AIS or Radar for a coastal cruise?

[ChrisS]

Lately I have been going back and forth on installing a radar in my 32 for a five-week cruise to Catalina and back with stops in between that I will be leaving for at the end of June. Latitude ran a piece on AIS a few months ago, and many people wrote extolling the virtues of this technology--a few said it trumps radar, although in reading around the net, many people do say the opposite.

Here are the pluses and cons for both, as I see them:

Radar pluses:
-a real time look at what's out there.
-can help with navigation.
Radar Minuses:
-power consumption
-some subjectivity in reading the screen.
-my boat has end-boom sheeting and no binnacle guard, so I'd either have to reconfigure the mainsail sheeting or put the display on a swing arm in the companionway. I singlehand in the bay a lot, so this wouldn't be a big help unless I have crew. I do have a GPS chartplotter at the helm, however, and this has helped me navigate the bay in foggy situations.


AIS receiver pluses:
-can see ships and ferries that have AIS transponders (which are most, I think).
-low power consumption.
-little learning curve in terms of reading the display.
-I have enough room to install the display unit flush on the top of the aft bridgedeck, next to the binnacle, so I can use it to dodge ships in the bay.
-the ability to hail crafts that appear on the display.
AIS receiver minuses:
- Can't see things that are there.
- Doesn't add any navigational abilities that the GPS chartplotter doesn't have.
- Greater risk of being hit by a small craft like a motor boat, another sailboat, or a fishing boat that doesn't have a transponder, which I could be able to see with a radar.

My current thinking is that I will go with the AIS, and add radar later if I find I need it, or if I decide to keep the boat for a long long time, which would then justify taking down the mast to install the dome and do a bunch of other rigging work, including moving the mainsheet forward to accommodate the display at the helm.

I thought I'd post this topic in this forum because regional weather and traffic issues, but I'm happy to get viewpoints from people who live in other venues. Thanks for your input.

 

[Loren Beach]

You have covered the arguments pretty well...

Worth emphasizing is that only radar will show you some reality in situations where your personal calibrated "Mk 1 Eyeball" is impaired, like at night or in fog.
AIS and your chartplotter are limited to showing you only what some purchased technology sez should be out there. Note that the AIS on any ship is maintained as well or as poorly as the penny-pinching ship owners take care of everything else on their rusty old income-producer.

Sidebar: the info on an electronic chart is subject to occasional errors in compilation and production, and there's always the threat of "bit rot." This was mentioned in a longer nav. thread on this site, too.
:nerd:

I love all this stuff and do use my chart plotter along with the charting application on my iBook. Budget allowing, we may add an AIS by next year. Our radar, OTOH, is the only tool on the boat other than the human eye that can show you actual reality.

Interesting topic... No wrong answers here, just differences in priority and budget.

Regards,
Loren

 

[dwigle]

Radar

We did a similar cruise a few years ago, left the bay July 11 and returned Aug. 13. Later in the summer would be better weather, but there's always a reason for timing.

We harbor hopped down and back so we spent little time in shipping lanes where AIS would be most helpful. When it was clear there was no need for radar, though it does give you an idea of how far offshore you are, especially at night. Where the radar came in most was when we were near shore, especially leaving San Simeon about 4 am in the fog. The chart plotter was great, but the radar is what really lead us out.

We also use it when the fog sets in suddenly on the bay, much more trustworthy than the GPS, especially when looking for buoys. My old chart plotter was off by a considerable amount finding the markers to the Petaluma River.

As far a mount goes, I prefer the swing arm because once we are out of the bay, I spend little time at the helm and check progress from anywhere in the cockpit with the swing arm mount for both the GPS and Radar.

Where AIS would be really helpful is in Southern CA, when going between the islands and the mainland, especially on a foggy day.

Don Wigle
Wiggle Room
E38 #8

 

[CaptDan]

Here are the pluses and cons for both, as I see them:

Radar pluses:
-a real time look at what's out there. (snip)

AIS receiver pluses:
-can see ships and ferries that have AIS transponders (which are most, I think).
-low power consumption.
-little learning curve in terms of reading the display....snip

-

Hi Chris,

The best of all worlds would incorporate an AIS-enabled radar/chartplotter - a rather pricey proposition at the moment.

