Help! I may need to jury rig a GPS antenna

[Deleted User YDKXO]

The Lorenz GPS antenna on my boat failed last time out and I needed to replace it. I left the problem with a local maintenance co in Croatia but they've just sent me an e-mail telling me they can't get a replacement GPS antenna of any sort let alone a Lorenz (despite me giving them the prob to sort 2 weeks ago). I did try to get a Lorenz antenna in the UK but they're not sold here. A well known UK marine electronics co, who I wont embarass by naming, told me that a Standard Horizon antenna would be a straight swap but it's pitched up today and its completely different and its without a mounting so I can't even fit it to the boat.
Trouble is that I'm flying to the boat tomorrow with some mates for our annual boys trip and I wanted to take them to some places I've not visited before. Yes I could use trad nav to get us around but the local charts are small scale so a plotter is v useful.
So, I've got a cable coming out of the radar arch, a duff GPS antenna attached to it and a new antenna which doesn't fit and hasn't got any mounting at all so I can't even tape it or cable tie it in position. The other prob is that the cable plugs are different between the old antenna and the new so, even if I can find a way of fixing the new antenna in position, I need to cut the cables and join them with a block. Both cables seem to be 5 core (DIN?). Will it be OK to join the same colour wires together, if they are the same, or is that just too easy? If the wire colours are different, what then?
Anyone got any good ideas?

 

[bendyone]

Will your plotter take another GPS Nema input? If so use a H/H GPS with a Nema output and connect the two together

 

[hlb]

When I had a simmilar problem, I was told any one would do.

 

[duncan]

whilst calling Lorenz in Milan and getting them to confirm the cable designation to rig in another aerial is one option, you may have some workarounds.

if you have any other GPS devices on board they may have NMEA 0183 interfaces and the Lorenz unit may have another COM port to recieve this (other than the direct wiring of a GPS aerial.

you could get one (hand held at the airport or something else at the other end) focusing on the need for NMEA out port and cable (wires) - will just be a data+ and data- (or ground).

given you have the SH one, and it will have a manual (I can't source a Lorenz CP manual or the 12 channel GPS aerial they use I am afraid) the call to Lorenz and a 5 way connector block would be starting point - large cable ties or duck tape to mount it somewhere (anywhere really) for the trip.

 

[jfm]

I think you mean GPS engine, not antenna (becuase 5 wires not coax)? In which case it'll be nmea 0183 output, so just buy a nmea0183 output engine from another maker eg raymarine or furuno (not garmin, that will be nmea2000) and connect it up. You can find the two nmea wires into your plotter from its manual or online spec, so connect the two wires from the new gps engine to those two colours and job done

 

[duncan]

I think you mean GPS engine, not antenna (becuase 5 wires not coax)? In which case it'll be nmea 0183 output, so just buy a nmea0183 output engine from another maker eg raymarine or furuno (not garmin, that will be nmea2000) and connect it up. You can find the two nmea wires into your plotter from its manual or online spec, so connect the two wires from the new gps engine to those two colours and job done

can you point to an online manual? can't find one anywhere and Lorenz don't seem to provide facility...but I see your point - the SH unit is already delivering an NMEA message and the L unit is taking a data feed rather than an aerial signal already so getting another GPS is pointless.

 

[DAKA]

The Lorenz GPS antenna on my boat failed last time out and I needed to replace it. I left the problem with a local maintenance co in Croatia but they've just sent me an e-mail telling me they can't get a replacement GPS antenna of any sort let alone a Lorenz (despite me giving them the prob to sort 2 weeks ago). I did try to get a Lorenz antenna in the UK but they're not sold here. A well known UK marine electronics co, who I wont embarass by naming, told me that a Standard Horizon antenna would be a straight swap but it's pitched up today and its completely different and its without a mounting so I can't even fit it to the boat.
Trouble is that I'm flying to the boat tomorrow with some mates for our annual boys trip and I wanted to take them to some places I've not visited before. Yes I could use trad nav to get us around but the local charts are small scale so a plotter is v useful.
So, I've got a cable coming out of the radar arch, a duff GPS antenna attached to it and a new antenna which doesn't fit and hasn't got any mounting at all so I can't even tape it or cable tie it in position. The other prob is that the cable plugs are different between the old antenna and the new so, even if I can find a way of fixing the new antenna in position, I need to cut the cables and join them with a block. Both cables seem to be 5 core (DIN?). Will it be OK to join the same colour wires together, if they are the same, or is that just too easy? If the wire colours are different, what then?
Anyone got any good ideas?

I agree with jfm, the antenna only needs a coax and most are interchangeable.

I would return the engine you have been sold and spend a little more buying a complete seperate system such as this

http://cgi.ebay.co.uk/Navman-5505i-...tEquipment_Accessories_SM&hash=item35ac494091

That ius a really cheap one, expect to pay £300-£600 .
It has an integral anntenna, plugs into a 12 volt cigar plug and thats it, you can move it upstairs/down as you require.

This weekend all you need do is plug it in and use bluetack on the mount.
with the best will in the world you are not going to find time with your mates there to join complex wires together.

The next time you go you can take a nmea 0183 output from the power lead supplied and join that to your main fixed plotter.


benifits

you can play with it at home or in the boat with any 12v supply until youi know your way arround it

it is a seperate spare system


I have 3 seperate systems on my boat.
Even The upper dsc is supplied by a seperate neam0183 source to the lowerhelm.

 

[MapisM]

Yes I could use trad nav to get us around but the local charts are small scale so a plotter is v useful.

