AIS Technical Question - GPS input

[Slowboat35]

I am looking at fitting an AIS transponder, possibly the Emtrak 954 as I need a splitter, WiFi, USB and NMEA2000
The blurb says a GPS antenna is "optional". I staht because the internal antenna might not pull in a strong enough signal, or is it just fir a stand-alone installaton?

Does it really need its own antenna if networked with a NMEA2000 chartplotter? Can it read the chartplotter's own GPS or am I missing something?

 

[Buck Turgidson]

It's not allowed to read another GPS positions, it must be independent. Other systems are allowed to read it's GPS position. The model you quote has an internal GPS receiver so the optional external antenna would be for an installation where no signal was present. That will depend on where you put it and what your hull and deck are made of.

 

[Slowboat35]

Oh bother...
What chance do I have of it seeing a GPS signal inside a pretty solid GRP hull?

 

[awol]

Oh bother...
What chance do I have of it seeing a GPS signal inside a pretty solid GRP hull?

That's where my AIS GPS aerial is, below the deck.

 

[PaulRainbow]

Oh bother...
What chance do I have of it seeing a GPS signal inside a pretty solid GRP hull?

Every chance, fit it as close to the deckhead as possible. I've fitted several of the Emtrak AIS units and all but one have worked flawlessly below decks (the one that doesn't is currently under investigation).

 

[[70521]]

My AIS and VHF use their internal antenna below decks.

My phone can give me a GPS location within buildings.

 

[jwilson]

Almost all modern GPSs work perfectly inside GRP hulls: I've just fitted an Emtrak B953 and the GPS works fine below decks. In fact any modern GPS gets a better fix faster from below deck than the one old external Raystar "mushroom" aerial on the stern rail ever did. The Raystar 125 is still working, but it often takes 20-40 seconds to show a fix: in the meantime the GPS inside a newish VHF radio at the chart table gets a fix in 5 seconds.

 

[srm]

Oh bother...
What chance do I have of it seeing a GPS signal inside a pretty solid GRP hull?

The most likely problem is from metal that is in the way. I lost internal GPS reception after adding foil backed thermal insulation to the sandwich deckhead of my previous boat.

 

[tjbrace]

Oh bother...
What chance do I have of it seeing a GPS signal inside a pretty solid GRP hull?

Both of mine are below deck and they seem to work ok.?

 

[mikegunn]

Both of mine are below deck and they seem to work ok.?

Ditto!

Mike

 

[Bilgediver]

That's where my AIS GPS aerial is, below the deck.

MIne also works well in a side locker.