Do you need to have radar on your cruising boat? The short answer is: “No” but the long answer is: “Maybe”.
It really depends on where you plan to cruise. Are you aiming your bow for warm tropical waters? In that case you won’t need radar. If you are going to more “unique” destinations where fog is a normal part of life, then suddenly radar becomes a very valuable tool.
Radar has many uses on a boat, many of which I do not find to justify the cost of the unit.
Weather
The most proclaimed reason is to “watch the weather so storms don’t sneak up on you”. The reason is radar will pick up dense clouds in your surroundings and that will alert you to the presence of a storm. Do you know what else detects the presence of dense clouds in your surroundings? Your eyes! You already have them and you don’t have to shell out any boat bucks to buy them.
The classic rebuttal to this statement is: “but what about at night when you can’t see the clouds because it’s dark?” I have found this to be a false argument because at night, the clear blue sky is replaced by a black sky filled with stars. If there is a moon, suddenly it becomes less dark, but still filled with stars! When clouds roll in, patches of the sky lose their stars and become just black patches.
As you spend time out there, you will become very familiar with the different constellations and will quickly notice when you can’t see Orion or Scorpio or Gemini or Pegasus. When you can’t see parts of the sky and the stars are quickly disappearing, you also know that clouds are rolling in and a squall is going to hit soon. Once again, you don’t need radar to alert you to weather changes.
detecting shOres
The idea is if you are entering a harbor in the dark or if you are sailing near land in the dark, the coastline will be drawn on the radar screen. This is useful for identifying rocks that are above water and cliff faces.
I have two major problems with this idea. First, you should never sail into a harbor or near land in the dark. There are so many things that could happen that you just won’t see. Minor things like fishing traps that will foul your propeller to more dangerous things like a submerged log just beneath the surface. If your travels have you arriving after nightfall, either heave to offshore and wait for daybreak or drop anchor outside and enter the harbor at dawn.
My second major issue with this is electronic charts do this exact function and are a fraction of the price! I have Navionics on my phone and it draws all the coasts in perfect detail. It goes one further and also shows me the bathymetry of the sea floor which is something radar still can’t do. Why pay thousands of dollars to have a thing draw the coast when you could have the same thing on your phone for about $20 a year?
If it’s dark out and you can’t see, Navionics will show you the way, if you get hit by offshore fog, Navionics again will show you where land is so you can avoid hitting it.
Land and rocks don’t move. They are also well charted, which means that the electronic chart will help you avoid hitting a shore that you can’t see.
Other Boats
This one has some validity to it. The idea is that if a boat doesn’t have lights on (because they are an idiot) and their speeding around you in the dark, you will be able to detect them on your radar. This also applies to non-idiot boaters who do have their lights on and are simply approaching you. You can set certain parameters so that if someone comes within a certain range of you, an alarm goes off to notify you of their approach.
The reason this is somewhat of a valid point is because AIS does this exact same thing. You can set your AIS to do these same functions but it only works if the other boat is transmitting AIS.
As of right now, all commercial boats have to transmit AIS (Class A signal) while recreational boats don’t have to; and if they do they transmit Class B signal. If you are crossing an ocean, you will have over night passages and you will be sailing downwind (or you are going the wrong way and want to reconsider your route). All other private vessels that are sailing across the ocean will be going in the same direction, so an approaching vessel has to be going faster than you to come from behind or you have to be going faster to approach someone else’s stern. In other words, a head on collision with another sailboat is very unlikely!
The only boats that will not be going downwind will be power boats. These will consist of massive commercial cargo ships that will be transmitting Class A AIS and massive private motorboats which will most likely be transmitting Class B AIS. The reason it’s safe to assume that only massive and expensive power boats will be out there is these boats have to carry enough fuel to cross an ocean! Unlike sailboats which rely on the wind to power them across the great blue sea, power boats need diesel to move, and lots of it! The fuel cost for an ocean crossing will eliminate all possibility of a person with limited financial means being out there on a motorboat. If they can afford the fuel, then they can also afford the electronics that make those boats fancy, and one of the first electronics they will install will be AIS.
