Radar

[svindigo]

Once you get the idea from the sources you have be sure to explore all the options on your own unit. I love the MARPA function (target tracking with CPA and TCPA projections) on ours. As said above always rely on Mk 1 vision systems. I watched a wooden fishing boat go by in broad daylight with no return on radar while I could see the 14' Boston whaler running behind it.

[KeelHaulin]

Can't understand why a radar/chartplotter would be less easy to read; it seems to me that a combi display instantly takes the "interpretation" out of the radar plot because land masses and bouys are mapped directly onto the visible chart that is underneath the scan. I've used my radar/chartplotter in both overlay and radar only and the overlay really makes the radar display "user friendly" when you have a point of reference like a shoreline or a bouy as a fixed point. Everything is displayed relative to a chart so positions of targets are "mapped" and continuously updated on that map. What could be better aside from AIS overlay or MARPA??

If I had to choose between a GPS/plotter and a radar; I might pick the plotter so I know where I am and use Mk-I to avoid other boats (while avoiding shipping lanes). But, if the radar is onboard you must have it running in low visibility; it's a COLREGS rule. Helm mounted Plotter/Radar is the way to go IMHO...

[Idiens]

From a situation awareness point of view, it is better to have chart, GPS position, radar image and AIS data all superimposed on a good display. However, if the screen fails, you've lost all systems. Separate screens for each instrument resolves that problem but at the cost of increased work load. I suppose the ideal is to have duplicated systems.

[Valiente]

Originally Posted by KeelHaulin

Can't understand why a radar/chartplotter would be less easy to read; it seems to me that a combi display instantly takes the "interpretation" out of the radar plot because land masses and bouys are mapped directly onto the visible chart that is underneath the scan.

I will clarify my own position here: I don't object to radar overlays of returns on a chartplotting screen, nor AIS inputs. What I find problematic is a single "master display" instead of separate screens, because if that display goes out, or some element of that network system goes out, you could be effectively blinded in a situation (approaching a fogbound harbour at night) that you would not attempt without these nav aids.

Having the systems stand-alone, but capable of having inputs combined on say, a PC screen, is more expensive and more space-consuming, but allows you to select your inputs as needed. In the open ocean on a wind-vane-steered course, I might have only the AIS on. At night, I would add the radar on stand-by. And so on.

I have a pilothouse with the space to have more than one display kept (one hopes) largely dry most of the time. Were I on a smaller boat and were I constantly at the outside helm, I might be persuaded that the "one display solution" made sense. But I consider it unadvisable when compared to stand-alone radar, AIS and GPS/chartplotter.

[KeelHaulin]

Yes; I agree that the drawback to a single display is that you would lose both your chart and radar if the headunit goes down. An exterior helm does not lend itself to two headunits; and a radar or chart not at the helm would make for difficulty reading unless you have a dedicated navigator.

I plan to install a second headunit at the nav station on my boat that can be run either as a repeater or independently of the main display should an emergency arise. Both make sense to have available and redundancy is a prudent choice in all situations; not just fog. For now a handheld GPS and chart for finding our position and correlating the depth is our backup for a failed plotter.

[sailaway21]

I would advocate radar far and away over the chartplotter in all cases. I'm not at all sure where this confidence in navigating by chartplotter comes from. In my opinion, if you're navigating by chartplotter in either restricted visibility or in conditions where you are unable to utilize more traditional paper charts and navigation methods, you're most likely doing something wrong.

The idea that a chartplotter is somehow of great aid in restricted visibility is pernicious and conveys a confidence that will prove ill founded. The Colregs dictate what proper procedure in restricted visibility should be and make no mention of chartplotters. Radar, on the other hand, is referenced and is a great adjunct to the human eye. And it performs the vital function of displaying targets unknown to any chartplotter, ie..other vessels.

A stand alone radar display makes sense in terms of reliability and lack of dependency on a combined unit. If you are an experienced operator of radar you'll find little need for the chart overlay. If you find the overlay of essence, I'd wager your radar skills and basic radar navigation skills need some work. As mentioned above, one of the best ways to gain valuable radar experience is in good weather. The radar display should be familiar enough that it seems like second nature to operate it.

[Valiente]

Come to think of it, when I've been navigating in restricted waters in heavy fog, I've always used a paper chart and plotted my turns using those plastic plotters the Power Squadron hands out. Basically, I send my wife forward to spot the nav aid I expect will be on station...it usually is. I only use the plotter itself for lat/lon.

I look forward to buying a radar and taking some training on it. My late father, a first mate on merchant vessels during and post-WW2, recalled when it came into the merchant fleet as a more or less widespread thing around '46 or '47 (a lot of decommissioned sets from retired warships? Maybe.) He said it made "shoulder season" runs in the North Atlantic a lot safer because they could "see" icebergs at night much more easily. He said they weren't easy to use, however, and mistakes in interpretation (we're talking 1952 at the latest here) were common.

[Idiens]

I think the principle is to use all the means at one's disposal for safe navigation. I think a chartplotter may be an improvement on hand plotting GPS positions, simply because it reduces work load, so the cycle of visual, listen, radar, AIS, depth, chart, (repeat) can occur more rapidly. All the time spent head down over the chart is time not checking the other observation means.