10 le-ihiioi 



It Is estimated that about 5 percent of 

 the systems deemed operational may be 

 considered marginal relative to their 

 level of readiness because of the addi- 

 tional time that would be required for 

 mobilization, crew training and prepared- 

 ness. Excluded from this review are wet 

 submersibles operated by divers and those 

 designed for operation in depths less than 

 600 feet (183 meters). Also excluded from 

 this survey are proposed vehicle designs 

 which may or may not be constructed. 

 However, some of the unique designs are 

 reviewed herein. The total of 155 compares 

 to 103 reported'^ one year ago. However, 

 when taking into account those vehicles 

 inadvertently overlooked in the first 

 world-wide survey, there is about a 32 

 percent increase in both categories; i.e., 

 manned and unmanned vehicles. 



The average characteristics of the world's 

 undersea vehicles are given in Table 3. In 

 averaging the figures, it was necessary to 

 exclude 3 or 4 systems such as the large 

 bathyscaphes to avoid skewing the statis- 

 tics of the more typical systems. 



Because of the continuous trend to go 

 deeper the average depth capability of the 

 world's manned submersibles has increased 

 from 2,250 feet reported one year ago to 

 2,450 feet, about a 10 percent increase. 



The average weight of manned vehicles has 

 increased from 19,000 lbs. a year ago to 

 24,000 lbs now, about a 26 percent 

 increase. This is due to several factors: 

 going deeper, increasing pay load and new 

 systems with diver lockout capability. 



There are now 15 vehicles with diver 

 lockout capability, about 15 percent of 

 the manned vehicles. 



The average payload capability was calcu- 

 lated to be 1,300 lbs. for manned vehicles 

 and a very low average value for the listed 

 unmanned systems, because most of the 

 unmanned systems are instrumented for a 

 specific mission, and do not provide 

 additional payload space. 



In comparing several manned and unmanned 

 systems with given payload capability, 

 there is about a 6 to 1 ratio of depth 

 capability versus weight in favor of 

 unmanned vehicle systems over manned 



systems. This is mainly due to the fact 

 that the manned system includes a crew 

 which in turn requires habitable space in 

 a pressure hull, life support; and extra 

 power, all of which adds weight and 

 requires compensating buoyancy, and even 

 more power to propel the larger wetted 

 surface system. However, if the given 

 mission requires the man in the system 

 for greater observation capability, better 

 mission control and adaptability, or for 

 diver lockout operations , than the fore- 

 going comparison applies only to certain 

 types of missions. 



For the manned vehicles, the average crew 

 size was 3 and the average life support 

 was calculated to be about 120 man-hours 

 or 40 hours per man. This figure is con- 

 sidered low and many believe that 72 

 hours per man should be the minimum 

 requirements for safety in the event of 

 disablement and need to await search and 

 rescue. However, in some missions that 

 require working in rougher waters, further 

 offshore and at greater depths, provisions 

 should include additional emergency life 

 support capability. 



Depending on the mission requirements, 

 there is need for both manned and unmanned 

 systems, and I believe this option will 

 always exist. There are many missions 

 involving hazardous operations; e.g., under 

 the ice packs, areas with potential 

 entanglement problems or operating near 

 radioactive or other hazardous materials, 

 and missions involving long duration area 

 search may better be performed by unmanned, 

 tethered systems. 



Though support ships are required with both 

 manned and unmanned systems, each has 

 peculiar requirements. Launch and retriev- 

 al of vehicles is still a problem. In 

 addition to cable handling and winching, 

 the unmanned system often requires that 

 the support ship have special maneuvering 

 and station keeping characteristics to 

 tend the tethered vehicle. The manned 

 system requires a heavier duty crane and 

 handling system. For any mission, selec- 

 tion of manned or unmanned systems depends 

 on the outcome of trade-off analysis 

 primarily assessing operating effectiveness 

 in meeting a given set of mission require- 

 ments versus cost. 



