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Old 09-01-2016, 04:33 PM   #41
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Great responses to my question, thanks. I have a Raymarine dome unit but don't even know the specific model. I should look into it.

Life of the unit is kind of what I was wondering about which is why I don't run it unless I feel visibility is poor. However, I agree entirely with the points that it is a good idea to run it in clear weather to get used to interpreting it.
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Old 09-01-2016, 06:12 PM   #42
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I run mine 100% of the time. As others have said, the practice is invaluable and will leave you very comfortable when the fog rolls in. Plus, ARPA is the cat's ass. Now I don't really know why a cat's ass is so great, but ARPA sure is. Lock onto a target and you can see exactly how you will pass, and adjust as needed. It takes a lot of the stress out of passing situations.

Here's a recent example. We were coming south back towards Seattle from the San Juans in very thick fog. we were out of the shipping lanes, but lined up to cross. Coming down the traffic lane was one of the big Foss tugs on an intersecting course right were we planned to cross the lanes. He was to my port, so was the give-way vessel, but.... he was in the traffic lanes and I wasn't participating, giving him priority over me crossing the lanes...

A little radar work showed that if I maintained course and speed, I would cross about 1/4 mile ahead of him. I gave him a call and after a brief pause he concurred (because he was doing the same analysis) and we both maintained course and speed. The fog lifted just as I was crossing ahead of him, and he popped out right where expected. No stress, and everyone knows what's happening. It's boating ballet.

Now in this case I was able to use AIS, but ARPA gives you all the same tracking info when the other boat doesn't have AIS. And your radar is where you are most likely going to find the tools for collision analysis.

If in 4000 hours (the life expectancy of the magnetron) I need to replace it, so what. It will have earned every penny of it's cost.
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Old 09-01-2016, 06:18 PM   #43
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I have a rather silly question. I use my radar when I feel that the viability is poor. I don't run it full time. I easily could run it full time and the information for vessel avoidance would be useful. However, I have this bad habit of not running stuff unless I need it. For radar, is there any downside to running it full time? Is there a wear and tear factor at all?
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We replaced the magnetron on our Furuno radar, ~$1,000. They have a finite life usually rated in hours according to the Furuno tech. That's one potential downside of continually running that type of radar.
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I run the radar when I leave the dock, and don't turn it off until I am tied up. I use it as practice, even during the day, to gage diatances, make sea state adjustments, EBL', etc. But, mine is solid state, and no magnetron..
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I think it is very important to run it as much as you can on bright clear days. Not only can you practice and become apt at using the various functions, it gives you a visualization of what different objects look like. This is stuff you do not want to be learning and guessing at in limited visibility situations.

We put a few thousand hours on our Furuno open array with no issues, and that is going to be more typical than the 1000 mentioned.
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Great responses to my question, thanks. I have a Raymarine dome unit but don't even know the specific model. I should look into it.

Life of the unit is kind of what I was wondering about which is why I don't run it unless I feel visibility is poor. However, I agree entirely with the points that it is a good idea to run it in clear weather to get used to interpreting it.

We've got about 1900 hours on our engines, so we've got about 1900 hours on our radar, Furuno open array, magnetron...

I too believe using it when you can see is the best time for training yourself how to use it when you really need it.

And it's also one of my easiest distance-estimators. Even in clear weather, I'm not very good at that without aid... The radar is much better at it than I am. I've often double-checked "radar distance" around here by using the plotter/charts to determine how far we are from the Bay Bridge at any given time, and then using the radar to paint the bridge for distance too.

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Old 09-01-2016, 07:04 PM   #44
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Other reasons to run radar all the time.

I get a better picture when I manually make adjustments to gain, sea clutter, etc. Those settings will change with range and sea conditions. When you need to optimize the picture in the fog or a rain storm, it needs to be instinctive, not trial an error. Use it every day and you will get very good at making these adjustments.

I'm slow. Well actually my boats are slow. Coming and going from the slip to maybe 5 miles off shore, I get passed regularly. The boats that use the slip next to my charter boat are Everglades 435s (43' center console) with 4 350 HP Yamahas (1,400 HP). Both of these boats cruise in the 40 knot range and can reach over 50 knots. At 15 knots they pass me like I'm standing still. The radar helps me keep track of boats coming up behind me so that I don't turn in front of them by accident.

