Background wanted on Decca Yacht Navigator IV

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CarlR

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My new 'second hand' yacht has a Rascal Decca Yacht Navigator IV unit that is giving me a Lat/Long position. From internet searches I believe that the DECCA signals were turned off in 2000.

Can anyone tell me how this unit may still be working and information on accuracy(currently 1/3 nm out compared to chart ) or conversion to WGS84.

I'm new to using forums so any help appreciated.

Thanks
 
Yes Decca was turned off in the Uk in late 99 or early 2000. We last used it to find the area of total solar eclipse in the channel on Aug 11 1999. Ours then died, the system shut down soon afterwards (no connection AFAIK)
Some Decca sets were convertible to GPS, ours was too old, but yours may have been. It was not a particularly attractive proposition as it cost as much as the cheapest GPS sets and had far fewer capabilities into the bargain. (I think ours was a Decca III and that the Decca IV was convertible) I expect they used only the minimum number of satellites.

Thats all I know
(Racal not Rascal I think you will find)
 
If your boat is on a mooring stationary it may be remembering the last Lat and Long for that position before the system was shut down.
 
[ QUOTE ]
If your boat is on a mooring stationary it may be remembering the last Lat and Long for that position before the system was shut down.

[/ QUOTE ]
I concur. I think the only dual DECCA/GPS instruments were made by Phillips and yours is not one of those. Keep it at home as a collector's item and replace it with a nice modern GPS receiver or a chart plotter.
 
I am wondering if your Mk iv is a Philips rebadged. This had three small coloured lights which a green was on when OK.
The display was large and clearly read and it was pure Decca. However many folk have kept them as they included a voltmeter function and were remarkably accurate compared to some Furuno and other equipment. You just need to find out how to get to the menu and find the voltmeter selection:)

I viewed a boat a few days ago which had one in the wheelhouse which I thought was a good idea. as visible night or day to two places of decimal /forums/images/graemlins/smile.gif
 
[ QUOTE ]
Mk iv is a Philips rebadged

[/ QUOTE ] I thought they were made by Philips just like the mkIII s were. That had the "traffic light" signals.
I have forgotten how to get the voltmeter function but as you say it was useful.

I dont remember anything about the earlier versions.
 
Hi Freewind
I only have the manual at home however it only talks about DECCA, nothing about GPS - plan to go and see the boat again this weekend - it has the traffic lights on the right hand side and at the back of the manual, an added leaflet on a Leica ap navigation GPS Survivor antenna. Hence it may have been coverted to GPS. Any idea how I can check for certain and what datum it might be using? Do I just live with any difference to WGS84?
I'll also check out the voltmeter function, V to special functions, then > and then V to battery voltage.
Many thanks for your help.
Carl
 
[ QUOTE ]
Any idea how I can check for certain and what datum it might be using

[/ QUOTE ] No but the most likely for a gps is WGS84 I'd have thought. I guess the old Decca used OSGB but in those days we had not heard of different datums .

I think Id dump it. but how about a photo of it.
 
[ QUOTE ]
L.ent.10.... I think

[/ QUOTE ] L ent 10 ent rings a bell but i have no idea what it gave. We used to use the timer as an egg timer I seem to recall.
 
Assuming you are in the UK, the maximum difference between charts referenced to OSGB36 and WGS84 is around 200m and certainly less than the 1/3 nm you are seeing.

I believe the the Leica GPS Survivor was a smart antenna in that the receiver was in the unit as the antenna which output NMEA. It is also very likely that it only outputs WGS84. Is your chart as old as the ap Navigator and referenced to OSGB or other datum?
The ap Navigator Mk5 had a feature for correcting output to your local chart datum by entering delta lat and delta long values. Does the Mk4 have the same facility?

The Survivor antenna was also at least 6 inches in diameter so it should be easy to spot if mounted above deck.
 
Hi Carl, Could be a week before I get on board and can check instruction book. Can't remember from memory but it is a Phillips . Will PM if I have anything useful to offer but I know that somewhere in the setup is a function to change from one to the other.
 
Hi geoid ( and all others who have helped )
There is a GPS Survivor antenna on the pushpit but the leaflet does not talk about what datum it will use. My chart is a recent one and is to WGS84. The Mk4 manual does say that you can do a correction so I'll give this a go when I next visit the yacht.
Do you think that this correction will hold good for a reasonable distance as I'm about to move the new purchase 100nm down the coast overnight?
Many thanks to all.
Carl
 
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