Radar??? Yes/Maybe/No?? Advice?

[southofvictor]

Don’t forget that radar has many navigational benefits besides collision avoidance in fog, especially at night.

I prefer running split side by side screens on the plotter (chart/radar) rather than the overlay because it gives more dimension to the overall picture and I can change radar ranges without changing chart scale.

Sounds like you’re making a well informed choice. Good luck with the implementation!

 

[Akavishon]

Can anyone comment on the practical power requirements/consumption of modern electronics, especially radar?
I still imagine radar to be a power hog, has newer technology transcended the old image?
TIA, Zoran

 

[wynkoop]

Can anyone comment on the practical power requirements/consumption of modern electronics, especially radar?
I still imagine radar to be a power hog, has newer technology transcended the old image?
TIA, Zoran

Modern radar equipment ranges from 1.5 KW to over 50 KW in power. Most radar on recreational vessels in in the 1.5 - 3 KW range.

Using Ohm's law a 3KW radar will require 250 Amps peak. Of course the duty cycle is not 100% so the effective draw will be less, but radar is a big power hog. On the other hand GPS and chart plotters can require as little power as a tablet computer. I run OpenCPN as a chart plotter on my cell phone, purpose built chart plotters will not pull much more than a few amps.

This 4KW radar claims a 38 watt draw.

8.4" COLOR LCD RADAR MODEL1815 | Marine Radar | Products | FURUNO

www.furuno.com

That is of course average. You still have to be able to supply the peak power for the transmit cycle, so make sure use good wiring practice and the right gauge wire as specified. Perhaps consider hiring a licensed tech to evaluate your situation and do the install.

 

[Teranodon]

Thanks Stefan. This helped me as we hone in on which model we get.

Here's what the chartplotter screen looks like with the Garmin Fantom doppler radar. The big red blob is an approaching Washington state ferry. The two smaller green blobs are boats that are moving away. Everything else in black is "stationary" (note that the software is aware of the GPS speed so it corrects for that: approaching land is not considered as moving). AIS targets (identified by the Garmin VHF radio on the network) are shown as green triangles.

 

[Akavishon]

Modern radar equipment ranges from 1.5 KW to over 50 KW in power. Most radar on recreational vessels in in the 1.5 - 3 KW range.

Thank you - very helpful info. So, sailing for several hours with radar really means motor-sailing? Or one needs a separate generator on board?

 

[Loren Beach]

Thank you - very helpful info. So, sailing for several hours with radar really means motor-sailing? Or one needs a separate generator on board?

We have owned three brands of radar units on our boat over the decades, and since we are normally motoring when using radar have never noticed any draw down of the battery bank. Modern (digital) radars do not seem to need much power compared to the ones from the 70's and 80's. Consider these musings as anecdotal evidence, at best, tho.

Edit: I just checked the spec's for the current Simrad Halo20 (smaller boat product, like our present one) radar.

Electrical Power Consumption: max20W
Power Consumption: typical18W
Recommended Fuse Rating: 5A
Supply Voltage10.5 - 31.2 VDC (12/24V systems)

 

[wynkoop]

Thank you - very helpful info. So, sailing for several hours with radar really means motor-sailing? Or one needs a separate generator on board?

I suppose it depends on the battery bank on your boat. On my 27 with a pair of group 24 batteries I would keep the motor running, even at less than 5A draw. On my friends 38 foot Ketch with a bank of 4 4D batteries (total AH around 800) I would not worry about the battery drain over a few hours, especially since there is an independent starting battery.

 

[Christian Williams]

If you have two G24s and 75 amp hours rating, wouldn't that be fine for a few hours of radar? You could go down to 50 percent charge before turning on the engine, right?

 

[wynkoop]

I never tie my batteries together unless I have to for starting on a very cold day, or for charging when the engine is running.

When operating under sail or sitting where I do not have shore power I use one group 24 for my house needs. In that situation let us say you are running the following under sail in the fog:

Low Power Radar - 3A
VHF - 2A (average estimate- high power tx will be about 5A and rx probably 1/2 A squelched)
GPS - 2A
AIS - 2A (assuming class B tx capable)
Running lights 3A - you may be lower if you are all LED. I am still using my bulb that were in there when I bought the boat in 1984
Misc cabin lights 3A

Total =====> 15A

So assuming you are fully charged 3 hours would be 45 AH. 75 - 45 = 30 AH (30 / 75)100 = 40% charge left after 3 hours.

This is of course a very rough estimate based on assumptions about what you will be running and the current draw of those devices. Also remember we consider a "12 volt" lead acid battery fully discharged at 10 volts, and we never want to get to that point if we want best life. I try to not let mine go below 11.5 V. The real way to figure if you have discharged as low as you should go is to keep an eye on the voltage. I have a digital voltmeter in my panel.

