Q&A: Time Signals for Sextant

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Question: Do you still do sights with a sextant? If so, where do you get the time signal from when underway? I found several shortwave frequencies for time signals on the web but the reception is extremely poor. In fact, I can’t get any useful exact time at all with my SSB receiver (Lowe HF-150 from the UK, built 1995), which otherwise works properly. I am sailing in the Med and I am a beginner with the sextant. Maybe you have some proven frequencies you could share with me?

Answer: I have to confess that I have hardly used my sextant in recent years except for using it to measure the height of an ice berg. However, I always used to set my watch before each ocean crossing by listening to WWV, the time signal out of Colorado in the USA, which is broadcast on 2.5, 5, 10, 15 and 20mhz. These are huge transmitters and I can almost always pull one of them in on our Icom SSB. In fact, I use WWV to check that our receiver is working OK.

You may have to try different times of day to find a time and frequency combination that will give you a clear signal in the Med. If you have no luck getting WWV with any time and frequency combination I would suspect a problem with your radio or its installation. Radio problems can be difficult to analyze, as we found out when we had a problem with tuning on our old SSB that only showed up at frequencies above 10mhz. The radio worked, but receiver sensitivity was poor at the higher frequencies.

I say that “I used to use WWV” because now I tend to just set my watch off the clock on our GPS, which is synchronized with the GPS system atomic clock and is deadly accurate.

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Peter Dunbar

I sailed across the Atlantic using sextant navigation a couple of years ago and used the “Timestamp” app on my iPhone to time sights. Apparently it sets to a reference signal whenever it gets internet access. Obviously no cell signal between the Falklands and Cape Town but for three weeks my sights and times were OK. The ability of the app to easily record multiple exact timestamps really made it easier to take sights.