NMEA 2000 cables and connectors

[Sans Bateau]

In the process of installing some (more) NMEA 2000 kit on the boat and I find that I need some additional cables and plugs to go onto the end of long cut cable. The price though is horrendous!

In some places I just want to splice the cable. I cannot see any reason why I should not use a connecting box with screw connectors inside, that is unless someone who knows better tells me so. Otherwise, does anyone know where I can get made up cables or plug/socket ends at sensible money?

As an aside, whilst I have the attention of those much better informed than me on NMEA 2000, can you tell me please, if I were to plug a NMEA 2000 plotter into the backbone, of a different make to the main plotter, what am I likely to see/read/experience?

 

[David2452]

As an authorised NMEA 0400 and 2000 techie and member of the NMEA I can confirm that the use of barrier strips (not chocolate blocks) is and acceptable practise for installations to conform to NMEA2000, provided they are done propely with ring theminals and the junction is not in an exposed area. So go ahead. Also if you know a friendly factory process engineer the stuff is all lifted from devicenet including cables and connectors so you may get some from such a source cheaper.

Edit as I didn’t see the second question, two plotters both complying to N2K could give a few issues but simply shut the transmit down on one so all the other kit on the backbone only has one set of data to work with, many instruments will allow you to select the "source" of information they use and you could also go down that route if the facility is available. Take particular care if the "new" plotter has an N2K antenna as that will feed directly to the network and will be difficult to ignore. If one plotter goes down then you can always reinstate the transmit from the other one on the backbone. If you post precicely what kit you have connected I may be able to give a more meaningful answer.

 

[Sans Bateau]

As an authorised NMEA 0400 and 2000 techie and member of the NMEA I can confirm that the use of barrier strips (not chocolate blocks) is and acceptable practise for installations to conform to NMEA2000, provided they are done propely with ring theminals and the junction is not in an exposed area. So go ahead. Also if you know a friendly factory process engineer the stuff is all lifted from devicenet including cables and connectors so you may get some from such a source cheaper.

Edit as I didn’t see the second question, two plotters both complying to N2K could give a few issues but simply shut the transmit down on one so all the other kit on the backbone only has one set of data to work with, many instruments will allow you to select the "source" of information they use and you could also go down that route if the facility is available. Take particular care if the "new" plotter has an N2K antenna as that will feed directly to the network and will be difficult to ignore. If one plotter goes down then you can always reinstate the transmit from the other one on the backbone. If you post precicely what kit you have connected I may be able to give a more meaningful answer.

Thank you Dave, the first part of your answer tells me what I shouldnt use, but what the hell is a "barrier strip" and a "ring terminal"?

The system I am installing is Garmin. I have a 4008 plotter and I am in the process of installing GM1 wind/depth/speed. I understand that I can display the information from the displays on the 4008. I am installing 2 x GM1's at the helm, to give me wind and depth/speed simultaneously. I would like to access information at the nav table and wondered if a cheaper plotter that supports NMEA 2000 would do the job. The GM1's are the price of a cheap 5" plotter!

 

[David2452]

Here’s a barrier strip http://www.tcdirect.co.uk/deptprod.asp?deptid=280/7 obviously you need the 5 pair type, they are available from here or your local Maplins & others. The ring terminals are the same as any normal electrical ones but of a micro size to suit the barrier strip screws, available from the same place as the strips, possibly the supplier may call them lugs.
The Garmin kit will all plug and play so no problems there, the 17x GPS puck supplied with the 4008 will feed all GPS data direct to the bus so the Garmin stuff will all use that data, as will any other stuff like wind, depth, water speed sensors. What you can do at the chart table will depend on a number of things and a cheap N2K plotter plotter sans Antenna may be the way to go as it will take it’s feed from the bus, but you will have to check the particular unit’s spec to see what it is capable of displaying. One point worth mentioning is that most Garmin stuff comes with quite a bit of N2K cabling, terminators and “Ts” so you may not need to go down the barrier strip route at all. The 4008 comes with quite a long so called drop cable for the 17x that is actually over the length specified to be N2K compliant for a drop but works OK, a better way is to place the 17x right at one end of the backbone using an inline terminator (very cheap) which is both compliant, works and frees up a “T” from the 4008 Kit for use on another drop and use another inline terminator for a device at the other end of the backbone thus requiring two less Ts than would otherwise be the case, you will still be left with future flexibility using that method. I have a similar setup on my own boat but have two off 17X one of which has a switch in the power supply so I can switch over to that one if the other goes down. Make sure you always update the 4008 to the latest (bulk) firmware as it will update the rest of the N2K stuff at the same time when its all up and running along with any radar, GSD22 sounder module etc on the proprietary Garmin network.

 

[Sans Bateau]

David

Thank for your help so far, sorry but I do have more questions, hope you dont mind.

Why is a barrier strip so important? I was planning on using the old Raymarine connecting boxes which I believe are simple 'choc box' type. This is an academic question, as if I need to join anything the barrier strips look cheap enough.

I cant promise that there will not be other questions, if you dont mind.

 

[David2452]

It's simply that I wouldn't use any connector that relies soley on direct screw pressure to retain the conductor and maintain good electrical contact and not simply because the NMEA specs specificaly exclude this method. The chocolate blocks where the screw presses down a flap onto the conductor are much better but when the superior stuff is available at such low cost why bother. In fact if you just twisted the conductors together and insulated them from one another it would work, but for how long and how well? and what if somebody saw it.

 

[Sans Bateau]

Understood, I agree the barrier strips are so cheap it has to be the answer.

Once again thank you for your help.

 

[richardsnowstar]

The system I am installing is Garmin. I have a 4008 plotter and I am in the process of installing GM1 wind/depth/speed. I understand that I can display the information from the displays on the 4008. I am installing 2 x GM1's at the helm, to give me wind and depth/speed simultaneously. I would like to access information at the nav table.....

I have a similar setup with GM10's in the cockpit and a 4008 at the nav station. The 4008 will display the wind/depth/speed info around the edges of the chart display. I am not sure why you want additional displays if you can get the info on the 4008. Is the 4008 not at the chart table?

 

[Sans Bateau]

I have a similar setup with GM10's in the cockpit and a 4008 at the nav station. The 4008 will display the wind/depth/speed info around the edges of the chart display. I am not sure why you want additional displays if you can get the info on the 4008. Is the 4008 not at the chart table?

Richard, the 4008 is at the helm (the correct place) I will have 2 GM10's at the helm replacing the old ST50's, but I also had ST50's at the chart table, I would like in the future to have the chance to view information there as well.