help, powering up chart plotter from seatalk cable is it possible

[rim58]

in the process of fitting a Lowrance chart plotter at the nav station, have an ST60 along side which is powered by a seatalk cable, red,yellow,grey(unsheathed) question is can i power the new chart plotter from here or do i have to go right back to the switch panel.
the Lowrance has red,black,yellow. whats the yellow about??
Anyone know the answer??
thanks,
Bob

 

[superheat6k]

If you have 12v present on the Seatalk wires it might work, but be careful the plotter doesn't draw too much power.

I would expect the yellow is NMEA0183 data out (with black as ground), to other equipment, e.g. DSC VHF set.

What's the model of the Lowrance ?

 

[ianj99]

Depends on the current requirements of the plotter and whether other instruments are also powered via Sealtalk. I think max current via Seatalk is about 2amps however, its not always a 'clean' source of power.

The yellow wire is probably the 'auto switch-on' signal - so the plotter will power up with out needing the power button to be pressed. You connect to -ve for normal operation on my Navman plotter or to the ignition switch for auto power on.
Ian

 

[rim58]

The Lowrance is a HDS-7M
The seatalk powers the main plotter at the binnacle and a ST60 multi at the binnacle with the ST60 repeater at the nav station.
One switch on the panel powers all the nav equipment; VHF radio and main plotter linked together for dsc
thanks,

 

[superheat6k]

Depends on the current requirements of the plotter and whether other instruments are also powered via Sealtalk. I think max current via Seatalk is about 2amps however, its not always a 'clean' source of power.

The yellow wire is probably the 'auto switch-on' signal - so the plotter will power up with out needing the power button to be pressed. You connect to -ve for normal operation on my Navman plotter or to the ignition switch for auto power on.
Ian

Ian is correct for the HDS plotter the yellow in the same cable is the wake up wire.

 

[ianj99]

DO you mean the battery supply is to the main plotter and then the ST60s are powered over Seatalk? If so, then you should be able to power the Lowrance as well.

NMEA in and out are usually blue (in) and white (out). If the yellow is the auto power on, connect it to the black wire (consult the manual).
I

 

[prv]

As Ian says, the standard amount of power available on a Seatalk bus is 2 amps; if you power it from a Raymarine autopilot there is a 2 amp fuse inside the pilot brain that protects the Seatalk.

The spec says that your new plotter draws 0.8 amps. You only have a couple of ST60 instruments, which don't draw much, so the question-mark is your binnacle plotter. What is that?

Also, how is the power supplied to the Seatalk bus? Is it just connected directly via a fuse / breaker? Or, if the binnacle plotter is a Raymarine one, perhaps the plotter is actually powered directly and is providing the output to Seatalk?

It's not clear from your earlier post, but is the VHF also being supplied by Seatalk? I assume not, as a 2 amp fuse would blow as soon as you pressed transmit, but perhaps your Seatalk bus is actually wired so as to have more than the standard 2 amps available?

Coming back to the original question, though - yes, you can power a plotter off Seatalk, as long as there's sufficient power available (that's what we're trying to find out). I have a Lowrance 4m on my binnacle which is powered from Seatalk; this small plotter draws about the same as a couple of ST60s so there's no problem.

Pete

 

[ianj99]

There is a case for not powering the Lowrance via Seatalk in the event the 2a fuse blows when everything would go off (even the main plotter if this is powered this way as well).
I think I personally would run both plotters from independent supplies and just use Seatalk for less critical repeaters/instruments, even if it meant tapping into a nearby lighting circuit (for example) with a suitable inline fuse for the plotter wiring(s).
I

 

[rim58]

just found that behind the panel there is a 3-way seatalk block with 3 x plugs. one plug is power in from the switch on the panel and 2 x plugs out, one to the binnacle plotter Raymarine 9" plotter which is then linked to the st60 multi along side. the second plug powers the ST60 repeater at the nav station.
Thanks for help much appreciated.

 

[prv]

just found that behind the panel there is a 3-way seatalk block with 3 x plugs. one plug is power in from the switch on the panel and 2 x plugs out, one to the binnacle plotter Raymarine 9" plotter which is then linked to the st60 multi along side. the second plug powers the ST60 repeater at the nav station.

OK. Sounds like unlike many boats your electrics panel is not at the nav station?

What size fuse or breaker is there at the panel?

You may very well be able to just hang the new plotter off the Seatalk as-is, but if not it sounds like you also have the option of rewiring slightly behind the panel so that the binnacle leg and the nav station leg have their own separate power feeds (you would connect the yellow data wire across both).

Pete