The explosion, its range put at three miles by the Roosevelt’s sonar conversion computer, was heard aboard the sub as no more than a muffled cough, but it was loud enough to startle Robert Brentwood out of his light sleep, his photo of Rosemary sliding from his chest as his hand darted out to stop the Walkman from falling as he turned. Glancing up at the Control relay in his cabin, he saw the sub was maintaining the anticipated TACAMO rendezvous by crawling along at less than 3.5 knots on the emergency “bring it home” shaft against a crosscurrent. The current, surprisingly strong and not marked on the chart, was disconcertingly “mixed” in temperature and salinity.
As officer of the deck, Peter Zeldman lost no time in alerting everyone in Control to a possible inversion layer coming up. Soon every man aboard knew the sub might be approaching a “plume,” a less dense area of water caused by either fresh or hot water springs from the earth’s crust “streaming” through the colder, more dense sea around them. And everyone knew how many subs before them had suddenly plunged in a less dense column, hitting the bottom at over 130 miles an hour before tanks could be vented to regain neutral buoyancy.
The explosion, albeit muted in the distance, was at once an added strain and a possible relief for those in Control as it could mean that another Allied submarine was in the area, unknowingly taking the heat off them. On the other hand, as Zeldman pointed out to Brentwood, if it had been an enemy ASW aircraft or surface vessel searching for the Roosevelt, then the explosion some way off indicated that the sub’s pursuers were way off course and had merely been attacking blind, looking for the sub around the last reported position of the Yumashev.
But whatever was going on about him, Robert Brentwood was certain of one thing — after his sinking the cruiser, the Russians would gather their forces, and he, like the convoys, could expect more determined and pervasive attacks en route to the haven of Scotland’s Holy Loch, still over a thousand miles to the northeast. Brentwood also knew that now there was no way they could risk going up for a TACAMO rendezvous. They were on their own.