Seafix D/F

[Appleyard]

Evening all.. I have discovered that my recently purchased boat has a Seafix direction finder included in its bits and pieces... I have not come across this type of kit before.. Can anyone tell me how it is used .and any other advice welcome

 

[Guest]

Keep it as a Museum piece ..... it's virtually useless around UK / Europe now as the Radio Nav beacons are turned of or not maintained anymore.

It used to be used for obtaining a bearing line from a radio beacon ... get 2 or more similar and cross them for a fix ... in fact you could mix RDF / Compass Brg / Radar brg etc. to get a fix .... BUT RDF was Great Circle and needed correcting.

FYI - I still have mine and it still works ... picks up stations but NOT RDF ones .... I'm keeping mine for nostalgia and as an Heirloom !!

 

[Appleyard]

Yeeeesssss...... I had a funny feeling that it was a bit of an antique. However it will be interesting to try it out and see if it works . Thanks

 

[FWB]

If you're going to use it as a living museum piece then you might find it useful to convert it to a PP9 battery. I did this to the one I had 20 odd years ago and it was much the better for it. Otherwise you've got lots of battery contacts to keep clean.

 

[VicMallows]

Another one available here ... and got enough old junk, if anyone want's it. Good in it's day and certainly used it on first few channel crossings.

Vic

 

[jeanne]

If you have any plans, or dreams, of sailing away one day, then dont junk it.
Most islands have airstrips, and they all have a radiobeacon, and they were such an important part of air navigation that I do not think they will be scrapped , even if everyone uses GPS as a first choice.

 

[Robin]

Wonderful device in it's day, cost I believe about £25! It used to take real skill to tune into each station group and a lot of judgement to determine where the nul (point of no signal) was, usually over quite a wide angle. We had one and later graduated to a much more sophisticated digitally tuned Lokata which cost around £200 I believe and which is still on board. Some aero beacons are still active though I haven't put batteries in to try ours for some years, it is however a spare handbearing compass. In a few years they will go for much monies on the Antiques Roadshow.

 

[deejames]

It's basically a radio with a very directional aeriall. If you are a bit lost, you wave it around until you detect a simple morse-code signal from one of many radio-direction-finding-equiped stations - e.g. St. Catherines or Jersey. You then find the "null" which is where the signal is weakest. That should give you a bearing. Do this again on another two stations and you will have a "cocked-hat" on the chart which, with a bit of luck, won't cover an area larger than a couple of hundred square miles. I'm old enough to remember when the Seafix was as good as it got for the small boat sailor. No Decca or GPS. Crossing the channel from Cherbourg on a Westerly Centaur, you stood in the forecabin, poked your head out of the forehatch, waved the Seafix around a bit, wrote the morse code and the bearings on the back of your hand with a biro, plotted the lines on the chart, and - with a bit of luck - you would have some idea of which side of the Isle of Wight you were likely to end up !! Keep it, if only as a reminder that it is now taken for granted that, with GPS, not only do you know where you are, but that where you are is quite likely to be where you hoped you might actually be !!

 

[Vara]

And the best bit of them was that you could listen to The Archers while pretending to do proper nav,also could get weather forecasts,but not much use as even with their help you didn't know which sea area you were in.
Once used one to guide me into Brighton Marina(BM) in fog,put me straight in between Palace and West Pier an error of two miles from 6 miles out,when I repeated exercise in good vis it was spot on!
Still got them though Seafix and Lokata.

 

[Gordonmc]

Use for a Rf direction finder:
1. Remove compass from top of receiver.
2. Remove handle from bottom of receiver.
3. Fix compass to handle.
4. Bin the receiver.
5. Use the conjoined compass and handle as a bearing compass.

 

[dmayes]

Don't forget that when you do find a null in the transmission it can be 180 degrees out, there will be two nulls in a circle. As stated before, most airfields have beacons and the radio stations themselves can act as positions, if you know where the transmitting aerial is located. It is useful to show youngsters such as Scouts how to do triangulation using aero beacons and radio stations on OS maps. I still have a working Nasa RDF plus the compass/handle from a Seafix as described in the last post, makes a very good DF compass and you don't need the handle if you don't have much room.

 

[Oldhand]

Did you have to ask? All the replies are making me feel too old!

 

[Rivers & creeks]

The old RDF was the source of my greatest navigational triumph. About 25 years ago (as a teenager) we were crossing from the Isle of Man to the Fylde coast. Dad and his shipmate convinced that we were still 15 miles off the coast, they didn't trust this new fangled RDF and relied on DR. I took a back bearing from Ronaldsway and the point of Ayre (south and north of the Island, 30 miles apart). Showed we were 4 miles off. 'Rubbish' they say. 5 minutes later, Blackpool tower appears out of the mist.

No chance of that nowadays. The wife never says 'where are we'; she says 'pass me the GPS, I want to see where we are'.

 

[Guest]

Not Seafix - but a Marconi job ... on a Tanker we had been suffering bad weather in Indian Ocean for days coming from Singers to Cape Town .... no sun sights or stars ..... Walked past the DF set and thought well nothing to lose !! So took some bearings of beacons over large distances !! Corrected them for GC errors and plotted LIGHTLY ... as I didn't want evidence of my foolishness ... bang - there we were os it suggested .... way off course. I passed it on to next watch etc. Anyway not long later we managed to catch sights and lo and behold the DF position had been reasonably correct !!

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