Fitting radar

[Oli]

Now we have the boat we hope to stick with for the forseeable future, and with Alderney, Weymouth and hopefully a number of mid channel trips ahead in the next few months, we're seriously considering fitting a radar system. The thought of being 20 miles offshore when thick fog comes in and not being able to see a cruiseliner is a nasty one.

 

So I'm looking for some advice please...

 

Firstly (and I'm sure I know the answer to this one), those of you that have it, would you recommend it?

 

Second, we have the Northstar M121 plotter etc on board so are looking to get the Northstar BR24 Broadband Radar (same as the Lowrance/Simrad Broadband Radar). Do any of you own it/seen it in action/read any reviews?

 

Finally the old question of which radar reflector! We currently have an octahedral, but is it really good enough?

 

Thanks as always

 

Oli

Edited March 21, 2010 by olimain

[petesnr]

I've used an octahedral for years and one of my marks is directly on ferry route--so far they have always changed course at some distance away!!

 

Peter

[Bob F]

Hi Oli,

 

I haven't seen the Northstar BR24 in action, but some of the reviews I have read have been very good. It was specifically designed to integrate with the M121 display. so it's the perfect choice for you.

 

The BR24 is one of the new range of radars that use low power FMCW (frequency modulated continuous wave) technology rather than the older, high power, plused radars. This has a number of advantages.

 

- you don't have to wait for a magnetron to warm up, so the radar picture is available instantly from standby. There is still an initial warm up when first truned on, but even this is quicker than the pulsed radars.

- the transmitted power is very low so there is no radiation hazard.

- because it's low power it means the battery consumption is low, so leaving it on at anchor with the engine off is not a problem.

- FMCW will give much clearer short range resolution with no dead zone around the boat.

 

Regarding ease of use, it is supposed to be very easy to operate and requires little or no tuning, so it should almost be just a case of selecting the oppropriate range and that's it.

 

The octahedral reflector is fine, so long as it is mounted high enough. This is a passive reflector, meaning it is relying on reflected radar waves to be seen by a radar. If you can afford it, a far more effective system is the active Sea-Me reflector. It detects radar energy and then transmitts back a much larger pulse of radar energy so you will appear bigger on a radar screen and have a much greater detection range. It also has the capability of giving you an automatic ship detection alert.

 

cheers

 

Bob

[gjb]

Hi

i have the navman 8084 with Navman Digital Radar and find this very good and think the northstar is the same unit but don't know about the BR radar

cheers

graham

[great white]

I can not comment on the broadband radar, but would say that having a set onboard is a real asset when the weather closes in and you start to hear the fog horns going.

 

If mine ever went U/S, it would be replaced ASAP

 

 

worst trip so far was when vis went to zero on the starfish grounds, turn on the radar and the alarm and relax [a bit]

 

Charlie

[Oli]

Thanks for replies so far, all very helpful as ever.

 

From speaking to a couple of shops today and watching the various YouTube videos, it really does look like it gives excellent definition at close range - even picks up birds sat on the water!! How high does the octahedral have to be Bob? In the past we've just had it on the cabin roof...

 

Sounds pretty nasty Charlie! Last summer over on the 9 mile the fog came in thick and fast. It wasn't a pleasant experience hearing the rumble of the Condor long before I could see it.

 

It's very expensive but definitely an investment and something I'm starting to feel is a must with the sort of trips we are doing more and more of...

Edited March 22, 2010 by olimain

[Maverick Martin]

Oli

 

I am thinking the same as you in as much as I now feel I want no need radar. Unfortunately for me I have spent out a bucket load of cash on the boat both this and last year so no budget for electronics yet I am planning however to have a full replacement set of electronics next year that will probably be Raymarine unless anyone convinces me different

 

Martin

[AHoy]

I will second the value of radar for the ability to see in the murk/dark and further than with the naked eye in reasonable vis. As well as ship target plotting the other big benefit is for general navigation i.e. distance off, radar fixes etc..

 

I haven't had a chance to evaluate the "leisure market" CW radars, but have been doing some background reading due to professional interest. It would appear that medium to long(er) range performance may be an issue, so if possible get a real seagoing demo with a bit of a sea running (to check clutter performance) and check out some identifiable targets at longer range, say 4 to 6 miles.

 

The claimed power savings are partly due to the use of new technology in general and would also apply to pulse radar.

 

AHoy.

 

[wrasster]

May we chuck a different note in to this discussion?

 

We're just looking at radar for the Aquafish, and the chap in Colchester has suggested a Lowrance HDS Combo, with an in-hull transducer, and a LRA-1800 2 KW radome.

 

As we know nothing about them, has anybody any experience or advice regarding the Lowrance set-up, and/or alternative suggestions. Also, some research we've done suggests the in-hull transducer is not as effective in fish-finding as one through the hull - any thoughts on that?**

 

What a minefield it all is! Still, if it saves us running into one out on the briny, it has to be worth it!

 

Dennis & Steve

 

**sorry got that wrong - not through the hull, but transom transducer is what he's looking at (Steve doing the posts as usual and cocking it up!)

Edited March 24, 2010 by wrasster

[Oli]

Ahhhh the costs don't stop. Apparently for accurate chart overlay I need a heading sensor!?!

[Maverick Martin]

Ahhhh the costs don't stop. Apparently for accurate chart overlay I need a heading sensor!?!

Yep but if you have autopilot you may already have a fluxgete and if its a raymarine the computa thingy can give the relevant info.......I think

 

Martin

[Oli]

AUTOPILOT! Bloody luxury over on Awol isn't it!!

