Radar Interpretation

[kennharriet]

I installed the Garmin HD18 Radar and have it piped into a Garmin 640s Chartplotter. I have not yet had it on the water and have not used radar before. Are there any good resources for learning how to interpret the radar signal or is it intuitive? I also have a new VHF radio with AIS connected to the chartplotter. I have not had a chance to play with overlaying the AIS targets and radar on the screen options. Any tips?

 

[rogerbum]

I installed the Garmin HD18 Radar and have it piped into a Garmin 640s Chartplotter. I have not yet had it on the water and have not used radar before. Are there any good resources for learning how to interpret the radar signal or is it intuitive? I also have a new VHF radio with AIS connected to the chartplotter. I have not had a chance to play with overlaying the AIS targets and radar on the screen options. Any tips?

I wouldn't call it intuitive. Especially with land contours in which you typically only see the leading edges of the land - e.g. solid land often looks like an island as the radar doesn't get past the first bit of it and hence doesn't reflect off the parts farther away. Also, it takes a little time to adjust the sensitivity/gain of the radar to get the best signal to noise. The best thing to do to learn how to interpret the radar is to use it on clear and sunny days. Then you can correlate the signal on the screen with what you see with your eyes.

 

[kennharriet]

Thanks Roger. I meant to say Garmin 740s. Will this type of radar also see fog or only solid objects? With the proper adjustment, will it detect a couple kayaks in the fog at say 200 yds? Will it detect a small non metallic craft without a radar reflector? I realize it is just another tool and no substitute for see and avoid.

 

[Sunbeam]

Will this type of radar also see fog or only solid objects?

I haven't used that specific radar, but have used the typical (or used to be) stand-alone radar with the green blobs on a dark screen. I was never able to see fog (although you can see solid objects *through* fog); however I was able to see heavy rain clouds (in fact, they could obscure a vessel that was "inside" them).

I really enjoyed having radar, and not only for the obvious looking for other vessels or headlands. I also found it handy at times to do things like check how "centered" I was in a crowded anchorage (I don't know about you but oftentimes by just looking outside I was "convinced" I was too close to X, only to see on the radar that no, I was as well positioned as I could be between all the objects in an anchorage), or monitor squalls to see where they were headed (and heck, in a C-Dory you could actually make some maneuvers in reaction to them ), or, while anchored, to see if I was moving in relation to fixed objects in the dark.

The idea of using it in good visibility to get used to it is a really good one. As was mentioned above, it is important to have the settings correct, or you can think you're seeing everything but not be. Also, at least with the radar I've used (this is more for other vessels than for land), I found that it was important to keep looking at it for a number of sweeps - certain vessels with less-than-ideal radar returns might not show up on one sweep, then show very faintly on the next one (making you think.... wait, was that something?), then disappear for a couple of sweeps, then reappear, etc. By watching for a number of sweeps you can let your mind and eye pick up on this type of target (that is, if the newer radar is similar to what I have used).

Sunbeam
:wants radar on the 22!:

 

[rogerbum]

Thanks Roger. I meant to say Garmin 740s. Will this type of radar also see fog or only solid objects?

Any type of radar can (in principle) "see" fog if one has the gain set way up. However, typically one doesn't set the gain up so far that you "see" fog as the most typical use is to see through the fog. What the radar sees is a combination of the radar sensitivity and gain setting and the radar reflectivity of the objects in the path of the beam. In general, you'll set things up so that you see solid objects. The more metal in those objects, the more you see. If you have the range of the radar set small (say 0.5miles) an object within that range (say 0.25 miles) will look larger on the screen than that same object when the range is set for say 8 or 15 miles. Sometimes, I'm surprised by how close something can be and show very little signal on the radar as that object has low radar reflectivity (like a small fiberglass boat). Other times, things have unexpectedly very large signals for the converse reason - e.g. high radar reflectivity (like a small boat with a radar reflector on board or a bell buoy with a radar reflector on it). Once you run a day or two in clear weather with the radar on, you'll begin to see what I mean.

 

[colobear]

I would recommend a book, "The Radar Book" by Kevin Monahan, Fine Edge publishing. It takes radar from very basic principles to lots of specifics for using radar for collision avoidance and navigation.

 

[Sunbeam]

I just looked that book up - thanks for recommending it.

Sunbeam

 

[hardee]

kennharriet,

You will find, if you follow the advice from above, that using your radar all the time, you will rapidly learn what a kayak looks like and an aluminum skiff and what the shorelines look like. You will see rain, and even birds, depending on the settings, gain, and distance are the ones I use most, and it will become your friend.