I use the radar to analyse the weather I can't see. During the summer, afternoon thunder storms with lightning periodically happen. Running the range out to 36 or 48 miles let's me see the storm clouds that atmospheric conditions won't let me see.


I'm guessing I have around 5,000 hours on the original mag in my radar. The mag and the drive motor are the two wear out items in the antenna. So far so good. The original Navnets were targeted for the commercial market (charter boats, commercial fishing boats, etc) which meant continuous duty for days on end. My electronics guy said,"you'll never wear it out". For 2018 I'm considering new electronics for the charter boat. The Navnet displays are getting tired and will probably quit while the antennas just keep going. Of the 3 other radars I've had, none of the antennas ever quit; it was always the displays that died.

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Old 09-01-2016, 07:21 PM   #45
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I run mine 100% of the time. As others have said, the practice is invaluable and will leave you very comfortable when the fog rolls in. Plus, ARPA is the cat's ass. Now I don't really know why a cat's ass is so great, but ARPA sure is. .
As you know, Marpa requires manually selecting the target, and then the radar scanner requires a few rotations before it locks on.

Will your Arpa automatically grab targets, and give you their vector?

If yes, do you have to be in an automatic mode, as opposed to manual?
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Old 09-01-2016, 08:53 PM   #46
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Excellent discussion! I have an older Furano ... a 17 something or other that failed a few weeks ago just after we exited from Wood's Hole. The fog was the thickest I have been in over the last 10-15 years.

Next season I will replace the older magnetron technology with a new solid state radar. Spring is a long way off although today I am quite excited about the Raymarine Quantum. I believe it offers the best bank for my bucks even though it is a CW radar and not pulsed.

I understand how many believe that the open array magnetron radars are the cat's meow although the magnetron I believe remains yesterday's technology. The things I consider to have zero importance are far off targets that benefit from the narrow radiate beam widths (around 1.5 degrees) will not help me in collision avoidance. Sure, a 4KW peak radiated RF power pulse has much to offer for weather conditions. But so does my IPad with radar weather.

My desire is to get target info as close to my boat as possible. That desired closeness is impossible with a magnetron system that shares X band wave guide with the transmitter and receiver. A 4 or 5 degree CW low power radiated wave does not need or have the ATR (anti transmit receive) recovery time problem that a magnetron system requires which along with radiated pulse width determine the system's minimum range. A 4-5 degree beam will provide adequate target separation for my use because my only interest is for targets out to a mile or so.

I hope this thread continues thoughout the winter months for others to share their experience with the new solid state systems.

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Old 09-01-2016, 10:54 PM   #47
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Excellent discussion! I have an older Furano ... a 17 something or other that failed a few weeks ago just after we exited from Wood's Hole. The fog was the thickest I have been in over the last 10-15 years.

Next season I will replace the older magnetron technology with a new solid state radar. Spring is a long way off although today I am quite excited about the Raymarine Quantum. I believe it offers the best bank for my bucks even though it is a CW radar and not pulsed.

I understand how many believe that the open array magnetron radars are the cat's meow although the magnetron I believe remains yesterday's technology. The things I consider to have zero importance are far off targets that benefit from the narrow radiate beam widths (around 1.5 degrees) will not help me in collision avoidance. Sure, a 4KW peak radiated RF power pulse has much to offer for weather conditions. But so does my IPad with radar weather.

My desire is to get target info as close to my boat as possible. That desired closeness is impossible with a magnetron system that shares X band wave guide with the transmitter and receiver. A 4 or 5 degree CW low power radiated wave does not need or have the ATR (anti transmit receive) recovery time problem that a magnetron system requires which along with radiated pulse width determine the system's minimum range. A 4-5 degree beam will provide adequate target separation for my use because my only interest is for targets out to a mile or so.

I hope this thread continues thoughout the winter months for others to share their experience with the new solid state systems.

Foggy
One of the nice features of larger antennas and the smaller beam width is seeing separation of targets at close and distant range. While collision avoidance may only require seeing that a target exists, being able to see there is more than one target is equally important. As an example, you're coming to the inlet seabouy from off shore. You see it on the radar and you recognize it on the chart plotter. No problem passing near it as it's not going anywhere. My radar shows a boat fishing next to the buoy in the fog. Yours only showed one target which you assumed was the buoy.

