Using Radar for navigation..

beancounter

beancounter

Well-Known Member
Joined
28 Feb 2003
Messages
1,334
Location
Cambridge
Visit site
Spent an enjoyable day on Sunday doing the RYA radar course. I'm now looking forward to practising with the kit on the boat when we're back on the water.

Whilst covering the topic of using radar as a navigation aid, the thought occurred to me - how many people actually do this?

I'm probably missing something obvious, but assuming you've got GPS, why would you not be plotting your position from that? If the GPS packs up, then there's a good chance the radar will too (flat batteries/electrical problems etc.) Even if it's a problem with the GPS set, lot's of folks have back-up unit (hand-held or whatever). In poor visibility, you can then focus on the radar for collision avoidance (and if it's not poor visiblity, why are you using the radar for bearings and not the hand-compass?..)

signed

Confused of Cambridge...
 
Having been off the "oggin" for some time we were having a play with the radar/plotter on Sunday morning. I know it is easy to say, on a bright and clear morning, when everything can be confirmed by Mk. 1 eyeball, but I would have been comfortable navigating up the Solent and into the Beaulieu by radar. With the overlay on it is superb, blips can be verified as nav marks etc., which makes the moving hazards so much easier to identify.
 
I got into the habit of backing up GPS position with a radar plot after this little incident (I hope the picture is clear enough for you to see that our boat is not in the marina but probably closer to Pizza Hut several streets inland)

Losttheplot.jpg


Visibility hadn't been good when we were entering this harbour - I was staring at the plotter telling my husband to keep going for leading line to entrance. He said it all looked wrong and took decision to turn there and then - the correct decision as it turned out.

Contacted Raymarine who said that they'd had a couple of calls from Portugal that week about odd goings on and apparently Americans were playing around with the GPS system.

After that I lost my blind faith in the plotter and was always happy to overlay radar for a double check if I had the slightest doubt.
 
The prime use for most of us is collision avoidance. Using a radar for location is better described as electronic pilotage rather than electronic navigation, in situations where you do not want to be constantly checking the chart - like Mk 1 eyeball pilotage?
 
Steve,

to clarify a little, we have a somewhat aged radar and no plotter, so we would be maintaining a chart-based plot in poor viz.

(in fact, the age of the radar is such that I occasionally feel the urge to grab the VHF and say things like "Red Leader, I have hostile contacts at Angels One-Five"....)
 
You can put a range circle around yourself and use it to ensure a pre-determined distance off. A very nice way of ensuring you are always in safe water without plotting a position. Although of course one does also plot a position!!
 
[ QUOTE ]
Using a radar for location is better described as electronic pilotage rather than electronic navigation, in situations where you do not want to be constantly checking the chart - like Mk 1 eyeball pilotage?

[/ QUOTE ] Yes, exactly. But unlike the Mk 1 eyeball, radar can give a fairly accurate range, as well as direction. If the crew is ever looking bored, get them estimating distances to vessels or coastal features they can see. Then you can debate what the prize should be for the closest to the range established by radar (making the coffee, not making the coffee, etc.).
 
Yup, those features are present & correct.

I may have used a smidgeon of poetic licence regarding the age of the set, (made by Apelco, "A Raytheon Company" according to the manual) but it is yer basic 1990's green screen jobbie.

Still, when the fog kicks in, if it helps me see the Emma Maersk heading out of Felixstowe, that's good enuff.
 
I use radar for as an aid to navigation and collision avoidance, an excellent tool, if used correctly. Piloting up a river/estuary in low/nil visibilty relying on GPS alone is not a clever thing to do. IMHO
I switch my radr on when entering a strange harbour, even in good visibilty, helps to build a picture of the harbour/river/estuary seeing objects/features on radar and in the flesh so to speak, easier to recognise the features, when the visibility is bad.
I could enter the Dart confidently on radar alone and know the boats moored in the river, the moorings etc, because I had done it on radar with good visibilty, plus using your echo sounder helps a great deal!
 
only time i have actually used radar for nav is peasoupy fog around a port (mareseille) when i knew from calling others it was fine outside/offshore. So i cd creep out and "see" walls, befoe all clear - and no boats at all!...
 
I'd go further and suggest that with a combination of radar and hand bearing compass you can very accurately plot your position from 1 recognisable charted object - the compass is excellent for what it's designed to deliver; the bearing. The radar will deliver the distance exactly.

Re plotter v radar etc - as has been said over and over again on here and in published material, continually cross referencing 2 or more sources of information is good practice; never forgetting the Mk 1 eyeball.
 
I thought about that but the error mysteriously appeared one day and disappeared the next with no fiddling with plotter settings. I checked datum and it was ok. Still made me nervous.
 
[ QUOTE ]
You can put a range circle around yourself and use it to ensure a pre-determined distance off. A very nice way of ensuring you are always in safe water without plotting a position. Although of course one does also plot a position!!

[/ QUOTE ]

One of the greatest advantages of Radar for entry into out of restricted waters etc. is Parrellel Indexing ...

You can construct a set of courses with turns etc., on the screen based on land shown on screen ... with max - min dist. off ... stay with land echo in between the lines ... bingo. Easy.

Range and bearing ... why piddle around with compass errors etc. - use ranges to determine position ... the cocked hat will likely be better than obtained from bearings ...
 
You must log in or register to reply here.

Share this page

Top