Well, you can still use the plotter charts, even without the GPS data.
Either yourself or at least one of your mates will surely have a mobile with a gps, to check your position on the plotter, whenever needed.
This is a simple but also very rough solution of course - still better than trad nav with no proper charts, anyway...
Otoh, making the plotter fully operational by tomorrow, assuming that all you've got is the new SH mushroom to connect to the plotter, as DAKA says is not trivial.
You should understand which is the pair of wires for NMEA out from the mushroom, attach them to the NMEA in to the plotter, and configure the plotter according to the engine output.
But that's not all, because the mushroom has to be powered, so you should also understand and properly connect also the power wires. Not to mention that I wouldn't be 100% sure that both Lorenz and SH mushrooms use the same voltage. And if not, you'd better return the SH mushroom to that well known shop and explain them politely what to do with it...

 

[Deleted User YDKXO]

Thanks guys for all replies. After I went ballistic yesterday with the Croatians, they have informed me today that they have found a Northstar GPS antenna (engine?) which they say they are going to have fitted by tomorrow. I must admit that, after your replies, I was even more daunted about wiring up the SH unit myself so this is a relief
To DAKA, I know the Navman 5500 very well as I had it as a stand alone back up unit on my last boat. In 5 yrs I didnt have cause to use it anger and stupidly I sold it with the boat. Yup, I could have done with it now
To Mapism, actually this was the way we navigated for the last few days of our last trip on the boat because we weren't getting a GPS signal. We used a combination of paper charts and moving the plotter screen to where we thought we were. Not ideal in Croatian waters where the pilotage can be intricate, as you know

 

[MapisM]

Not ideal in Croatian waters where the pilotage can be intricate, as you know

Yup, 100% agreed. IIRC, for the western coast of Istria alone I had an 18 waypoints route stored in my plotter...
I did call it a "very rough solution", in fact.
Happy to hear that you eventually managed to get a commitment from the Croatians, I only wish you it'll materialise!

Re.antenna vs.engine, actually nowadays the first is practically disappeared, but the latter is still commonly called "antenna", as was the first. But if you're interested in the difference, before GPS chips were miniaturised enough, the mushroom used to be just an antenna, receiving the sat signals and sending them through a coaxial cable to the plotter, which eventually did all the math required for a fixing.
Nowadays, the GPS chip is directly inside the mushroom, and what is sent to the plotter is the final result - i.e. the so called NMEA sentences. The plotter just has to use them and show the position, SOG, etc. on the display.
That's why these mushrooms are called "engines", and require multi-wire cables, but as I said even the installers (most of them, anyway) continue to call them antennas...

 

[Bilgediver]

I agree with jfm, the antenna only needs a coax and most are interchangeable.

This does not apply to all....The SH plotter does not include a GPS!!! Like some others the GPS is in the mushroom on the taffrail.

The GPS takes aa voltage from the SH plotter and sends a NMEA signal back using 5 small wires as the OP has already confirmed and does not use coax.

It is easy enough to find out the colour coding of the SH plug as I believe it is in the manual however the lorenze might be a problem. A choc block would be fine .

The SH GPS antenna fits on a standard plastic mount available in most chandlers. Either the swivel type or rail mounted.

I shall check later today for the SH colours.

 

[Bilgediver]

I shall check later today for the SH colours.

SH colours are..

pin 1 red 12v +
pin 2 green GPS ant data out NMEA
pin 3 brown GPS ant data in NMEA
pin 4 not used
pin 5 not used
pin 6 black/yellow battery negative

 

[Deleted User YDKXO]

SH colours are..

pin 1 red 12v +
pin 2 green GPS ant data out NMEA
pin 3 brown GPS ant data in NMEA
pin 4 not used
pin 5 not used
pin 6 black/yellow battery negative

Many thanks

 

[Deleted User YDKXO]

Yup, 100% agreed. IIRC, for the western coast of Istria alone I had an 18 waypoints route stored in my plotter...
I did call it a "very rough solution", in fact.
Happy to hear that you eventually managed to get a commitment from the Croatians, I only wish you it'll materialise!

Re.antenna vs.engine, actually nowadays the first is practically disappeared, but the latter is still commonly called "antenna", as was the first. But if you're interested in the difference, before GPS chips were miniaturised enough, the mushroom used to be just an antenna, receiving the sat signals and sending them through a coaxial cable to the plotter, which eventually did all the math required for a fixing.
Nowadays, the GPS chip is directly inside the mushroom, and what is sent to the plotter is the final result - i.e. the so called NMEA sentences. The plotter just has to use them and show the position, SOG, etc. on the display.
That's why these mushrooms are called "engines", and require multi-wire cables, but as I said even the installers (most of them, anyway) continue to call them antennas...

Thanks, I didn't appreciate the difference

Well, you were right. The commitment from the Croatians didn't materialise. They didn't get the GPS engine in time. Luckily, I took the SH engine with me and I got a local electrician, who turned out to be very good, to connect the wires. But I still didn't have a working plotter as Navionics UK sold me a duff cartridge without any files on it. I made the mistake of sending them my old chart cartridge for updating. Still the weather is very nice in Croatia and it makes a change to navigate using paper charts

 

[jfm]

Originally Posted by DAKA
I agree with jfm, the antenna only needs a coax and most are interchangeable

This does not apply to all....The SH plotter does not include a GPS!!! Like some others the GPS is in the mushroom on the taffrail.

Just to be clear, Daka was not agreeing with me. He said coax, which is wrong, whereas I said days ago what you've now said which is that Mike's "antenna" is actually a gPS engine with nmea0183 output