Obviously, the equipment was not in operation during their high speed run. So I suppose the sub thought they knew their location in relation to all the hazards in the area.
I remember reading that the Russians, during the Warsaw pact days, mapped out the Northern Atlantic valleys and sea mounts from the port of Murmansk doing 40 knot or more high speed runs. So they could break out into the Atlantic in time of war. The would not use sonar, they used time/speed plans to do it in the blind.
Russian subs in Tom Clancy's the "Hunt for Red October" used that method to transit to the mid-Atlantic.