Radio allowed communication between whale catchers and the factory ships or shore whaling stations. Catchers would report their catch and position four times a day so preparations could be made for their return with the catch. The downside to this was that competitors were also able to find out what a ship had caught, and where they had caught it. After WWII, radar was introduced to whaling. This allowed detection of other ships and icebergs up to 10 miles away, meaning that catchers could go out even in heavy fog.
The other use of radar was in finding “flagged” whales. These were whales which had been caught, killed and then set adrift, allowing the catcher to continue hunting. The shot whale was inflated with compressed air, so that it floated, and attached to a radio beacon, radar reflector and light. A company flag identified whom the whale belonged to. Whales were left floating this way until a catching shift was over, then collected and towed back to the whaling station.