Radar is no magic bullet; it takes practice to use effectively - particularly with close quarter navigation. In many ways it's like learning a musical instrument - requiring tuning and interpretation of targets. Plotter/radar combos allow you to overlay charts on radar ranges, bringing clear static navigational hazards. But moving targets can still be mis-read or over looked just the same.

AIS alerts you to the presence of large ship traffic, radio call signs, course and vessel size data; and it does the same for the big freighters if recreational are so equipped. It's a terrific safety invention but I don't think it solves all problems either. Just because an AIS signal is being sent doesn't mean either station is paying attention when it counts.

My advice would be to find a good used radar system, intall it and practice acquiring targets during nice clear days on SF Bay. Become familiar with the system's controls, constantly verifying your acquisitions against visible boats and land masses. Not only will you learn how tricky it can be, you'll get yourself up to speed before your actual cruise.

If you're singlehanding, you really should mount the receiver at the helm. That would require some 'plumbing' but it's do-able. However, I wouldn't sacrifice the convenience and safety of end-boom sheeting to accomodate this - in which case a bulkhead/swingout mount is the next best thing.

Just my opinions; others may disagree.

Capt Dan G>E35II "Kunu"

 

[ChrisS]

Thanks for the above comments--I know Radar is a more valuable tool, one that has multiple uses. I guess I have been thinking in terms of avoiding collisions with ships, when in fact I may need to think about getting into a harbor entrance in dense fog. I have learned that my GPS chartplotter is usually accurate to about 20 feet, which could make a difference in some situations. Still, if I can't figure out a way to get the display at the wheel--and I do like the end boom sheeting--I may opt for the AIS. Under autopilot, my boat is tame only when motoring, or when sailing in milder conditions, so I find I spend more time behind the helm--which I would be doing anyway going out of narrow harbor entrances.

 

[ref_123]

Radar

Well, it sure takes more time to learn, but I vote for radar or both. Radar shows ALL the stuff around such as islands, bridges, boats, buoys, etc, so it helps not only with collision avoidance but also with navigation, so if you have GPS down or have doubts in the chart (did you ever try to enter Corinthian YC using a chartplotter? ) it can be a huge asset. It also can show upcoming squalls and rain. Set up properly it can pick up a surprisingly small target - I can pick up a really small fishing boat (definitely no AIS) from a couple miles or so.

One time we were stuck outside of Fry's Harbor at Santa Cruz island in a very dense fog and were able to make our way in using radar and ears only. It's not a huge inlet, I can tell you . I always was a believer in radar but after that case I became a big believer.

Regards,
Stan

 

[Matey]

Radar -vs- AIS

Chris,

As Loren said, you have the drift. I became a believer this summer after crewing on a delivery from Richmond to Bremmerton. We had a E-120 Raymarine radar/plotter .. . It was a beautiful thing. Dealing with a tug towing a barge to the entrance at the Columbia River Bar just before daybreak in thick fog with no AIS or a hail or response on VHF. I had him clear as day on radar, figured out the deal, woke the Captain and altered course in realative comfort. Well you get the picture. The fishing boats were the other problem. Could not have delt with them unless we stuck to clear weather / daytime cruising. Being able to set up a guard zone and track targets on radar made the trip so much nicer. Not to mention entering ports we were not familiar with. I loved the system.
You could get comfortable reading radar in short order on the Bay IMHO. It's a perfect training ground with lots of targets and shore contours (most of which you are familiar with) to help in the education.

Of course its not my money.. just my biased view. Lots of folks have lots of miles with much less. I'll be helping bring this down from Washington in the fall. She'll sail with a compass, a depth sounder and a couple handheld gps/plotters and made the trip from the South Pacific in simular fashion.

As for mounting, humm ... That is a problem on our boats


Regards, Greg