 

Afraid there's no such luck on SC

[great white]

AUTOPILOT! Bloody luxury over on Awol isn't it!!

 

Afraid there's no such luck on SC

Auto pilot who needs them

 

I have Dan and Sam

 

trouble is they eat too much, and catch the biggest fish

 

Charlie

[Bob F]

Dennis, Steve

 

We have a Lowrance set up on our Aquafish. LRA-1800 radar with the older LCX12C display and a separate HD fishfinder. Nowadays the HD fishfinder is integrated into the new HD displays, I believe.

 

The LRA-1800 Radar is the traditional older style pulsed radar, so you might want to consider going for the new Lowrance Broadband radar, which is the same as the Northstar radar that Oli is thinking of fitting, and uses FMCW technology with the pro's and con's mentioned in previous posts in this thread. The main con's are that it is relatively unproven technology (so there may be a few software updates to remove bugs in the first year), and there are some doubts about the mid to long range performance.

 

On our boat the LRA-1800 performs very well, but it does need to be properly set up and tuned to perform properly, and the set up process is a little complicated if you do not know radars at all. The new broadband radar is supposed to require very little set up and tuning, so should operate well straight from the box.

 

So, the choice is old and traditional with known performance, but needs proper tuning, or new broadband which is easier to use and set up, but the performance is unknown and there is likely to be a few bugs to content with.

 

Regarding transducer for the fish finder, we use the standard transom transducer but have fitted in the central bay under the batteries, so it is operating as an in-hull transducer. We have it mounted in an oil filled plastic box that is bonded to the floor. The performance is great. I can post some pictures of the box I made.

 

If you go for the LRA-1800 radar I can set it up and tune it for you, if you have any difficulty setting it up.

 

cheers

 

Bob

[wrasster]

Bob, Thanks for all that, it's been a great help.

 

As complete technophobes, we will be very grateful to take you up on your kind offer of help when the boat arrives and we settle on a radar kit. We have been put off the broadband a bit, as we understand it doesn't work too well at distance, and as the LRA 1800 comes well recommended and apparently relatively easy to use, we'll probably go for that.

 

Very interested in your comments regarding the transducer - sounds like a very sensible option.

 

Look forward to having a good chat in the near future!

 

Thanks again,

 

Dennis & Steve

[Adam F]

I'll just second what others have said, but without the technical info.

 

The radar on JV doesnt get used often as 70% of our fishing is relatively close inshore and during the day...

 

... however for the other 30% of the time we are offshore, mid channel or out at night - then I find the radar invaluable.

 

Put it this way, leaving Alderney last June with 70 miles to run across the channel in thick pea soup fog, the radar turned the situation from a constant worry to a minor inconvienance - 'seeing' the tankers on the radar was hugely helpful - without it, it woudl have been a very slow, long and dangerous trip back over.

[fisherman1055]

for those of you looking at radar reflectors the attached paper makes intersting reading

 

unless you have a lot of money the octahedral reflecter perfoms better than most

 

Tony D

[fisherman1055]

File will not upload

 

e mail me on fisherman1055@aol.com for a copy

 

Tony

[Rob]

 

I thought I once read that a radar working on a boat will act as a reflector and make that boat show up - though I could well be making this up!!!

 

Or maybe there are different frequencies so maybe you will show up or maybe you won't.

 

Rob

[Oli]

Pleased to say we'll be fitting this on Saturday (please God let the weather be half decent).

 

While we're going to be having everything in bits in an ideal world I'd like to fit a heading sensor as I'd really like to be able to accurately overlay the radar on the chart.

 

The question is, will any fluxgate compass (providing it is NMEA 0183) fit the bill or do you think (being the marine world) it needs an exact make and exact model that they can charge hundreds for. There are a fair few on eBay under

[wotu2uk]

I believe that to correctly align the overlays, the compass needs to be a rate compass rather than a basic fluxgate type.

 

this from Wikipedia:

The basic fluxgate compass is a simple electromagnetic device that employs two or more small coils of wire around a core of highly permeable magnetic material, to directly sense the direction of the horizontal component of the earth's magnetic field. The advantages of this mechanism over a magnetic compass are that the reading is in electronic form and can be digitised and transmitted easily, displayed remotely, and used by an electronic autopilot for course correction.

 

To avoid inaccuracies created by the vertical component of the field, the fluxgate array must be kept as flat as possible by mounting it on gimbals or using a fluid suspension system. All the same, inertial errors are inevitable when the vessel is turning sharply or being tossed about by rough seas. To ensure directional readings that are adequately stable, marine fluxgate compasses always incorporate either fluid or electronic damping. An alternative is to use a 3-axis fluxgate magnetometer to provide a 3D flux vector, and the magnetic heading is derived from the flux on a plane perpendicular to gravity, thus providing immunity from pitching, and rolling.

 

Fluxgate compasses and gyros complement one another nicely. The fluxgate provides a directional reference that's stable over the long term, apart from changing magnetic disturbances, and the gyro is accurate over the short-term, even against acceleration and heeling effects. At high latitudes, where the Earth's magnetic field dips downward toward the magnetic poles, the gyro data can be used to correct for roll-induced heading errors in the fluxgate output.

 

The latter is a rate compass, I believe, a combination of solid state gyro (piezo) with a compensated 3-axis fluxgate magnetometer, an example being the Simrad RC42

Edited April 14, 2010 by wotu2uk

[Oli]

Thanks for all of that. It seems you may well be right but before going to the extra expense of the rate compass over a standard fluxgate, you can understand me wanting to be sure that one won't do the job for the other...

 

I may try a call to Navico (watch this space!).