Selecting Raymarine components. 12kw vs 4kw radar. ST60 or ST70?

jfm

jfm

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I'm stuck on a couple of things in speccing Raymarine gear for new boat.

Has anyone got experience of using different radar powers? The raymarine SHD open scanner radar whirler comes in 4kw and 12kw. The 12kw is about £500 extra. Anyone know what differnece it makes? I'm used to a 4kw and it seems fine but am I missing a whole new level of visibility?. I asked Raymarine and mentioned in the question that I use it most critically in short range work in busy waters at night, <6nm range, and they replied "12kw is a lot higher output than the 4kw. With nearly everything in this world, bigger is better and in a Radar case the bigger the power output the greater the range and clarity. Again 6nm usage would make little difference at that range between the 4kw and the 12kw"

Has anyone experienced the difference? By the way, my scanner is 6m above waterline so that limits my range anyway. Hence it is the increased "clarity" that Raymarine mention that interests me

Secondly, does anyone have experience of these new St70 instruments that supposedly improve on the St60s that we all know and love? Are they any better? Or worse? I notice hurricane you have an all singing dancing system yet you stuck to St60 not 70. Any reason?
 
The higher power gives greater distance but only if you have the elevation. I doubt 6m is enough. Try asking about the difference in beam resolution of the 12Kw and the 4Kw - the finer the projected beam the finer the detail. Overall for the use you describe I'd save the money for something else
 
Thnaks. Yep, i think with a 6m mast the range is limited by the horizon not the power of the transmitter. They both have the same beam width (a quite decent 1.85degrees) and therefore target resolution. I just wondered if say weak targets (GRP peche promenades or wood sailboats perhaps) might appear better if I zap them with 12kw not 4, and suchlike. Was hoping to find someone who'd tried both!
 
I would say the answer depended on how much you liked goose.

With the 12kw, you could probably stun and partially cook a flock from a couple of thousand yards. The 4kw might pick off the odd straggler, plus a few ornamental starlings.

Even at closer ranges, there is still the issue of "You can't cook a chicken for 35mins at 380'C"
 
Thanks. That's it then. !2kw. I might have a hinge bracket to point it downwards and get some nice Tuna too. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
 
I dont think that the power output will make a lot of difference for the short ranges you say you use it for.

I would be more interested in accuracy - so the biggest open array scanner you can fit - I seem to remember from the short course that we went on that its the width of the scanner that makes it more accurate.

Also another consideration - digital scanners came out about a year ago - Jimmy_the_Builder and I were amoungst the first to get them earlier this year. I understand that the digital bit electronically removes the end lobes and has the effect of (virtually) increasing the scanner's array size - thus making it even more accurate. The new digital scanners can be fitted to either the G Series of the E Series.

Personally, my experience it of two extremes. The old boat had RL80 (Pathfinders etc) and an old small enclosed Raydome. The new boat has G Series and a 48 inch digital open array 4Kw scanner. The new system is significantly more accurate that the old one - often picking out small buoys that the old system didnt.

[ QUOTE ]
I notice hurricane you have an all singing dancing system yet you stuck to St60 not 70. Any reason?

[/ QUOTE ]
The Princess came fitted with a basic Furuno system that I managed to get credited as unused but I didnt see any reason to do the same with the instruments - there are actually more than I need anyway. Think about it - what do you use them for anyway - depth and speed through the water primerily. I couldnt see the point and extra expence of upgrading to the ST70s - now - if you were starting again from scratch, I would probably fit them.

On another matter, an interesting thing happened on our last long passage. I had a DSM300 fitted as our main depth sounder which meant that Princess had to fit a second tranducer into the hull before she left the factory. The DSM (Digital Sounder Module) feeds a relatively simple fishfinder service to the G Series GPMs for very little extra cost. The newer DSM 400 is a bit of an overkill IMO - and I dont actually fish anyway. This meant that the old standard (Seatalk I think) depth sounder remained connected to the instruments. Well on our last passage the enevitable happened - after all, these things are only computers in boxes and the DSM failed (probably crashed). Rather than power everything off and rebooting the entire system, we decided to run without the DSM and "hey presto" the old Seatalk ST60 seemed to automatically pop back in and run the depth instruments - so we actually have, unintentionally a backup depth/sounder system as well.
 
Yep, 4kw digital seconded. Scarily good at picking out small targets (although I would quickly add that Hurricane has much greater experience of using this kit than me).

Cheers
Jimmy
 
I'd say that, dependant upon how clever the digital processing, is the extra power could make quite a bit of difference. The stronger the beam the stronger the return, meaning that targets that wouldn't show up on a lower power radar will be visible on the higher power system. We're talking about objects that are at an angle or maybe not a particularly reflective material.

