imposed in substituting heavier lead-acid batteries; how- 

 ever, it was regarded as worthwhile in view of the gain in 

 simplicity in supporting the system, in low cost, and in 

 ease of maintenance. The new battery system is the sub- 

 ject of a NEL report. 5 



A newer type lead-acid battery is now available which 

 will add 50 per cent more power with only a slight increase 

 in weight. These will be installed in the near future. 



2 0. UNDERWATER TELEPHONE 



The previous underwater telephone designed and built 

 by the Navy Electronics Laboratory, while an excellent unit, 

 was completely redesigned and rebuilt, resulting in improved 

 output power and reduced internal noise. In addition, the 

 unit was repackaged to fit the standard 19-inch rack mount 

 inside the sphere. Several new features were added which 

 make it more useful and efficient than in the past. 



21. SONAR 



A high resolution sonar unit designed and built by NEL 

 will be "chin" mounted on the bottomside of the bow of the 

 float. The pilot of the bathyscaph will be able to "see" up 

 to 150 feet in any direction while on the sea floor. With the 

 craft's increased maneuverability, the sonar unit is highly 

 desirable to prevent collision with obstructions on the sea 

 floor. 



22. GYRO DIRECTION SYSTEM 



Previously the bathyscaph had no directional reference 

 other than a magnetic compass, which was unsatisfactory 

 owing to magnetic disturbance inside the sphere. The 

 directional system used now is a converted aircraft-instru- 

 ment directional gyro. It is fitted with a separate, solid- 

 state 400- cycle ac power converter to provide the necessary 



See footnote reference 1, page 16 



43 



