This is a question that I often got. Should I take a radar or an AIS ?
I will try to answer.
An AIS definitively. You should get an AIS. Receiving AND transmitting AIS. A real AIS class B. Its not so expensive, really reliable, and takes really little power. Negligible amount of power.
An AIS is obligatory on every commercial boat. Cargo ship, Container ship, trawler, fishing boat… And it’s checked each time they sail close to a land station. And more and more pleasure boats have it too. So if you have an real AIS, all these boats will see you, and you will see all these boats on your plotter. (If you have connected everything correctly) So even if you are a mini (6,5m long sailboat) and you cross a ULCV container ship(400m long), she will see you. And if there is a collision course, an alarm will trigger in your boat and in the ULCV container ship typically 15min before the crash. And you will see, she will then turn.
For me, an AIS is the best invention since the GPS. With an AIS plugged to a plotter, crossing a busy cargo ship road by night like Gibraltar or Ouessant, piece of cake.
So an AIS yes, get one. Witch one ? well, 3 years ago when I was still working in this business, all the AIS class B that I have seen (a lot of different brand) had the exact same PCB inside. That includes big name and no name AIS. So basically they were all the same inside. Just the housing was different. So it doesn’t matter.
What about a radar. That’s more difficult to answer.
An AIS is almost perfect, but not every boat is equipped. Buoys, fishing buoys, big floating objects do not have AIS either. A radar will see these few targets without AIS (and also the ones with AIS). If it’s a good radar and well tuned. But a radar is expensive, big installation, some maintenance, it’s not the most reliable instrument and it takes a lot of power.
So that the question that you have to ask yourself, do you want to spend a lot of money in this equipment to see this few targets without AIS ?
Another really good use of a radar is in a mooring bay. When I arrive by night in a mooring bay, I stay a little bit off the bay 5 minutes, I plot every boat in the radar, and I can see the best spot where to put my boat. A radar is also a perfect instrument to measure precisely the distance between you and the next boat or the shore (if it’s not a sand beach…)
If you want a radar, which one ? I don’t know. I have a Koden radar, 4kw, extremely happy with it, I can see small fishing buoys at several NM away, so everything bigger than that even better. It’s has the auto plot function, alarm zone, alarm in case of collision course, all tunable. Extremely reliable, so I sleep confident when I need too or when I can. It’s always working and will work for a long time, I know it by professional experience. But unfortunately Koden is not making radar with the new technology yet. That’s why, unlike any other instrument where I do recommend Koden, I am not so sure about koden radars as long as they haven’t released a radar with this new technology. Because this new technology is a big plus for a sailboat.
Few years ago, there was a breaking technology that came to civilian radar. Its started with manufacturer for big professional radars (Kelvin Hughes first), and came after to pleasure boat equipment manufacturers. It’s almost everywhere now but not with Koden. Koden is always a bit late on new technologies. They like to take their time to make a good product out of it.
This new technology of radar is called broadband radar by some companies or CHIRP, 3G, 4G by other. What is new ?
Since the invention of the radar, the radar was sending a electromagnetic pulse (4Kw in my radar for max 1uS) and listening the echo from this pulse. By the time it takes to come back and the speed of the light, you know the distance blablabla you know the story. To do so, a really important component inside the antenna is the magnetron. An expensive electronic component that needs to be changed regularly, that needs to be warmed up to work and it has a bad efficiency. All that is taking a lot of energy.
New broadband radars are not working that way anymore. It’s not sending a pulse produced by a magnetron but a electromagnetic chain at much lower power produced by special transistor (coming from cell phone technology, it has to deal with 10GHz). The rest is the same, waiting the echo blablabla. What does it change ? A lot.
- Most important for now and for us, this new radar take much less energy, really important on a sailboat. I am talking about 1/3. It’s a big change.
- Because the electromagnetic waves has less power, it’s less dangerous. Apparently you can sit in front of the radar antenna without risk… at your own risk.
- The image will be better in a near future, already better ? maybe, that I can’t say. What I have seen with my own eyes tells me, that a good magnetron radar had better performance than a new broadband radar. But it was few years ago and the comparison was between a complete mature technology with something brand new… So today’s new model that I haven’t seen are maybe with a better image.
- It opens Doppler effect. And that’s a huge door. With a pulse, it’s really hard to measure the frequency, so the shifting of the frequency, nop. So no Doppler filter.
With the new technology, it’s much easier. And Doppler radar opens a new world in filtering the sea and rain clutter. I am not going to explain that here but its a complete new way to filter and its much much better. That´s maybe why military radars are Doppler since a long long time… - And of course, no need to change the magnetron as there is no magnetron any more.
So if you want to buy a radar tomorrow for a sailboat, I don’t know what to tell you. This new technology of radar is better, but I don’t know them for pleasure boats. You should take a look at Garmin, Raymarine, Navico group.