I usually like my radar clean and straight so don't often run it in overlay mode. I like the black screen with the yellow blobs. Easier to pick out what's there and not. The AIS info goes to the chart plotter and the radar is kept on it's own screen. (Actually I use a split screen set up on my display) but it is run as two separate screens. I love the AIS functions and find I use it more frequently than I thought I would. The radar is always on, ( a little matter of Colregs and collision avoidance discussed at length in some other threads.)

You will not be sorry for making those additions.

Harvey
SleepyC:moon

 

[starcrafttom]

I agree that using your radar is the fastest way to learn it. I have made a habit of always having it on and you would not believe how useful it is on the sunny days. Play with the settings and learn how to quickly adjust it for objects close and far. I have used mine to set how far a way fog it but a better use is to see whats in the fog.

Overlay is the best way, I think, to use the radar. Saves on screen space and you can see if the blob you see on screen is a channel marker or something else on the chart. I have used mine to spot kayaks, small boats and even large snags. One of the best investments on the boat.

 

[Walldog]

I have a Garmin 18D also. I usually run with it on as other posters recommended. Yesterday was a great day to use it crossing our bay. There was the Pirate Ship, a couple of head boats ($20 head for fishing), an Eco Tour boat, a boat pulling a parachute. and several fishing boats. All going different directions in a limited space. Non with AIS. I acquire the targets, so I can see direction and speed of travel using the Overlay screen which I have primary with a small Nav screen and engine monitor screen filling up my 5212 display. I know I could have threaded my way through without the radar, but the practice sharpens my skills for when visibility drops to nil. And it does add a measure of safety in good visibility. If I had a smaller screen, my choice would be the radar overlay as a primary display. Congratulations on your new radar. As you learn to use it, you will find it to be an invaluable tool.

 

[Gene Morris]

Sunbeam;

I also have the HD18 hooked to a Garmin 3210. My old radar was the Garmin 41. The new 18hd is fantastic and much more sensitive than the older one. Our bay has some shallow channels marked with PVC pipes The new radar will pick up each pipe seperately and will also pick up flying/diving birds when salmon or tuna fishing. Like said above it is best to work with your radar in good visibiliity you will see that the radar doesn't lie to you and you will get used to the targets and what they mean.

Gene

 

[matt_unique]

I find many aspects intuitive when you turn it on, but learning the nuances of your system takes time. You should always have it on during the day and in good weather to learn those nuances. Plus, when is it bad to have a pair of electronic eyes during the day? In busy ports I love it.

One of the things you will learn and perhaps be surprised with is how small a signal some vessels provide. I do not regret my trilens radar reflector for a minute and have tested it in pea soup fog.

One thing that is very important is to adjust your newly installed radar such that items dead ahead show up on your screen as dead ahead. You will most likely need to adjust this a few degrees. Test this carefully on a calm day with a stationary object offering a big return.

What a great safety tool to have aboard. My longest cruise 'under the hood' in thick fog was 30 nm. It was a beautiful thing to see through the fog and enjoy the flat calm seas with no wind.

 

[kennharriet]

Thanks all for the education. I really appreciate the benefit of your collective wisdom and experience.

The catalyst for getting radar was from an event last spring. We were at Princess Louisa on our first major boat adventure and got word of a family emergency. We needed to get back to the truck in Bellingham and travel to CA asap. We encountered fog on the return trip which delayed our egress. I was tempted to push the fog because of the urgency of the situation. We also had a minor mechanical problem with a stuck thermostat. This kept us in Friday Harbor overnight and prevented me from pushing the fog until it lifted.

Even with the new tools we do not intend to get into situations where it is essential, but it will be nice to reduce risk if we have to in the future. I look forward to learning more about radar use. Where else can one find a hobby where your spouse asks you to buy another toy (I mean tool). "OK dear, if you really think it's necessary".

Thank, Ken

 

[SENSEI]

If memory serves me right, I remember a good tutorial was posted here quite a while ago by Dusty about radar usage. I have looked for it to no avail. maybe someone can find it for us.

 

[colobear]

Ken,
Your post aptly illustrates Dreamer's wise maxim "The most dangerous thing on a cruising boat is a schedule". You made a good choice to wait and arrive. Having soapboxed, radar is an indispensable tool for us. We have it on all the time except when we are in a marina or next to another vessel. Many time I have picked up a vessel on radar and then looked around to find it just out of my normal vision arc. It is particularly useful for seeing vessels approaching from behind and...official rules in the collision regs. require you, if you have radar, to have the it on when underway. I have avoided being hit in a t-bone collision in fog when my radar warned of an idiot going 20+ Kts in dense fog. I made a sharp turn and he roared through never even knew we were there! I prefer to use it in overlay mode and it really helps me steer a straight course in fog.

 

[Sunbeam]

...official rules in the collision regs. require you, if you have radar, to have the it on when underway.

