GPS Antenna ?

[Legend]

HI. Purchased a new multi-function Garmin GPS unit and it says it has an internal antenna. Has the option for an external antenna. Anyone with a fairly new GPS using just the internal antenna and is so any issues with satellite reception? The unit is to be installed in a Sailfish, under the hardtop and surface mounted in the cockpit. Thanks for any feedback.

 

[Coastboater]

I’ve installed a few, all with internal antenna and never had a problem picking up satellites. A couple were hardtops.
You should be fine and if not add the external antenna later.

 

[Halfhitch]

Same as Coastboater here. Just connect your Garmin to a NMEA 2000 system and all your other instruments will be able to make use of it. Like your VHS, autopilot, or any NMEA 2000 capable gizmo.

 

[Ekea]

mine is mounted just above my steering wheel (so lower than yours), i have no external antenna and it does fine

 

[SkunkBoat]

The internal GPS should be fine. It will share with the network.

To clarify though, external GPS "antenna" is a misnomer. Nowadays, the NMEA2k units are actually a complete gps receiver and antenna, powered by the n2k.

Garmins latest version is GPS24xd that also has a built in heading sensor. Your chartplotter does not have a heading sensor.
A heading sensor gives an accurate display of where the bow of the boat is pointed, even when you are not moving. Without a heading sensor, the gps heading is calculated based on movement (it assumes you are moving forward). Under 3mph you may not get a good gps heading. When you are drifting, the display will show the bow pointed in the direction you are drifting, not the direction the bow is actually pointed.

Radar and Autopilot will require a heading sensor.



The Garmin mfd can be set to use the built-in or choose from network gps units if you have more than one.

IDK what you had before. If you had any brand of n2k gps unit, it will work if its on the network.

 

[Sardinia306Canyon]

I had many GPS on my boats and all are installed on the dash on the console and GPS reception worked fine.
However, depending on position, materials, cable mess, hard top structure reception of GPS signals can be reduced.
I have now a 800$ Garmin MSC-10 Satellite Antenna acting as Heading Sensor and Multi-band GPS Receiver and it's a different world. Buch better AP accuracy, very good GPS SIgnal strength and Heave Compensation for my GT51M-TM.
Normal NMEA2000 GPS antennas cost around 2-300$ what i find a acceptable cost for more accurate position data, if internal GPS antenna has limited reception.
Chris

 

[wahoo33417]

My Garmin works really well flush-mounted at the dash under the Sailfish hardtop. Also seems to give great position data to the autopilot.

Like Coastboater said, try it. You can always add the GPS/heading sensor later.

 

[gw216]

HI. Purchased a new multi-function Garmin GPS unit and it says it has an internal antenna. Has the option for an external antenna. Anyone with a fairly new GPS using just the internal antenna and is so any issues with satellite reception? The unit is to be installed in a Sailfish, under the hardtop and surface mounted in the cockpit. Thanks for any feedback.

I had mine setup using the internal GPS antenna, but it wasn’t accurate enough for my Seakeeper Ride system to work properly after Seakeeper’s latest update. I installed a Garmin GPS24xd external antenna with heading sensors and it is a huge improvement. It went from an EPE(M) of 3.5-4.25 to 0.85. It was well worth the $245 to upgrade. I highly recommend adding it to your system.

 

[Ekea]

I had mine setup using the internal GPS antenna, but it wasn’t accurate enough for my Seakeeper Ride system to work properly after Seakeeper’s latest update. I installed a Garmin GPS24xd external antenna with heading sensors and it is a huge improvement. It went from an EPE(M) of 3.5-4.25 to 0.85. It was well worth the $245 to upgrade. I highly recommend adding it to your system

at the risk of derailing this thread, why does the SKR need highly accurate gps input? i assumed the only gps input to SKR was speed, but also assumed that high accuracy isnt as cruicial for speed as it would be for pitch/roll/yaw and acceleration g's

 

[gw216]

at the risk of derailing this thread, why does the SKR need highly accurate gps input? i assumed the only gps input to SKR was speed, but also assumed that high accuracy isnt as cruicial for speed as it would be for pitch/roll/yaw and acceleration g's

From what I understand, speed, GPS accuracy, and the ability to account for changes in speed and direction are inputs the system relies on to make the numerous adjustments it makes per second. An EPE(M) of 3.0 and above can cause the SKR system to switch from Auto to Manual mode. Prior to the last update, the SKR system did not require the GPS to be as accurate. In addition to improving the SKR, the external antenna acquires satellites much faster, and every other device on the NMEA network benefits from the improved signal. Now that I see the difference, I wish I had done it earlier.

