radar

[mistril]

Season's gruntings to one and all!


My LM27 ' Charmar' which I'm still fettling, came with a 15yr old Furuno radar that seems to work but I'm reserving judgement as to its worth until we can get out on the oggin to try it properly - it seems a little confused at the moment but then I suppose it can't give a clear return when it's on the hard and surrounded by yachty clutter. My question concerns the visibility of radar - if my radar is transmitting, does that make my vessel more visible to another vessel that receives the radar transmission? If the radar helped with safety in darkness and poor weather then that might be a reason not to condemn it too quickly. Any thoughts as the turkey disappears?


thanks

Charles

[oceandancer]

Hi And Happy Christmas,

Just keeping out of the kitchen!- No, RADAR is designed only interpret reflections from its own transmitter. Having an 'active' RADAR'  should have no effect on detectability unless it conflicts with the frequency and pulse rate of the viewing radar, unlikely as small marine radars are equipped with a fairly wide range of oscillator crystals. If two radars do conflict the effect will be that tracks run around in a spiral - so called 'running rabbits', this hardly ever happens in practice.

Radar interpretation is quite an art, the many settings on the receiver are confusing and the best setting will change with weather and temperature. The wrong setting can obscure targets altogether so practice is required to get the best gain, anticlutter etc.

If you are concerned mainly with avoidance of large ships then an AIS receiver integrated to your plotter is worth considering. This will give warning of approaching large vessels which are obliged by maritime law to transmit their position , course and speed over VHF. The AIS receiver can provide much better interpretation and warning of potential course conflictions and is more of a 'heads up' device requiring far less expert interpretation.

The name of the vessel is also given which means that you can call up on VHF if you believe a large ship has not seen you. You also get information on closest point of approach (CPA) and time to closest point of approach (TCPA) and together with the predicted time line given by the plotter it can be a very useful tool in a busy shipping channel.

Small vessels and many yachts do not have AIS transmitters, they are quite expensive at present, so in poor visibility the RADAR is still quite useful as a raw detection aid.

My Radar is still fitted but rarely  gets used whereas I frequently use the AIS information to avoid shipping in the Solent. It should also be remembered that Radar is very battery hungry. It's also a pain to disconnect when the mast comes down.

Happy Christmas

Mick

[jandane]

Mick...I totally agree. I have the AIS installed in my LM27 and linked to the Garmin GPSMAP and it really is a fantastic feature in coastal waters. By the way, RADAR can be seen from other receivers.......the Airforce use anti search radar homing missiles capable to detect a transmitting RADAR, launch a missile which will go directely for the transmitter, but that is a complete other history.

[nauticalnick]

Hi Charles,
l think l have the same radar as you which came with the boat when purchased some 18 months ago.

So far l think l have used it only twice, the first time having picked the boat up in Weymouth and returning to the Solent the weather suddenly closed in 10 miles west of the Needles so it was a crash course in understanding it but it certainly was very re-assuring to see the buoys and the land appear on the screen. The other time l can't remember !

l think l'll be keeping it but l prefer AIS when in the Solent it's easier to understand than an elderly radar. Of course the modern sets can have chart and AIS overlays but sadly one didn't appear in my Christmas Stocking this year. As far as being seen l would think about theses so called " Active radar reflectors " but they are expensive.

Mick sums it up; heavy on power consumption, take quite a lot of understanding and are a pain to disconnect when removing the mast. Perhaps l'll avoid sailing in Danish waters with the radar turned on !!!

Happy Christmas,
Regards,

Nick

[Charles]

I think Mick has summed it up very well. Marguerite came with exactly the same set up as Charmar and I duly went on a course to learn how to use it. However, we hardly ever use it and skill fade happens quickly. We use the AIS which is built into our small chart plotter all the time. It was reassuring to have the radar as well when crossing the North Sea at night, but that was the only time we used it for real and we ran the engine throughout.
Whether it's worth keeping it depends on the sort of sailing you are going to do. We are fair weather, day time sailors, but if you are planning lots of night or off shore sailing then it might be different. One other thing, in poor visibility Colregs require you to keep a good look out using all available means, and if you have radar that must be included.
With all due respect to Jandane, I think it is only highly sophisticated military radars that can see other transmitting radars.
Hope this helps. Over to you.
Happy New Year!
Charles

[Deleted]

Dec 25, 2016 12:55:03 GMT oceandancer said:

"If you are concerned mainly with avoidance of large ships then an AIS receiver integrated to your plotter is worth considering. This will give warning of approaching large vessels which are obliged by maritime law to transmit their position , course and speed over VHF. "I agree that big boats have to install AIS but they do NOT have to switch it on and I often see vessels supposedly at anchor but clearly steaming along at 20 knots and vice versa.  AIS is good but if you want to see everything around you then radar plus AIS is better. I have both overlaid on my chart plotter which makes crossing the Channel so much less stressful. Your radar will not be happy on the hard in a stationary vessel, it needs to know your heading. Please don't discard it until you have had a chance to practice at sea and learn how to interpret the screen and realise just how useful it can be.

[mistril]

Thanks to everyone as ever - hope the festivities were bearable. I accept the need for some experience with the radar, and I won't condemn it yet. I'd wondered about the power consumption. The mast stepping has been another adventure trying to sort out all the different bits of cable - the radar is certainly a jungle - especially since the blokes who dismantled the mast prior to transport from Windermere to Fleetwood were less than sensitive in the way they disconnected the terminals ................. is mine a one off, by the way? - all the cables exit the base of the mast and then up and under a stainless steel mushroom that locates on a sort of hawse pipe that leads down into the saloon adjacent to the mast support. How it stays waterproof is beyond me - faith, hope and lots of yakumm, I suppose.

Cheers all - let's hope for another summer like 2016 - I missed most of it with changing the boat!

[Deleted]

Dec 29, 2016 16:42:21 GMT mistril said:

That sounds exactly like my set-up and the mushroom does keep the water out. My cables enter the corner of the heads and I allowed a drip loop before putting them in a waterproof box and connecting them to the cable that runs into the wheelhouse. When I have to remove the mast, I can undo the connector and pull the cable out of the mushroom.