The idea of the digital processing is that it will pick out something that behaves differently from the background and clutter and the stronger the signal you can feed it the more data it has to work on (bit over-simplistic I know).

With the radars I worked on some years ago, switching to high power would usually improve clarity at shorter ranges, especially when there was lot of clutter (actually it would even on some of the stuff without digital processing once you'd tweaked it for a better picture). That's especially true in poor conditions such as drizzle, etc.

We were taught the same as well. High power was almost always desirable but was a trade off against being detected as a threat by radar warning systems. Not true at a 1/4 mile of course but a good general rule.

The above is largely on experience with military systems but the leisure stuff now seems very comparable with the best military kit of 20-30 years ago.

Edit: you got it spot on in your second post which, as usual with me, says in about ten words what I've taken 200 to say.
 
12kw extends range and detail at long range. Seems in your case your better off with 4kw, unless your over 50m long to get the vertical height, and cruising oceans. /forums/images/graemlins/wink.gif 12kw mounted low could be a waste.
 
Weird debate this one!

Since when anyone is interested in tracking obstacles at more than 10nm or so?
Unless in command of a jet fighter, of course.
Longer distance scanners are for weather monitoring, nothing else (*).
For this reason alone, and considering the Med usage, the additional 500 quids are worth the investment imho.

*) PS: in this respect, it's totally irrelevant how high the mast is, obviously.
 
Re: Weird debate this one!

Mapis, you make a very good point there, which I hadn't thought of. The high power (and this digi processing, which assigns a different colour depending on the target, so a ship in a rainstorm appears a different colour from the blob of rain) mean it would be good for seeing rain and long distance weather. That's especially useful in the Med with all the special microclimates eg bay of Genoa. That alone justifies the £500 imho. I think I'll give it a go.
 
Thnaks for that insight GOG. Makes sense. Mapis made a great comment on weahter tracking above, too. There's no cut and dried answer to this question, but I think I'll give the 12kw a go and see what happens. At least it gives a wider spectrum of experiences across the forum! Thanks
 
Re: Weird debate this one!

Yup, surely the digital processing, coupled with the colour screen, is a further improvement.
But even my very traditional furuno, with its monochromatic CRT, can easily spot thunderstorms and/or rainy clouds.
Just a matter of fine tuning it a bit, and knowing what to look for.
On a long(ish) passages, using the screen mark, you can also see in which direction and at which speed the storm is moving.
I can't remember one single occasion when I used the radar at its larger scale, other than for weather tracking.
 
Thanks Hurric. Great info as ever.

As said above, I think I'll get the 12kw just to try it out and becuase of the weather thing mentioned by Mapis. I also suspect (just a hunch) that firing 12kw will give more return data for the machine to process and potential better clarity.

Yes, the width of the scanner determines resolution. The 6 footer has 1.15deg beam width, the 4 footer has 1.85deg. I can't practically fit a 6 footer though on an 18m boat cos it would look like a helicopter.

I'm ordering the new Super HD digital, as opposed the the earlier HD digital that was the only one available when you did yours. Dunno how much better SHD will be over HD. Raymarine website doesn't explain well the difference but they emailed me this: " The main difference that you would notice is the better clarity due to a more intensive digital signal processing done by the SHD scanner. It is that good it has a feature called 'Bird mode' which it looks for birds on the surface of the water to help you locate where the fish are"

I'm not interested in "Bird Mode" (though it is a nice switch to have on the dash for showing off to your mates /forums/images/graemlins/grin.gif) but any extra clarity is good.

I dont fish and so am not interested in any of the DSM stuff. I only want a normal depth sounder. However, Essex Boatyards specced a forward looking sounder on my boat, which feeds a colour video forward sounder image to the E series display. It looks a bit useless to me so I might remove it but if it has a thru hull transducer I'll leave it and use it once in a blue moon. And it gives me a back up, which is nice to have as you say
 
The scanner that I have has "Modes" which come up on the G Series. I seem to remember Buoy Mode, Harbour Mode - Coastal Mode and Offshore Mode. However, I believe that these are just presets - that is a setting where you can "twiddle" the gains and filters and store them so that they can be recalled for later use. I guess that "Bird Mode" is just one of these presets and looking at the manuals, it seems that there is also a Super HD Controls sub menu within these presets. Only a guess - mind you.

I rarely fiddle with the gains and filters anyway and tend to leave everything on Auto. From memory, the only time I found twiddling them useful was when we had a rain storm a few miles off and it was possible to "tune out" the rain to see the shipping underneath.
 
There's got to be a joke in there somewhere, surely - 'buoy mode', 'bird mode', Essex Boatyards... come on, someone must be able to stick this together and get a punchline! /forums/images/graemlins/grin.gif

Cheers
Jimmy
 
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