Although I think radar is a wonderful tool, and there is nothing at all wrong with having it on, say, a clear, sunny day with 10-mile visibility, it is not required indiscriminately, as I understand the regulations.

Here is an excerpt:

RULE 5 Look-out
Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.

Emboldening is mine.

The way I was taught this rule is that the section I emboldened does apply. That is, if you have radar and the prevailing circumstances and conditions mean that it's something you should have on, then yes, it is part of keeping a proper lookout, and keeping a proper lookout is required. Thus in that circumstance the radar would be required.

However, in the example I used above, of a clear, sunny day with 10-mile visibility, then, the way I learned it, radar would not be required in order to keep a proper lookout. Thus it would not be required.

Not that there is anything wrong with using it to practice (in fact, I think it's a good thing), nor is there anything wrong with having it on just because you feel like it. And certainly if conditions are marginal, the rules infer that one should err on the side of "proper lookout" (i.e. use the radar).

Sunbeam :hot

 

[journey on]

The only way I've found for learning to use the radar is to use it when you don't need it. Saying that, operating the radar (at least the ones I've used,) isn't easy so keep the manual handy.

Also, let me stress after you've learned to use it by comparing visual scenes with what's on the radar, keep using it for practice. I relearned this in So Cal fog a couple of months ago, when I nearly pronged a boat because I hadn't adjusted the radar for the prevailing conditions: smooth water and going at 12 knts. Luck beats skill, again. So learning and keeping in practice are two complementary skills, practice being more important in the long run.

Also, on the manual's cover, I make my own index of what I think important.

Radar is wonderful, but it's a skill that needs to be learned and maintained.

Boris

 

[colobear]

Your quote is from, I think, Navigation Rules Part B Steering and Sailing Rules, Section 1-Conduct of Vessels in any Condition of Visibility, Rule 5 Look-out.
If you go a little further to rule 7 Risk of Collision, (b) you see: "Proper use shall be made of radar equipment if fitted and operational, including long range scanning to obtain early warning of risk of collision and radar plotting or equivalent systematic observation of detected objects."

The Colregs 1972 edition which is afik the latest; says:
"5. Look-out
Every vessel must at all times maintain a proper look-out by sight (day shape or lights by eyes or visual aids) and hearing (sound signal or Marine VHF radio) as well as by all available means (My bold) (e.g., Radar, Automatic Radar Plotting Aid (ARPA), Automatic Identification System (AIS), GMDSS...) in order to make a full assessment of the situation and risk of collision."

I'm not interested in getting into a contest here but as far as I know if you have a collision and your vessel is equipped with a working radar; and if you were not "standing a radar watch" you are automatically in violation of rule 5 above and at least partially liable/at fault.

 

[thataway]

A little pricer at about $140 (you may find it used) is Starpath Radar trainer for the computer. It is highly recommended.

Agree that using it is the best way to learn on clear days.

You should be able to pick up Kayaks with that radar. You will pickup rain squalls and approaching weather fronts.

I recommend tuning the radar manually, not using the auto magic mode. Look at Gain, Sea Clutter rain clutter etc. Learn what ghost images look like--and what is "real".

Never travel faster than you can stop in time to avoid a collision. I don't run that fast in fog, or at night (unless very clear and on other boats around) It just makes traveling at 6 knots safer--not allowing you to trail at 25 knots.

You may need a heading sensor for overlay. I personally prefer it on its own screen.

The AIS is easy, be sure you have the right com port, and baud rate set. Then go to the menu. I have really enjoyed the Garmin AIS thru the Standard Horizon radio. Picks up all of the targets. Some times it seems like too many! But that is all safety. This is also one of the reasons we run two GPS platters. One is only GpS--no sounder, no AIS, no radar etc.

 

[Sunbeam]

I'm not interested in getting into a contest here

Me neither.

...but as far as I know if you have a collision and your vessel is equipped with a working radar; and if you were not "standing a radar watch" you are automatically in violation of rule 5 above and at least partially liable/at fault.

My understanding is that one is not required to "stand a radar watch" in times of good visibility (it is optional of course). One IS required to keep a proper lookout. But, I'm comfortable with "agreeing to disagree."

**********

One nice thing about a powerboat is that you do have the ability to run the radar anytime you are underway, with no real "penalty." So it's an easy choice.

When sailing, for example, it's not always possible. Amp hours are precious, and fuel and other means of recharging are limited. That doesn't mean that one doesn't keep a proper lookout, including running the radar when it is prudent. But if under sail for long periods of time one doesn't typically run the radar constantly during periods of clear weather and good visibility, but rather keeps an eyeball/binoculars/etc. lookout. I don't believe this is contrary to the rules, but I see this is where we differ. I'm fine with that as anyone who reads this thread can do research for themselves.

Sunbeam