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Old 09-09-2021, 01:28   #31
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Re: Wind Instrument

The CV7 can be linked to a multitude of different output boxes N2000 and NMEA183 being but just two. If the unit itself is fine it should be possible to re-connect the cable and lead down the mast and add the desired NMEA unit below deck.

Beware extra long "racing" mast head wind units, great for accuracy but not super robust, my extra long (very expensive) mechanical unit shook itself to bits on an Indian Ocean crossing the added inertia was just too much for it. It got it replaced with a CV7 in Mauritius and I have to say it is by far the most accurate I have experienced and LCJ support is excellent.
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Old 09-09-2021, 01:43   #32
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Re: Wind Instrument

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Originally Posted by Tupaia View Post
The CV7 can be linked to a multitude of different output boxes N2000 and NMEA183 being but just two. If the unit itself is fine it should be possible to re-connect the cable and lead down the mast and add the desired NMEA unit below deck.

Beware extra long "racing" mast head wind units, great for accuracy but not super robust, my extra long (very expensive) mechanical unit shook itself to bits on an Indian Ocean crossing the added inertia was just too much for it. It got it replaced with a CV7 in Mauritius and I have to say it is by far the most accurate I have experienced and LCJ support is excellent.
That's interesting - a B&G racing unit or what kind.
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Old 09-09-2021, 02:31   #33
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Re: Wind Instrument

As mentioned earlier, I run a 0183 indicator on the mast that feeds the N2K network via an ITC5 converter behind the nav station.

The ITC5 can fail, of course—but then all I lose is wind. No biggie.
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Old 09-09-2021, 03:51   #34
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Re: Wind Instrument

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How do you do that when you're alone on deck in a gale (or single handed) and the failure has brought the whole network down including the pilot?
Sorry about your finger. Any type of troubleshooting in these situations is going to be very difficult, if not impossible. On a forum people will talk of heaving to and simply repairing the issue as if they were in a marina, but the reality of fault finding in offshore conditions is very different.

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If I had run the 0183 cable down the mast as the maker intended, I would have only lost the wind instrument instead of the whole network.
You are suggesting that on a NMEA 0183 system if one component is faulty the system is less likely to disable all instruments than on a NMEA 2000 system. While the NMEA 0183 system works on a star wiring configuration rather than the series wiring configuration of NMEA 2000, I am not sure this accurate. Perhaps some of the marine professionals dealing with these systems daily can comment.

The most likely fault in a NMEA 2000 system that would bring down the whole network would be a short in power supply component of the NMEA backbone, which I understand is the problem you experienced. The same fault on a NMEA 0183 system would also disable the whole system unless you have a separate power supply for each device. The NMEA 2000 system can also be installed with a separate fused power supply for different sections of the backbone and this is an option that is worthwhile.

The other, and more common fault, is a failure on the data side. The most common defect is for a faulty instrument to stop sending data. On both systems this would simply disable the defective instrument. Sometimes a defective instrument will start transmitting multiple defective messages. In this situation the better data rejection and higher bandwidth inherent on the NMEA 2000 network is less likely to crash the whole system.

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Yet another reason not to extend your N2K network up the mast -- it is not so easy to even find the fault in an N2K network when all the devices are theoretically working. It took me two days of hard grafting at sea, in rough sea conditions, to finally figure it out.
You have my sympathy, tracing intermittent electrical faults can be a nightmare especially at sea. I am not going to mention the time I caused a crash gybe by turning off the NMEA network breaker to try and find a fault, forgetting that the autopilot needed the network for heading information

However, I would suggest a NMEA 2000 network is much easier to troubleshoot than a NMEA 0183 network. On a NMEA 2000 system all the components can be isolated by simply unplugging the connector. This also applies to the backbone, although in this case you need to screw in a termination resistor in place of the removed section of cable.

In summary, I have installed both NMEA 0183 and NMEA 2000 systems on various boats and personally, while slightly better, I don't think the 2000 system is the revolutionary improvement most claim. Both systems can be reliable and the NMEA 0183 system is not difficult to install if you follow a few basic rules. However, I would suggest that combining these two systems with NMEA 0183 and NMEA 2000 components is something better avoided in an ideal world.
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Old 09-09-2021, 04:05   #35
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Re: Wind Instrument

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Originally Posted by noelex 77 View Post
. . . You are suggesting that on a NMEA 0183 system if one component is faulty the system is less likely to disable all instruments than on a NMEA 2000 system. While the NMEA 0183 system works on a star wiring configuration rather than the series wiring configuration of NMEA 2000, I am not sure this accurate. Perhaps some of the marine professionals dealing with these systems daily can comment.. . .
To be clear, I'm not at all arguing for 0183 networks over N2K networks. I like N2K and I don't miss my previous 0183 networks. This is particularly true when you have more than three or four devices to connect. I have more than 20 devices on my N2K network; ajlmost no way in the the world to do that with 0183.