Think about how many times you see a derelict sailboat cruising around and enjoying life as the captain gets to freely sail to new destinations and explore the world. Now think about how many derelict power boats you see doing the same thing? Wind is free and food can be found. Sailors can live a happy life on barely no money where a power boat needs to have money to purchase fuel. No fuel, no moving, no exploring, and no living an awesome life! In other words, a powerboat in the middle of the ocean going against the wind belongs to someone who can afford AIS and therefore would show up on your AIS display. A sailboat in the middle of the ocean may belong to a happy boat person who is traveling the world on a tiny budget (much like we have been doing for the past 5 years) and doesn’t have AIS but will be going the same direction that you are!
To summarize, AIS is wonderful but only works if the other boat also transmits AIS. Out in the middle of the ocean, everyone is going to be moving the same direction so if someone isn’t transmitting AIS, they will not approach too quickly. Where this becomes a big problem is sailing through island chains where boats will be traveling in all directions and may not be transmitting AIS! Here is where radar becomes very helpful as an adjunct to AIS. If anything approaches, transmitting or not, it will be detected by one of the two systems and you will be notified of their approach!
fog
This is the real reason to have radar! Storms can be seen with your eyes, day or night, other boats can be seen by keeping a proper watch and using AIS, but fog is blinding! Thankfully, when fog rolls in, the winds are also light or nonexistent, so if you are sailing you will stop moving. This means that if you are purely sailing out in the ocean to destinations that are not routinely covered in fog, and fog appears; you will come to a stop and if you do bump into anything it will be slowly and hopefully less damaging.
What if you are sailing the foggy coast of Maine or near England? The wind can die as the fog rolls in but that doesn’t mean the tidal currents will slow. Suddenly, you might find yourself with no wind in your sails, no visibility, and being swept away with the tide.
Rocks and shorelines are still visible on your phone with Navionics, but what about all the anchored boats or small craft that might also be caught in the same situation? You are blind and suddenly surrounded by a lot to hit while moving quickly!
This is where radar shines. To answer the earlier question of “Do you need radar to go cruising?” The answer is “No” because you can go cruising in places that are not plagued with fog. Head to the tropics where the water and air are both warm and fog is a rare sight to see.
We have been sailing around successfully for 5 years without a radar unit and we have done our best to avoid sailing in fog. We have had a few instances in the middle of the ocean where we came upon fog (it looks like a big grey wall in the moonlight) but it burns away as soon as the sun comes out.
One instance that radar would have been very helpful in was when we were sailing out of the Bay of Cadiz in Spain. We were anchored and a dense fog rolled in while we were preparing to sail to Morocco. We continued to prepare the boat as we waited for the fog to lift, and once it did, the world was clear and visible once more. We raised anchor and as we were sailing out of the channel, the fog came back onto us! With Navionics, I was able to overlay the AIS display on the chart on my phone’s screen; this made me feel safe sailing blind as we made our way out into the open ocean.
AIS shows me where all the boats that are transmitting AIS are located and the electronic charts show me where land, rocks, and all the buoys are located. So far, so good! But what about someone else sailing in that area who is not transmitting AIS? They would only show up on radar and I was not privy to that information.
Instead of sailing around in constant fear of crashing into an unknown vessel in the fog, I radioed the nearest commercial cargo ship (whose name I was able to get off the AIS screen) and asked if they had anything showing up on their radar that wasn’t showing up on their AIS display. The captain confirmed that everyone on his radar screen was also transmitting AIS. This meant that I could safely follow the chart on Navionics as we sailed out of the fog and into the ocean. Would I have liked to have radar in that moment? Yes. Did I need to have my own radar to sail out of that harbor? No.
Sailing in warm waters where fog is seldom seen is a nice way to avoid the need for your own personal radar, but what if you are longing to sail in high latitudes where the water temperatures are cold and any moisture in the warm air coming off the land will instantly condense into a thick cloud of fog. What are your options when it comes to radars?
Potato