When my "house" battery gets to 11.5 V if I am away from shore power I will switch to the number 2 battery, start the engine and advance the throttle until the alternator kicks in. Then back it down to idle and the alternator keeps charging. I leave the 2 batteries joined so that the low battery gets filled back up and the battery that just started the engine gets that energy put back.

I do have 2 small solar panels, a 5 watt and an 8 watt, one connected to each battery, so daysailing on a sunny day the batteries actually charge and keep up with the draw of the VHF on mostly RX.

So my advice is add up your current consumption for everything you will be running in the fog or at night and use that to estimate how long you can run, but keep an eye on the voltage. I have ruined a few batteries by over discharge due to forgetting a cabin light when I left the boat.

2021 gadgets are great, but always be ready to operate as if you are in 1865. That is why I have an oil lamp in my cabin! I would love to have some oil running lights! Perhaps one day!

 

[peaman]

I installed all new B&G electronics, including radar two years ago. My minimum power usage with radar is 2.6A. If I change my MFD display to chart, the radar will automatically go to standby, reducing power usage to only 1.5A. The following instruments are powered in my minimum power configuration:
B&G 7" Zeus3 MFD; B&G HALO 20 (without the "+") radome; B&G WS310 wind instrument; B&G DST810 depth and speed instrument; 2x B&G Triton2 displays, both on "sleep" mode.

I have a Victron BMV-712 battery monitor which has been very useful in checking the battery draw for each individual instrument and circuit, simply by switching things on one-at-a-time. The following lists the relevant loads in my 32-3:

Original incandescent cabin dome lights: 9 lamps total 9.3A
Incandescent deck-level running lights: 1.8A
LED mast-top tri-color running light: 0.46A
LED steaming light: 0.23A
LED anchor light: 0.47A
LED foredeck light: 0.46A
Instrument circuit (2x Triton2 displays with WS310 and DST810): 0.54A
Instrument circuit (incl. 0.54A above) with B&G Zeus3 7" MFD chart plotter: 1.75A total
Raymarine Wheel Pilot on "standby": 0.27A
Standard Horizon VHF with AIS receiver and antenna coupler: 0.76A
Vesper Watchmate 8000 AIS transceiver and antenna coupler: 0.43A
Antenna coupler only: 0.13A
Refrigeration with compressor running (intermittent and varies, depending on load): 5.6A
Refrigeration with compressor off: 0.12A
Propane solenoid: 0.95A

 

[Christian Williams]

Very interesting. Your draw is pretty much same as mine. Offshore I use about 20 amps a day, which includes only an hour of refrigerator. Locally with frig on all the time (just maintaining 50F) more like 30 amps/day on the Victron.

Under sail I'd have to be judicious about radar use, and if seeing consecutive days of heavy fog would have to run the 100-amp alternator for an hour periodically, maybe twice a day.

 

[Prairie Schooner]

I installed all new B&G electronics, including radar two years ago. My minimum power usage with radar is 2.6A. If I change my MFD display to chart, the radar will automatically go to standby, reducing power usage to only 1.5A. The following instruments are powered in my minimum power configuration:
B&G 7" Zeus3 MFD; B&G HALO 20 (without the "+") radome; B&G WS310 wind instrument; B&G DST810 depth and speed instrument; 2x B&G Triton2 displays, both on "sleep" mode.

I have a Victron BMV-712 battery monitor which has been very useful in checking the battery draw for each individual instrument and circuit, simply by switching things on one-at-a-time. The following lists the relevant loads in my 32-3:

Original incandescent cabin dome lights: 9 lamps total 9.3A
Incandescent deck-level running lights: 1.8A
LED mast-top tri-color running light: 0.46A
LED steaming light: 0.23A
LED anchor light: 0.47A
LED foredeck light: 0.46A
Instrument circuit (2x Triton2 displays with WS310 and DST810): 0.54A
Instrument circuit (incl. 0.54A above) with B&G Zeus3 7" MFD chart plotter: 1.75A total
Raymarine Wheel Pilot on "standby": 0.27A
Standard Horizon VHF with AIS receiver and antenna coupler: 0.76A
Vesper Watchmate 8000 AIS transceiver and antenna coupler: 0.43A
Antenna coupler only: 0.13A
Refrigeration with compressor running (intermittent and varies, depending on load): 5.6A
Refrigeration with compressor off: 0.12A
Propane solenoid: 0.95A

This is super helpful. Very similar to what we'll have, except 9" display and no fridge. You have some things on this list I never would have thought of. Thanks!! Which model of radar scanner did you get? We're trying to decide between the HALO20 and HALO20+.

 

[Prairie Schooner]

The first step was for the techs to be sure they could run the wire through the mast without unstepping it. They did that today. Whew, major expense dodged. We get hauled tomorrow and they can't go back up the mast now until the boat's back in the water. We have some time to decide on the scanner to purchase.

 

[peaman]

Which model of radar scanner did you get? We're trying to decide between the HALO20 and HALO20+.