You mentioned not being able to see close targets with a magnetron radar. I can still see buoys, rock jetties, and docked boats within 40' and maybe 30' of both my Navnet and my Garmin radar antennas. How much closer do you need to get? On my trawler, the limiting factor is vertical angle as the antenna is 14' off the water. The small temporary USCG buoys go under the radar at about 50' away.

Ted
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Old 09-01-2016, 11:04 PM   #48
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As you know, Marpa requires manually selecting the target, and then the radar scanner requires a few rotations before it locks on.

Will your Arpa automatically grab targets, and give you their vector?

If yes, do you have to be in an automatic mode, as opposed to manual?

Right. The "M" in MARPA stands for "mini", but it might as well stand for manual because that the most obvious difference between MARPA and ARPA - you need to manually select targets. MARPA also usually supports fewer simultaneous targets - typically about 10.

ARPA can acquire targets manually or automatically. I always do it manually, but I don't attribute it to anything other than habit/preference. I think all the Furuno radars except the wifi model are full ARPA. And I think the other usual suspect brands are all MARPA. Not 100% sure, but pretty sure for all the radars that work with MFDs. But in all honesty, I don't think the MARPA/ARPA difference really matters for pleasure cruising.

And yes, it takes a little time to get a lock on the target. Typically about a minute. This is one of the really nice features in the NXT and so-called X8 commercial radars - Internally the radar continuously tracks all targets so when/if you acquire one, you get the lock very quickly. At least that's how a Furuno rep explained it to me. On my 2117 radar which is the model before the new X8s, it gives two stages of lock on a target. An initial lock, then a full lock. I get a vector on the radar with the initial lock, but I don't get a vector on Coastal Explorer until the full lock a little bit later. I suspect the second lock has to do with when it has met the IMO specs for tracking accuracy, but I'm not sure.
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Old 09-01-2016, 11:19 PM   #49
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BTW, if anyone has a current model Raymarine or Garmin radar, I'd be real interested in working with you do some MARPA testing. It's never been clear to me how those two perform compared to Furuno and Simrad, and I'd love to collect some test examples.

The tests are real easy to run, though it will probably have to be done on a bunch of different targets over some period of time to see how consistently they perform. Give me a shout if you are willing to try it and I'll get you instructions.
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Old 09-01-2016, 11:38 PM   #50
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You mentioned not being able to see close targets with a magnetron radar. I can still see buoys, rock jetties, and docked boats within 40' and maybe 30' of both my Navnet and my Garmin radar antennas. How much closer do you need to get? On my trawler, the limiting factor is vertical angle as the antenna is 14' off the water. The small temporary USCG buoys go under the radar at about 50' away.

Ted
Good point about antenna height vs min detection distance. Most scanners have a 22-25 degree vertical beam width. So assuming it's mounted level, the beam projects 12 degrees down. If I remember my trig correctly, the distance at which the beam will hit the water surface and start picking up objects is the height/tan(12 degrees), so approximately 5 times the height. So for a 10' antenna height, the minimum distance to detecting a target at water level would be 50'. A target that stands taller would of course be detected closer in. And this is true for broadband and pulse alike.
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Old 09-02-2016, 07:37 AM   #51
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One of the nice features of larger antennas and the smaller beam width is seeing separation of targets at close and distant range. While collision avoidance may only require seeing that a target exists, being able to see there is more than one target is equally important. As an example, you're coming to the inlet seabouy from off shore. You see it on the radar and you recognize it on the chart plotter. No problem passing near it as it's not going anywhere. My radar shows a boat fishing next to the buoy in the fog. Yours only showed one target which you assumed was the Ted
Ted, the narrow beam width on a wide scanner is important for target separation, but I don't agree with your comments regarding the advantage of this system using a magnetron, over a solid state system. Again, I don't proclaim to be a radar expert, but there are various articles out there by some savvy users that show this, including screen shots of the various Solid state radars Mdf, next to a traditional output Mdfs. Check out Panbo as one example. I currently have the 4G, and have no issues with target sep.
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Old 09-02-2016, 07:41 AM   #52
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I use the radar to analyse the weather I can't see. During the summer, afternoon thunder storms with lightning periodically happen. Running the range out to 36 or 48 miles let's me see the storm clouds that atmospheric conditions won't let me see.