 

[bcoco]

not to derail, but how do you like the SKR. is that on the 216 ?

 

[Sardinia306Canyon]

not to derail, but how do you like the SKR. is that on the 216 ?

Wha not sending him a PM here or open a new tread to NOT derail this one?
Chris

 

[bcoco]

didn't think of that sorry

 

[gw216]

not to derail, but how do you like the SKR. is that on the 216 ?

Yes, it is on the 216. I love it; it's a game changer. It makes the boat feel and ride like a much bigger boat, and it gets on plane much faster. It should be a factory option, as Regulator Marine and other boat builders are offering. The SKR system and the trolling motor have made my little boat much more enjoyable.

 

[seasick]

From what I understand, speed, GPS accuracy, and the ability to account for changes in speed and direction are inputs the system relies on to make the numerous adjustments it makes per second. An EPE(M) of 3.0 and above can cause the SKR system to switch from Auto to Manual mode. Prior to the last update, the SKR system did not require the GPS to be as accurate. In addition to improving the SKR, the external antenna acquires satellites much faster, and every other device on the NMEA network benefits from the improved signal. Now that I see the difference, I wish I had done it earlier.

As I understand it ( and I have the SKR450 system), the system's strength is in controlling pitch angle and list angle. That is not something derived from GPS That data comes from a gyro like module. I have autopilot and I think that it's gyro compass is used by the Ride controller for pitch/roll and mayne speed.

My boat has a lot of electronically controlled devices most of which talk over the N2K network. It is not easy to see what it talking to what.

 

[gw216]

As I understand it ( and I have the SKR450 system), the system's strength is in controlling pitch angle and list angle. That is not something derived from GPS That data comes from a gyro like module. I have autopilot and I think that it's gyro compass is used by the Ride controller for pitch/roll and mayne speed.

My boat has a lot of electronically controlled devices most of which talk over the N2K network. It is not easy to see what it talking to what.

Seakeeper's tech support told me that the new update requires a strong, reliable GPS signal that maintains an EPE(M) of less than 3.0, so the software uses GPS data to control and adjust the vessel's attitude. Prior to the 2026..4.1 software update, my system worked fine using the internal GPS. The latest update required more accurate GPS data, so I had to install an external antenna. Exactly what the SKR algorithm uses the GPS data for, I really do not know.

 

[seasick]

I read some of the Seakeeper info and it states that the software module has internal motion sensors that it uses to measure pitch, yaw, and roll.
I also now understand the role that the GPS data plays.
Basically the GPS provides speed information which is used both to enable automatic operation at speeds over 10 mph and adjust response times and magnitude at speed.
One other thing to note is that under 10 mph, and if you have the optional keypad, the tabs can be manually controlled similar to traditional trim tabs. I have used the keypad at speed to override the Ride settings in certain seas to reduce excessive spray over the bow in rougher seas. Honestly I am not sure if that manual trimming turns off any automatic action but I assume it does. I have played a bit with the configuration of the profile to raise the bow a bit at speed but I don't have enough data to know how that affects the trimming during calm seas. Things used to be simpler

 

[gw216]

I read some of the Seakeeper info and it states that the software module has internal motion sensors that it uses to measure pitch, yaw, and roll.
I also now understand the role that the GPS data plays.
Basically the GPS provides speed information which is used both to enable automatic operation at speeds over 10 mph and adjust response times and magnitude at speed.
One other thing to note is that under 10 mph, and if you have the optional keypad, the tabs can be manually controlled similar to traditional trim tabs. I have used the keypad at speed to override the Ride settings in certain seas to reduce excessive spray over the bow in rougher seas. Honestly I am not sure if that manual trimming turns off any automatic action but I assume it does. I have played a bit with the configuration of the profile to raise the bow a bit at speed but I don't have enough data to know how that affects the trimming during calm seas. Things used to be simpler

That makes sense. Yes, I have the keypad. You can use it to adjust the tabs at any speed in manual mode; similar to regular trim tabs. That is what I used to get home when the Auto setting kept shutting off without warning. You can use the SK app on the MFD or the keypad to adjust in Manual and Auto Mode. I mainly bought the SK keypad to replace the Bennett one, since it no longer served a purpose. I do not believe any settings made via the keypad in Manual mode affect the Auto feature, but I believe the adjustments made in Auto will remain until you change them back. It is nice to be able to use them in manual mode, but the boat did not respond as well as it did with the OEM trim tabs. Seakeeper Ride is an amazing system that makes things easier, but you definitely still need to understand how to trim manually.