RDF Story (for some).
We have a late 70's era Seafix RDF that kind of looks like a lunch-box on a pistol grip handle with a hand bearing compass
sitting on top and a pair of earphones that we thought was the penultimate “high technology” gear
when we got it. At one point, in the time before we had Radar and before we had fully embraced GPS
, we were fog-bound near the mouth of the northwest entry channel to our harbor. As there was an RDF transmitting station at the foot of the channel, one could limber up one's RDF and sail “down the beam”, into the harbor in a pea-soup fog
, ticking off channel marks as one passed each in turn. While hove too at the channel mouth, taking the first swing with the RDF, a small motor
cruiser passed us at dead slow, close abeam. We waved to the helmsman as he passed and were surprised when he suddenly slowed, reversed course and idled up to our windward rail. “Has there been some kind of accident
?” he questioned, “Is everything okay?” “Why yes, I think so” I responded “everything's good with us, why do you ask?” “Well” he answered “I saw you using that Gieger Counter thing and I was worried that there might have been a problem at Diablo Canyon I needed to know about, so I thought I’d better ask!” “Ah… Nope. Nobody glowing hereabouts that we know of” I responded. “Gee thanks” he sighed, “that's a relief”, and with that, sped of into the gloom. “Do you believe that?” I asked my tired, chilled, damp, (much) better half. “At this point I'd believe anything that would get us anchored and a bowel of hot soup. Get moving Buster!” And so we did, faithfully following the Null on our “Geiger Counter”.
And we still have the old girl today (the Geiger Counter that is). And, she still works.