliminating many of these disadvantages 1. Arnold, H.A. 1967 Manned submersibles for research. is the high cost of operating or leasing a submersible; Science, vol. 158. No. 3799, p. 94-95. this in turn produces limited utilization by the surveying and scientific community, who, if able to directly 2. Barham, E.G. 1963 The deep scattering layer as obf:erv- experience the submersible's potential, would soon ed from bathyscaphe Trieste. Proc. XVI, Inter. Colig. demand development of more reliable and sophisticated Zoo!. vol. 4. instrumentation and vehicles. Perhaps the answer may be as suggested by Arnold (1967), in limited-term gov- 3. ---, and Davies, L£.1966 Bio-AcoWltics, U.S. Navy El",c. ernment support to make scientists in many fields Lab. Deep Submergence Log No. I, p. 31-38. aware of the capabilities and possibilities of these vehicles, 4. Breaker, L.A. and Winokur, R.S. 1968 The variahilityof bottom reflected signals using the deep research vehicle FUTURE CONCEPTS Alvin. U.S. Naval Oceanog. Off, 1.R. No. 67-92,22 pp.

Many of the present operational and instrumenta- 5, Briggs, R.O. and $hipek, C. 1967 Development of a new tion problems now connected with manned submersi- inst.rument for measuring ocean bottom micro-profile bles are being solved through a variety of efforts. relief. Trans. 3rt! Ann. Mar. Tech. Soc., p. 61-72.

28 Marine Technology SocietyJournal ~ 6. Brown, C.L. 1967 The use of multiple plankton sampling 23. Mackenzie, K.V. 1961 Sound 8peed measurements utiliz- nets on deep research vehicles. U.S. Navy Underwater ing the bathyscaphe T~ Jour. Acous. Soc. Amer., Sound Lab. Tech. Memo. No. 2213-58-67. vol. 33, p. 1113-1119.

7. Buffington, E.C., E.L. Hamilton, and Moore, D.C. 1967 24. ---, 1966 Position determination under the sea. Trans. Direct measurements of bottom slope, sediment sound 2nd Mar. Tech. Soc. Conf. & Exhibit, Exploiting the velocity and attenuation, and sediment shear strength Ocean, p. 147-157. from Deepstar-4000. 4th U.S. Navy Sym. on MJlItary Oceanog., vol. I, p. 81-90. 25. Marquet, W.M., Webb D.C., and Falrhurst, K.D. 1968 A recoverable deep ocean navigational beacon. Proc. 4th 8. Busby, R.F. 1967 Undersea penetration by ambient light Natl. I.S.A. Mar. Sci. Instru. Sym. (in print). and visibility. Science, vol. 58, No. 3805, p. 1178-1179. 26. Merrifield, R. and Delort, R.R. 1968 Results with U.S. 9. ---, Bright, C.V., and Pruna, A. 1965 Ocean bottom re- Naval Oceanographic Office deep research vehicle tran- connal.ssance off the east coast of Andros Island, Baha- sponder navigation system. Proc. 4th Nat!. I.S.A. Mar. mas, U.S. Naval Oceanog. Off. Teoh. Report No. 189, Sci. Instru. Sym. (in print). 59 pp. 27. Moore, D.G. 1963 Geological observations from the 10. ---, and Hart, W.E. 1966 Seafloor navigation for deep bathyscaphe Trieste near the edge of the continental submergence vehicles. Jour. Inst. Nav., vol. 13, No.2, shelf off San Diego, Calif. Geol. Soc. Amer. Bull., vol. p. 141-145. 74, p. 1957-1962.

11. ---, and Merrifield, R. 1967 Undersea studies with the 28. ---, 1965 Erosional channel wall in LaJolla Sea Fan DSRV Alvin, Tongue of the Ocean, Bahamas, U.S. Naval Valley from bathyscaph Trieste n. Geol. Soc. Arner. Oceanog. Off. I.R. No. 67-51, 54 pp. Bull., vol. 76, p. 385-391.

