745 
PE St 
shots two composite gauge blocks) was carefully lowered and then snubbed by 
the safety line from one of the composite gauge blocks or the recovery line 
running to the connection buoy. lLowering was continued and the various com- 
ponents cast off as they reached their final depth. The connection buoy 
(which also supported the lead weight) was then made ready to go overboard, 
and the lead weight lowered by means of the main towing cable which ran from 
the drum on the winch. As this gear dropped astern of the boat the piezo-— 
electric gauge lines which ran along the surface were payedout. Since the 
large reel holding these lines was on the starboard side of the boat amid- 
ships, these cables previously had been led around the stern of the boat and 
up the port side outside of <ll rigging to the bow (Fig. 5 and 31). They 
were then payed out until there was no slack to the drum; the cables were 
reeled off the drum as the gear dropped astern, A manila line to take the 
strain from the electrical cables was made fast to the connection barrels 
and was payed out with the electrical cables, At intervals of approximately 
60- ft a spherical surface buoy was attached connecting the electrical cables 
and the rope line together by means of a snap hook passing through grommets 
on these two lines, This gear was payed out as quickly as possible, syn- 
chronizing the rate for the electrical cables with the rate for the towing 
cable from the main drum (Fig. 32). When the charge was about 600 ft from 
the vessel it was in position for firing, With smaller size charges (less 
than 50 1b) it was net necessary to pay out the entire amount of cable be- 
fore firing the charge. 
After securing the main towing cable and the rope line taking the strain 
from the electrical cables, the patch cords were plugged in to the Miller 
connectors on the large reel. All patch cords were color coded for plugging 
into the big reel to minimize the possibility of error in connecting the 
proper gauge to the proper oscillograph recording channel. After the cali- 
bration of the electrical and recording eauipment was made the charge was 
fired from the electronics cabin. Coordination was necessary at all times 
betreen the electronics cabin and the master of the vessel to be sure that 
the water was of sufficient depth, and aiso that no traffic was near the 
point at which the charge was being fired. An intercommunication system was 
used for this purpose. 
(b) Retxieving the gear. -- (i) After firing the charge. When the 
charge was fifed the gear was cut into two halves, split at the position 
formerly occupied by the charge, The stern part of the gear drifted off 
with the tide, while the forward part of the gear was still attached by means 
of the tow line and the electrical surface line to the vessel, The main 
towing cable was reeled in on the winch drum in coordination with the elec— 
trical cables being brought in by pulling the manila strain line on a gypsy 
head. As the electrical cables were separated from the manila strain line 
they were reeled onto the large reel, where the patch cords had been pre- 
viously disconnected, This large reel was driven by an electric motor and 
a Graham adjustable speed transmission, (Power drive for this reel was 
necessary because of the great weight of the cables. Before power drive 
was installed it required two men to turn this reel by hand and one man to 
lead the cables onto the reel. After power drive was installed one man 
could control the reel and lead the cables onto it without additional help.) 
