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Surface mount GPS Antenna


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I am after a surface/deck mount GPS antenna for a SOTDMA AIS.  Does anyone know where these are sold in NZ?

The AIS came with a stub antenna, pictured below, but this will get ripped off the first time a rope goes around it.

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Pretty sure the lower housing is removable, you''l then be left with a deck mount puck. Looks to be the same style as B&G antenna which we deck mounted.

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2 hours ago, Bradz said:

Pretty sure the lower housing is removable, you''l then be left with a deck mount puck. Looks to be the same style as B&G antenna which we deck mounted.

Thanks.  Only the very bottom bit unscrews.  The downward facing cone part is part of the base.

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52 minutes ago, Guest said:

If the top is not stand-alone, garmin have a passive. (TNC) for $90 . 

http://mrmarine.co.nz/catalog/product/463

Thanks.  This statement on that link is interesting ...

.. and provides three easy mounting solutions: pole mount, surface mount or under-deck mount (for the underside of fiberglass decks).

I have sometimes heard that GPS/GLONASS signals work fine through fibreglass/ply - my other antenna is built into the chart plotter and is mounted on a swing frame into the companion way - we never lose signal when it's inside even when the companion way is closed... makes me wonder if I should just mount it under the deck ...

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i got something similar with my vesper unit, i mounted it behind the instrument panel, otherwise it would have disappeared with the first rope to catch on it,  I know that maritime radio can see me from 20 mile so must be getting a reasonable signal out though the deck

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1 hour ago, waikiore said:

The Raymarine GPS is a small low profile puck

Thanks - I believe that these are full NMEA2000 units, not dumb antennas, so these would not be compatible.

The AIS standard requires AIS transponders have a dedicated built in GPS receiver, so they can't use another source off the network.

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I bought one off Ali Express for my SOTDMA AIS, which was about $40 delivered. I got a rail mount from Burnsco and have it on the pushpit. Worked far better than the built in GPS on the new chart plotter mounted in the cockpit bulkhead which lost signal fairly often.

The AIS came with one of those small pucs which I had below but would show us doing up to 1kn when moored in the marina!

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One knot on a stationary boat's GPS is pretty common, and not due to unit quality or any fault. It's due to the error present in the GPS signal. This is one of the multiple reasons that GPS only is a dangerous way to navigate.

If a bulkhead mounted MFD (Plotters are obsolete! - its a Multi Function Display), where the GPS is positioned in the bulkhead can be problematic in some installs - if the bulkhead is thick, and covers the GPS antenna location, you are asking the antenna to "see" through the whole depth of material up to the deck/cabin top - could be 300mm or more. That wont work well. 50mm of GRP or timber is no issue, so through a deck - no problem, unless it's metal.

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On 11/03/2022 at 4:19 PM, Young Entertainer said:

i got something similar with my vesper unit, i mounted it behind the instrument panel, otherwise it would have disappeared with the first rope to catch on it,  I know that maritime radio can see me from 20 mile so must be getting a reasonable signal out though the deck

The AIS transmission is from whichever VHF aerial you plug your AIS into - on yachts it's usually masthead via the splitter.  Hence the distance.  The GPS aerial under your deck just provides your position to the AIS unit.  Ours is the same, GPS under the deck on the GRP Ross 40.  But we had to mount it outside on the all carbon boat.

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