to do something about it, and he became 

 interested in tools for cutting, grasping or 

 repairing. The result was a wide variety of 

 specialized instruments for particular sub- 

 mersibles; some worked well, others not at 

 all. 



Only in very few instances was the owner 

 or operator of a submersible its primary 

 user. In the commercial field the vehicle was 

 equipped to perform the basic functions of 

 safe diving and viewing, and the owner an- 

 ticipated that, for the most part, the user 

 (lessee) would supply his own equipment for 

 special tasks. Where the owner was the user, 

 e.g., International Hydrodynamics, the sub- 

 mersible was equipped with instrumentation 

 the owner/user felt was necessary to perform 

 the advertised services. In general, this lat- 

 ter requirement, in addition to equipment 

 required by the pilot to assure safe opera- 

 tions, included lights for viewing and photog- 

 raphy, cameras, depth gages, echo sounders 

 and manipulators. Essentially, the scientist 

 or engineer hailed an underwater taxi. If 

 much more than safe transportation was de- 

 sired, he had to supply the additional capa- 

 bilities himself. 



In the early 1960's, the submersible diver 

 had very few instruments from which to 

 choose: Underwater lights, cameras and 

 depth gages were available from over-the- 

 side systems. Echo sounders were numerous, 

 but the transducers were those convention- 

 ally mounted on surface ship hulls only a few 

 feet below the surface, and the great pres- 

 sures exerted on these externally-mounted 

 devices could affect their beam pattern and, 

 hence, the accuracy of the data. Water tem- 

 peratures could be measured by adapting 

 over-the-side instruments, as could sound ve- 

 locity and current velocity. The last could be 

 used only when the vehicle was bottomed. 

 Some bottom sampling capability existed, 

 but only in the form of 1- to 2-foot-long cores 

 of soft sediments or small, loose fragments 

 that could be scraped or picked from the 

 bottom. In some instances it was possible to 

 obtain measurements from instruments 

 within the pressure hull. Cosmic ray pene- 

 tration was measured in this manner from 

 TRIESTE prior to its record dive. But, for 

 the most part, the user of submersibles was 

 forced to either improvise his own instru- 



ment or modify existing ones to particular 

 tasks and submersibles. 



Manufacturers of oceanographic equip- 

 ment were interested in this potentially bur- 

 geoning market, but several factors caused 

 them to proceed with caution. Predominant 

 among these was the lack of a clearly defined 

 need to produce an instrument or instru- 

 ments which would find a wide market (2). 

 One-of-a-kind instruments are expensive to 

 design and produce and are not always prof- 

 itable when they must be made to perform 

 under the high pressure, low temperature 

 deep ocean environment. In the event an 

 instrument was successful, what would be 

 the size of the market? In the incipient sub- 

 mersible industry there were no clearly de- 

 fined missions where a specific instrument 

 could be expected to find application on ev- 

 ery dive and every vehicle. Private industry 

 was understandably hesitant to invest its 

 own funds and time developing instruments 

 for which there might be no market. Indeed, 

 considering the wide variety in submersible 

 characteristics, an instrument designed to 

 work on one might not be adaptable to any 

 other. Consequently, the scientist and engi- 

 neer was left mainly to his own devices in 

 developing instruments and work tools. 



CONSTRAINTS ON 

 SUBMERSIBLE 

 INSTRUMENTS 



The utility of an instrument or work tool 

 from a submersible is governed by 1) dimen- 

 sional and performance constraints (includ- 

 ing weight & balance) of the submersible 

 itself, 2) the overall submersible system and 

 its method of operation and 3) safety consid- 

 erations to passengers, support personnel 

 and the vehicle. 



Most scientific instruments consist of a 

 sensor and a recorder— the former located 

 outside the pressure hull and the latter in- 

 side. Both the seawater environment and the 

 submersible's internal environment apply a 

 peculiar set of operating conditions. Assum- 

 ing the vehicle's payload can accommodate 

 the instrument, the following are the major 

 constraints one must deal with to employ an 

 instrument safely and successfully. 



538 