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My desire is to get target info as close to my boat as possible. That desired closeness is impossible with a magnetron system that shares X band wave guide with the transmitter and receiver. A 4 or 5 degree CW low power radiated wave does not need or have the ATR (anti transmit receive) recovery time problem that a magnetron system requires which along with radiated pulse width determine the system's minimum range. A 4-5 degree beam will provide adequate target separation for my use because my only interest is for targets out to a mile or so.


Yeah, I use ours for long-range weather checks, too. Some of the smartphone apps aren't too bad, but when I can see weather building off in the distance -- even some 40-50 miles away -- with the naked eye, I like to be able to check it's progress from time to time with our own radar.

When we troll, I can see our planer board off our stern quarters. Very small/low targets. For taller targets, like boats or day marks, I can usually see those very close. I think one of the tall daymarks we would routinely need to use to return to our marina in full dark and a cloudy night shows up as close as about 8 feet. Maybe I'll re-check that, this weekend...

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Old 09-02-2016, 07:53 AM   #53
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Ted, the narrow beam width on a wide scanner is important for target separation, but I don't agree with your comments regarding the advantage of this system using a magnetron, over a solid state system. Again, I don't proclaim to be a radar expert, but there are various articles out there by some savvy users that show this, including screen shots of the various Solid state radars Mdf, next to a traditional output Mdfs. Check out Panbo as one example. I currently have the 4G, and have no issues with target sep.
There are two separate points to that post. The narrow beam wide scanner paragraph had nothing to do with magnetron over solid state. The comment regarding magnetron was in regard to seeing objects close to your boat.

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Old 09-02-2016, 07:57 AM   #54
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I'll pile on in extolling a longer range capability for weather tracking. I have used this many times to great benefit. I like knowing how far it is from my location, and what our "collision" avoidance courses might be. An example is waiting another hour or so before pulling up anchor until a bad squall get's out of the way.
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Old 09-02-2016, 09:40 AM   #55
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I'll pile on in extolling a longer range capability for weather tracking. I have used this many times to great benefit. I like knowing how far it is from my location, and what our "collision" avoidance courses might be. An example is waiting another hour or so before pulling up anchor until a bad squall get's out of the way.

The available weather apps for IPads are impressive. They provide real time weather along with projections for short time future conditions.
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Old 09-02-2016, 09:43 AM   #56
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I would just like to say that most of what you guys are saying about radar has gone completely over my head. I need to go do some basic reading I guess on radar fundamentals.
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Old 09-02-2016, 09:49 AM   #57
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The available weather apps for IPads are impressive. They provide real time weather along with projections for short time future conditions.
Very true, provided you're within range for wifi, cell tower coverage, or have satellite internet. 20 miles off the coast, I have none of that.

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Old 09-02-2016, 10:04 AM   #58
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I would just like to say that most of what you guys are saying about radar has gone completely over my head. I need to go do some basic reading I guess on radar fundamentals.
Dave, you can learn a lot just anchored next to a waterway. You can watch boats come and go, play with different ranges, adjust gain sea clutter rain etc, and watch storms pass through. It's actually easier to learn when you don't have to focus on driving the boat, etc. Having a chart plotter on next to you with the same range setting will help you identify what you see on the radar and guide you through gain and sea clutter adjustments so that you can optimize targets like buoys and boats. You get proficient through use. Watching a rain storm approach and pass over you will give you an idea of what the weather is that you see on the radar. Also important to know how to tune out the rain to see other targets when traveling in bad weather.

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Old 09-02-2016, 10:44 AM   #59
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Very true, provided you're within range for wifi, cell tower coverage, or have satellite internet. 20 miles off the coast, I have none of that.

Ted
Cannot argue with that Ted
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Old 09-02-2016, 10:56 AM   #60
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I would just like to say that most of what you guys are saying about radar has gone completely over my head. I need to go do some basic reading I guess on radar fundamentals.
Kevin Monahan has a decent read, creativity named "The RADAR Book". It is oldish, maybe 10 years old, so won't have all the new fangled stuff. But it is the best instructional guide to recreational RADAR that I've read. In fact I keep a copy on the boat.
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