What I am arguing for is different -- not extending the N2K network endless into places you can't reach and into places where there is inherent risk of pinching something or bashing it into a short circuit situation. That's all. If you connect your wind instrument some other way -- not necessarily 0183, but could just as well be the B&G pulse wire, or whatever -- and terminate the N2K network 23 meters closer to the other end of it, you have a lot less risk of bringing the whole network down with a fault.

I think it's simpy better network architecture.

If you for some reason still really wanted N2K up the mast, you might be well served to make that a separate network with its own power supply, and use a Maretron network joiner (I actually have one of these).

And now that I think about it, since I do have the joiner and second power supply, maybe I'll split my network to make it a bit more fault resistant. Hmm. I could split it between forward and aft, and so everything affecting the pilot will be on the smaller forward section. I'll have one compass on each half since I have redundant compasses. I'll have pilot controllers on both halves since both my plotters have built in pilot controllers. What a good idea you've given me.

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. . . However, I would suggest a NMEA 2000 network is much easier to troubleshoot than a NMEA 0183 network. On a NMEA 2000 system all the components can be isolated by simply unplugging the connector. This also applies to the backbone, although in this case you need to screw in a termination resistor in place of the removed section of cable.
Completely agree. Actually it's even better than that -- you have powerful tools in N2K you don't have with 0183 -- device list, access to raw data from all devices in a single page, network diagnostics. I do think N2K is a pretty big advance.

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.In summary, I have installed both NMEA 0183 and NMEA 2000 systems on various boats and personally, while slightly better, I don't think the 2000 system is the revolutionary improvement most claim. Both systems can be reliable and the NMEA 0183 system is not difficult to install if you follow a few basic rules. However, I would suggest that combining these two systems with NMEA 0183 and NMEA 2000 components is something better avoided in an ideal world.
Here I disagree. I don't see any harm in using isolated 0183 devices on an N2K network. Most people do it. Downside compared to native N2K is you can't get at the device itself via the network for calibration or diagnostics, but upside is more fault tolerant.

What concerns the CV7, it's not 0183 which is the point -- it could be a proprietary protocol like B&G. Look at the CV7 with Windy Plug as a single device, just it's split into two pieces of hardware with a cable in between, not important what protocol is being used over that cable.

Note that many high end racing sensors of different type are not native N2K and intentionally not. Until just this year I was using an Airmar ultrasonic speed log which outputs proprietary pulse data. This is converted to 0183 with an Actisense DST box, which I then connected to the 0183 listener of one of my plotters. Works fine; the plotter shows up as the source of STW data in the N2K network. When my native N2K depth sounder blew up, I replaced it with an old fashioned pulse one and hooked that up to the same Actisense box. These transducers are simpler and I guess more reliable than the native N2K ones so might be a better solution altogether.



In ideal world you might really not want to connect transducers directly to the network. A box like the B&G H5000 might be a better solution. One of my disappointments with N2K is that you can't really calibrate anything with it. Fewer nodes on the network will make it more robust.
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Old 09-09-2021, 04:17   #36
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Re: Wind Instrument

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Originally Posted by C420sailor View Post
As mentioned earlier, I run a 0183 indicator on the mast that feeds the N2K network via an ITC5 converter behind the nav station.

The ITC5 can fail, of course—but then all I lose is wind. No biggie.
This depends on the nature of the fault. A short on the power side of the ITC5 would disable the whole NMEA 2000 network (unless you have a divided power supply). The effects of a fault on the data side will depend on the nature of the fault. In most, but not all cases this would only disable the wind instrument. All the above is also true for a pure NMEA 2000 network without the ITC5. I am struggling to see any practical difference other than the ITC5 introduces another complex piece of electronics, and user reports suggest these protocol conversion devices are not particularly reliable.
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Old 09-09-2021, 04:44   #37
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Re: Wind Instrument

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Originally Posted by Dockhead View Post
And now that I think about it, since I do have the joiner and second power supply, maybe I'll split my network to make it a bit more fault resistant. Hmm. I could split it between forward and aft, and so everything affecting the pilot will be on the smaller forward section. I'll have one compass on each half since I have redundant compasses. I'll have pilot controllers on both halves since both my plotters have built in pilot controllers. What a good idea you've given me.
This is exactly what I have done using the Actisense box I linked in the previous post. The Actisense box is not essential to implement this wiring redundancy, but it is a neat solution and also has a couple of useful diagnostic LEDs. Two LEDs indicate if there is network data on each of the legs of the backbone and another two show if the fuse has blown supplying power to the two independent legs of the backbone.
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Old 09-09-2021, 06:54   #38
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Re: Wind Instrument

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How do you do that when you're alone on deck in a gale (or single handed) and the failure has brought the whole network down including the pilot?
Doesn't your boat heave-to?
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Old 09-09-2021, 07:03   #39
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Re: Wind Instrument

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Doesn't your boat heave-to?