12. Dietz, R.S. 1968 Deepsea research in bathyscaph 29. Pollio, J. 1968 Sterer-photographic magging from sub- Trieste. The New Scientist, vol. 3, No. 74, p. 30-32. mersibles. Proc. S.P .I.E. Underwater Photo-Optlcal Inst. Applications Seminar (in pross). 13. Dill, R.F. 1967 Military significance of deeply submerged sea cliffs and rocky terraces on the continental slope. 30. Rebikoff, 0.1. 1967 The case for unmanned underwater 4th U.S. Navy Sym. on Military Oceanog., vol. 1, p. 106- systems. Sea Frontiers, vol. 12, No.3, p. 130-136. 120. 31. Richards, A.F. 1961 Investigation of deep sea sediment 14. Gershonovich, D.E. 1960 Observations on bottom depos- cores. Pt. I, U.S. Naval Oceanog. Office Tech. Rept. No. its made during voyages of Severyanka. Dept. Agr. Fish. 63, 69 pp. for Scotland. Marine Lab. Aberdeen Trans. No. 719. 15. Grice, G.D. 1962 Copepoda collected by the nuclear sub- 32. Rucker, J.B., Stiles, N.T. and Busby,R.F. 1967 Sea-floor marine Sea Dragon on a Crulse to and from the Nortb strength observations from the DSRVAlvin In the Tongue Pole with remarks on their geographic distribution. Jour. of the Ocean, Bahamas. Southeastern Geology, vol. 8, Mar. Res. vol. 20, No. I, p. 97-109. No. I, p. 1-8.

16. Hamilton, E.L. 1963 Sediment sound velocity measure- 33. Shepard, F.N. and DiU,R.F. 1967 SUbmarine Canyons and ments made In situ from bathyscaphe Trieste. Jour. Geo. Other Sea Valleys. Rand McNally and Co., Chicago, Res., vol. 68, p. 5991-5998. 367 pp.

17. Higgs, R.H. and Carroll, J.C. 1967 Aluminaut magneto- 34. Spiess, R.N., Loughridge, M.S. McGhee, M.S. and meter operations St. Croix, Virgin Islands 1966. U.S. Boegman, D.E. 1966 An acoustic transponder system. Naval Oceanog. Off. I.R. No. 67-33, 28 pp. Jour. Inst. Nav., vol. 13, No.3, p. 154-161.

18. Institute of Navigation Proceedings 1966 National Marine 35. Tamura, T. and Inone, N.19540bservationofthe amount Navigation Meeting, Manned Deep Submergence Vehicles. of star fish by Kuroshio, the undersea observation cham- ber. Monthly Report Hokkaido Region Fish Lab., vol. 11, 19. Interagency Committee on Oceanography 1965 Undersea No.9. Vehicles for Oceanography, Pamphlet No. 18. U.S. Govt. Printing Office. Washlngton, 81 pp. 36. Taylor, D.M. 1967 Billion dollar scallop find? Ocean in- dustry, vol. 2, No. 12, p. 20-24. 20. Jerlou, N.G. and Plccard J. 1958 Bathyscaphe measurement of daylight penetration Into the Mediterranean. Deep 37. Terry, R.D. 1966 The Deep Submersible. Western Peri- Sea Res., vol. 5 pp. 201-204. odicals, North Hollywood, Calif.

21. LaFond, E.C. 1962 Deep current measurements with the 38. U.S. Navy Electronics Laboratory 1966 NEL Deep SUb- bathyscaphe Trieste, Deep Sea Res., vol. 9, p. 115-116. mergence Log. Nos. I, 2, & 3.

22. Lomask, M. and Frassetto, R. 1960 Acoustic measure- 39. U.S. Navy Underwater Sound Laboratory 1966 Acoustic ments in deep water using the bathyscaphe. Jour. Acoustic research studies with deep submergence vehicies. Tech. Soc. Amer. vol. 32, No.8, p. 1028-1033. Memo No. 2211-06-66.

Summer 2006 Volume 40, Number 2 29 ~