Where is your GPS sensor located?

Bloater

Bloater

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I am in the process of fitting all-new electronics to my sailing boat.

I am fitting a Garmin system and the GPS sensor will be connected to a NMEA2000 network, however the maximum 'drop' cable length is (supposed to be) limited in length to less than the distance to the pushpit rail that the existing sensor is located. Moving the network 'backbone' nearer by buying extra cables/connectors etc is an option that I wanted to avoid as they are relatively expensive.

I therefore wanted to flush-mount the new GPS sensor on the coachroof - just in front of the sprayhood, in between two dorade vents where it won't be trodden on.

My question is: Is there a problem with this location (being under the boom)? If not, why are most of the sensors that I see mounted on pushpits (where they are likely to foul lines)?

Many thanks, Ian.
 
I don't have a fitted GPS at the moment, I use a portable Garmin plugged into the system.

What I would be interested in is why is the sitting of the receiver so pedantic on a boat? I use mine just about everywhere and never have an issue with a signal. On aircraft, on mountains, in trains, cars and buses, it even works indoors.
 
I have a complete Garmin setup, with NMEA2000 devices and 3 separate Garmin GPS aerials.

ALL of my aerials are fitted INSIDE the boat. There really is no need to put them outside.

I have one under the side-deck and two in the lazarette.

All have very good signals.

Keep your cable short and keep them inside.

My whole installation was supervised by Garmin (they used my boat fro their brochures) and they recommended we do it that way. Easier to wire, no holes for leaks, no glands, no UV degradation, no risk of breakage.

I really recommend you plug your sensor in and try it inside the boat, and then move it outside and you will see there is really no difference. When we built our boat we had am almost perfect signal inside the boat when it was still in the factory! Garmin sensors are very good!
 
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I have the Garmin (1700?) fitted to the underside of the wheelhouse roof, works a treat and it don't get stood on...
You should have got an "underneath" fitting kit with the aerial, I would strongly recommend it, as it can "hear" through plastic OK. The spars are a don't care function as they won't stay in line with a satellite for long enough to cause problems.
It will stay dry, and it's one less hole for the rain to come through.
 
Despite all the warnings about "unimpeded view of the sky" that seem to come with most GPS units, the signal seems surprisingly resiliant. Even putting a metal saucepan over the aerial hardly seems to faze it (I've tried).

The best advice must be to use a signal tester. Luckily most units have one built-in :D. As Solentboy suggests, if practicable wander around the boat to test the effect of various locations.
 
I've used GPS antenna mounted inside of balsa sandwich deck with no problems. However, I've seen a consistent signal loss when someone sits on the deck right above the antenna... Should've taken a position where sitting or sunbathing is not practical
 
I didn't want to cut the coach roof or fix to the pushpit.

I thought I would try my luck as high as possible under the coachroof between the inner and outer bulkhead to starboard of the companionway. Its been there for two seasons without any problems.
 
I've got three gps antennae, one proper one mounted on push pit.

The other two are e-bay cheapies, one stuffed inside the binnacle instrument pod, t'other taped to top of radar display at chart table.

There is no discernible difference in performance between the three units.

So maybe location isn't as critical as some may suggest.
 
Have two sensors down below - one a dongle from Maplin, the other a Garmin with built in ariel. No problems with signals.
 
Judging by all of your replies it seems that I should at least try to find somewhere inside the boat to fit it. It's a Garmin GPS17x and it did come with an under-deck mount.

It makes a lot more sense than either drilling a hole, or mounting on the pushpit rail (where the mooring lines can get fouled on it when mooring up in a panic).

Many thanks for all your speedy replies. Ian.
 
I think older antennas may have been more sensitive to obstruction than modern ones. Certainly sailing with my parents years ago, putting one's hand over the pushpit antenna would reliably cause the GPS to lose its position and start beeping. To this day in our family, the GPS antenna on a boat is known as "the GPS gnome" because of my dad's characterisation of a creature inside it peering at the satellites with binoculars and shouting "Gerroff! Get yer bleedin' hand out me way, I can't see!"

Agree that there's no need to be so careful with modern ones.

Pete
 
I have a Garmin 551 plotter with internal antenna, mounted in the roof of Gladys' wooden wheelhouse, and always have "five bar" reception, and that's right under the boom when hard on the wind
 
I have a tatty old Snapdragon with, to look at her, nothing worth nicking on board. The last thing I wanted to do when I got the GPS was to advertise its presence to every scrote who's out in a dinghy collecting kit for his next boat jumble, so I put it inside the lazarette, where it's worked fine for many years.
 
I wish I had read this thread before mounting my garmin GPS antenna. I put it on the pushpit and have a leaking gland to sort. Get a very good signal but inside would have been better.
 
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