Absolutely. But so what? It took me two days to figure out the problem. Heaving to would not have helped.
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Old 09-09-2021, 08:02   #40
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Re: Wind Instrument

What is everyone using for system diagnostics? We like and use the Maretron USB gateway but also use an Actisense gateway to look at our network. They both have advantages and disadvantages but they do give the operator a better look at the system as a whole.
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Old 09-09-2021, 08:03   #41
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Re: Wind Instrument

Your comments about the reliability of the NMEA2000 bus are very interesting.
Some time ago, a navigator and aviation pilot made a comment on this matter, referring to the fact that in aviation, all systems are double and redundant.

If we look back a few years, the merger between Robertson and Simrad produced a generation of "transitional" pilots. These pilots had analog connections for the fluxgate, received the information through NMEA0183, and used a local Robnet2 bus for the pilot and keypad environment. Only the display / keypad unit also connected to NMEA2000 / Simnet.
A similar case occurred with the old STxxxx with Seatalk, but in this case, the keypad used the same Seatalk bus as the rest of the instruments (AIS did not yet exist, and only the GPS constellation was in use).

Unfortunately, all manufacturers today blindly trust the NMEA2000 bus as the only bus on board. Vital data for navigation (Heading and Control keypad) pass through it, and at the same time, very "talkative" devices such as AIS and GNSS are connected. (Even stereos !!!)

I think it would be interesting to develop an N2k dual bus bridge that electrically isolates vital sections from those that are not, and at the same time, establishes a filtering to prevent saturation with useless data for the pilot. This device could have the resistive terminators at each end of the two networks.
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Old 09-09-2021, 08:24   #42
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Re: Wind Instrument

A network with a bus topology such as N2k, has already been discarded for use in local networks for this reason "Everything is absolutely heard by everyone". In addition, a cut or a failure in a "T" connector could easily cause the entire network to drop because the resistive loads at the ends were disconnected. These charges avoid reflections and are important.

The bridge that I propose would be something similar to a "Switch + Router" in the Internet network environment, but with CAN BUS.

How do you see this idea? Do you know if it already exists?
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Old 09-09-2021, 08:33   #43
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Re: Wind Instrument

In your original post you asked for advice. Here are my thoughts:
1) Sailing at night without a compass light sounds like a really bad idea.

2) Heaving to would have given you time to wake up your crew to help with hand steering and given you time to figure out what's wrong.
3) I don't know how many devices you have on your N2K bus, but it shouldn't take 2 days to figure out the problem by disconnecting them one by one. I assume you have a multi meter on board. If you don't, you should get one.
4) A red LED flashlight, or even better, a red head lamp in the cockpit can come in very useful in a situation like this.

5) Your N2K instrument network went down due to a masthead short, but electrical problems can happen with any network. N2K is based on DeviceNet, a very reliable standard for industrial applications. NMEA0183 can short out just as easily. Your autopilot could go out for other reasons too (they are notorious for being unreliable and many people carry complete spares.) So you need to think through a contingency plan for a situation like this.
6) If you are not racing, the ultimate accuracy in a wind instrument is probably not terribly useful. When looking for a replacement, focus on reliability instead. As a rule, with each component you add potential points of failure and decreased reliability.
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Old 09-09-2021, 08:59   #44
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Re: Wind Instrument

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5) Your N2K instrument network went down due to a masthead short, but electrical problems can happen with any network. N2K is based on DeviceNet, a very reliable standard for industrial applications. NMEA0183 can short out just as easily.
The NMEA0183 standard is not really a network, its usual topology is a single talker and one or more listeners in a single direction of the data (simplex).

Even using a multiplexer, where all the sentences of several talkers are concentrated, if a talker line is short-circuited it does not affect the rest of the devices.

If we analyze this case, being the same problem in the mast, it does not affect the same in a N2k network as in a "one to one" line using NMEA0183.
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Old 09-09-2021, 09:06   #45
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Re: Wind Instrument

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This depends on the nature of the fault. A short on the power side of the ITC5 would disable the whole NMEA 2000 network (unless you have a divided power supply). The effects of a fault on the data side will depend on the nature of the fault. In most, but not all cases this would only disable the wind instrument. All the above is also true for a pure NMEA 2000 network without the ITC5. I am struggling to see any practical difference other than the ITC5 introduces another complex piece of electronics, and user reports suggest these protocol conversion devices are not particularly reliable.
Agreed, but in the unlikely event the failure mode brings down the entire network, I just unplug it. Easy access.
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