As I understood it, the HALO 20+ is not compatible with the 7" display, but I think that it is for the 9" and larger. I have used radar on other larger boats over the years, but have used my present one only once where I could evaluate it and I emphasize that I was very impressed with it in close-distance reception. My dome is on a Scanstrut backstay mast, maybe 14 feet above the water, in an arrangement I am happy with.

Since HALO+ was not available to me, I didn't look into it before purchase, and with a quick look now at the differences, I don't feel like I'm missing out on much. The "not+" has both "harbor" and "offshore" modes. I wonder if a user will perceive the difference between the claimed range of 36 miles versus 24. I know the HALO + has a cool looking blue LED on the bottom of the dome, but I wonder if that's a good thing or not.

Good luck in your shopping, and let me know if I can help further. I and my boat are in Mystic/Westerly area if you'd like to drop in and see what I have. etc.

 

[p.gazibara]

Perhaps I can weigh in. I worked for Navico doing software testing on the latest and greatest. The Halo radars are very easy to install and pulse compression is relatively battery friendly. I believe they have sweep and sleep running on the NOS MFDs but not yet for the android models (I would verify that). The radar can also share to all your MFDs if they are networked.

We don’t have radar, and I probably wouldn’t put one on Cinderella even if they gave me one, she’s just too small for that windage. I’m a KISS follower and our VHF does the fog signals for us.

The radars can run two ranges at the same time so you can monitor for vessels up close and weather in the distance or whatever you want to.

I can tell you that with bird+ mode we could see birds dive bombing the water from 10nm out.

I also tracked foiling windsurfers going around the buoys in a race from the work boat. It managed to track the dozen small targets well reporting both speed and heading accurately.

I don’t work there any longer, but the guys there invented the pulse compression radar and they are a good crew.

The beam width is about 15 degrees, so heeled you will see degradation in your returns unless you gimbal the radar.

-p

 

[Teranodon]

The beam width is about 15 degrees, so heeled you will see degradation in your returns unless you gimbal the radar.

This brings up another radar controversy: to gimbal or not? I went through the arguments when I was facing this circa $1000 question. I chose not.

 

[Prairie Schooner]

This brings up another radar controversy: to gimbal or not? I went through the arguments when I was facing this circa $1000 question. I chose not.

Someone said earlier in this thread that in times of low visibility you're less likely to be carrying lots of sail. That rings true for our likely possibilities. We're juggling the odds/downside severity/cost equations as we go and have decided to use the existing stationary mast mount. If we were racing in low vis, we might opt for the gimbal.

 

[Prairie Schooner]

. . .
And then, before any of those concerns come into focus, you first have to decide on mounting and which models have a chip door with a permanent magnet that will disrupt your steering compass (minimum of 19" to over 30" away depending on model/brand). That was the reason we chose the Lowrance over a very similar Simrad, last time around.
. . .

Loren, You've mentioned this before and it's had me very concerned. I did some crude experiments. Video seemed the best way to present them so I put this together. I'd be really interested in whether you or anyone else see major holes in my methods.

(I couldn't resist the urge to get a little artsy at the end, but the production value is really hack, especially compared to what some of the rest of you have done. Sorry about that. Improving those skills is one rabbit hole I don't have time for right now.)

Jeff

 

[Loren Beach]

Jeff,
Your "real world" test is kind of similar to what our local shop advised me to try. Seeing some slight (but reproducible) deflection, I opted out of the two models that I tried with their magnetic doors, and went with the model with the friction catch door. No compass movement observed with the chosen model.
My reasoning was that, from reading up on compass behavior, magnetic interference varies with the tilt of the card, and therefore the position of the needle inside. Since I had the option of no magnet vs magnet, I could opt for the one with least chance of interference. As you point out, local cruising does not make the use of the ship's compass absolutely vital anyway. (My words, not yours.) Being recreational boaters, 99% of the time we can opt to stay in port if visibility is below our own "worry threshold"...

Further, to flog the mostly-dead magnetic horse, those warnings buried deeply in the install manual for these devices are first based on their lab testing and then very likely modified at the behest of their liability lawyers. An admittedly cynical guess is that the marketers were equally involved and the stated number of inches distance from a compass was shaved down to less than optimal. Whatever 'optimal' means.
After all, they do have to plan for a possible legal action from your surviving relatives after their device "may" have caused your death against a rip rap jetty on a moonless night. And, they have more money to spend on billable hours by a factor of 100X, than us boaters can muster.

Thanks again, and your test echos what I have sometimes contemplated trying to do.

 

[peaman]

Well done, Jeff. I raised this same concern a while back. After careful consideration, I installed my 7" MFD a bit higher than you are planning, and I have no concerns about the affect on the magnetic compass. I would have liked for it to be lower, but this seemed to be at a prudent distance from the compass. If I needed better accuracy than +/- several degrees, I will use my hand-bearing compass. I also have use of the fluxgate compass connected with my wheel pilot.