Garmin GPSMAP's w/ internal antennae

[ElyseM]

i'll be outfitting electronics in the spring. i was wondering how the newer GPSMAPs (Garmin only) with internal receivers operate under a hardtop and within a helm area electronics enclosure (going into a Marlin). are they sensitive enough to get the 9 foot fix range? (my old one with a 19X got down to 7.8 feet.)

Garmin doesn't include an external antennae with the new units. if i have to use an external one i'd prefer to get it done with the installation.

thx much, ron

 

[seasick]

I would expect a hardtop mounted antenna to work better than the built in but how much better? Although the hard top and things like electronics box with stuff in it may weaken reception, there might also be a situation where gear on the hardtop interferes with an external antenna. I am thinking things like radar, other com antennas like AIS etc.
I really don't know.
I am also not sure if the reception strength is the only factor on position accuracy. I would think that the number and spacing of acquired satellites is more critical and maybe that is signal strength related and maybe it more than just that.
Let's have the RF guys chime in.

 

[SkunkBoat]

My EchoMap gets good internal gps reception in the top box. The VHF also gets good gps reception there.

My GPSMAP 4208 gets GPS data from a 19x, as does the autopilot. My 19x is a NMEA 2k version. (There are NMEA0183 versions)
Some don't realize but its not just an antenna, its also the receiver. Powered by the 2k network cable.

Did you remove the 19x? or maybe that was a different boat?

If its a NMEA2k version then leave it on the network. You can choose GPS source in settings, so pick what works best.

 

[ElyseM]

thx. new boat, new setup. going into the helm station. radio will go into the radio box.

 

[Ky Grady]

I'm running a Point-1 external antenna for my Simrad, it's NMEA 2K as well. Takes the question out of the equation on whether the internal GPS has a good signal or not.

 

[ElyseM]

thx. if the internal is close to 100% then no need to spend the extra hundred gallons of gas (my conversion benchmark) and drill holes. if i don't get real life feedback before install, i'll probably just run an N2K backbone up to the radio box and see how the internal functions. that would probably be worth it for future add on's anyway. ron

 

[Hookup1]

Why is position accuracy to that level so important to you? How are you using the boat? If you need position that accurate why not go to a unit that includes the external GPS antenna? No bargains in boating!

Those internal antenna are great for open boats or cruising. For fishing its not the way I go.

 

[ElyseM]

channel markers. sand bars. etc, etc. the radio will have an internal receiver and i will be well ok with a 100 foot error for a DSC emergency, not so much for navigation.

thx, ron

 

[Hookup1]

Sounds like a internal GPS antenna will work for you. Keep in mind the “road most traveled” will have more accurate bottom contours. Most of the bottom charting hasn’t been updated for decades. It’s the channel markers they keep on top of. In my experience go slowly in shallow areas until you develop local knowledge of the area.

if you were telling me you need to precisely and repeatably get on wrecks to fish then you need the most accurate GPS.

If you want to test this some day this try running the ICW from Manasquan to Cape May or AC. High tide covers lots of sins. On a long trip you will have to deal with 5 feet of tide at some point and that is where the charting errors, shifting sand bars and local knowledge come into play.

 

[seasick]

Sounds like a internal GPS antenna will work for you. Keep in mind the “road most traveled” will have more accurate bottom contours. Most of the bottom charting hasn’t been updated for decades. It’s the channel markers they keep on top of. In my experience go slowly in shallow areas until you develop local knowledge of the area.

if you were telling me you need to precisely and repeatably get on wrecks to fish then you need the most accurate GPS.

If you want to test this some day this try running the ICW from Manasquan to Cape May or AC. High tide covers lots of sins. On a long trip you will have to deal with 5 feet of tide at some point and that is where the charting errors, shifting sand bars and local knowledge come into play.

Often when you rely on your sounder to decide if there is enough water to proceed, by the time you find out there isn't, it's too late. The sounder is aft usually. So if you don't know, go slow...

 

[Hookup1]

A good Captain has their head in front the boat not behind it where the sounder is. As SEASICK said: if you don't know, go slow...

 

[ElyseM]

talking about gps fix, not depth. thx, ron

 

[everwhom]

I have 2 7612 units on my 330 Express - one in the upper electronics box and one in the dash. They both get excellent GPS fixes -- haven't checked the actual accuracy, but always spot on. These days I wouldn't bother with getting a hard-top mounted antenna...

 

[Hookup1]

Garmin isn't shipping hardtop GPS heads with any of their units like they did in the past. All units integrate the GPS 19x 10 Hz GPS/GLONASS/Galileo antenna in the units. Updates position 10-times a second. 3-meter accuracy. Much better antenna in that it uses more satellite systems then the GPS 17x and can update position 10-times a second. Both units spec 3-meter accuracy.

I'm beginning a upgrade that will use 8610xsv, 8612xsv, 943xsv and/or 1243xsv units. All have internal GPS 19x antennas. Currently I have a GPS 17x NMEA 2000 and a GPS 17x NEMA 0183 hardtop antennas from my current 4208 and 4210 install. I'll probably pull them both and go to internal GPS antennas.

Also adding a Garmin SteadyCast heading sensor to sync radar to chart plotter since I don't have a autopilot.

 

[ElyseM]

that's the point. the puck is an add-on now. in everwhom's installation, is the signal picked up by the radio box unit or the dash unit (think wifi in your home)? like i said, i'll just run the n2k backbone up to the radio box and see if i need to put in the hardtop puck. thx all, ron

 

[Hookup1]

GPS signal is picked up by an antenna inside the display unit. GPS position sentence is broadcast on both the NMEA 2000 bus and on the display units NMEA 0183 port.

Older radios only support NMEA 0183 connection for DSC position and AIS.

 

[Hookup1]

My upgrade is spiraling up out of control. Saw Garmin GPS 24xd NEMA 2000 antenna. $300 and its in the mail!

Multi band GNSS accuracy to 1 meter. Multiple GPS systems for bigger satellite constelations and 10hz updates. Magnetic heading sensor to correct radar at slow speed for those that don't have a autopilot.

 

[Ky Grady]

Might well go for the Flux Capacitor at this point. I know the feeling.

 

[Hookup1]

In stock? A flying boat would be great! Jaws and Marty McFly are my favorite movies.

 

[Hookup1]

So after doing my latest GPS antenna upgrade and new GPSMAP unit I have a few things to add.

Standalone GPS 24xd antenna GPS/GLONASS/Galileo multi-system, position accuracy, typical marine use: < 50 cm, CEP 50%; < 1.0 meter, 88%

Standalone GPS 19x antenna GPS/GLONASS/Galileo multi-system, WAAS-capable, it can determine your precise location to within 3 m (9.84 ft).

The 8610/8612 units include a built-in 10 Hz GPS/GLONASS/Galileo antenna. Accuracy not specified.

The 943xsc units include a high sensitivity built-in high sensitivity 10hz antenna. Accuracy not specified.

If 3 meter accuracy is all you need the built in antenna should suffice. If you want more accuracy then you need to upgrade units or antenna.