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I'm looking for feedback regarding factory installed AIS on a Beneteau. My OC45 came with the NAIS-300 unit that was installed sharing the VHF Radio Antenna. I know this is not the best but the dealer claims otherwise. My range is lousy.
AIS-B Targets <1.5kn
AIS-A Targets <8kn
I want to install a second antenna but obviously feel this should be the responsibility of the manufacturer. The installation as is does not perform anywhere near what should be expected.
There is nothing wrong with AIS sharing the VHF antenna as long as you have a quality splitter. Frankly, you will get less range installing a second antenna as it will need to be lower than your VHF antenna (usually mounted on the spreader).
I get AIS-A targets at 25nm and AIS-B targets at 8NM. I have a shared antenna with a Vesper splitter.
Ok. Good feedback, thanks. The boat is 3 years old and I've only had it for two of those. Given that I have only started scrutinizing the AIS just recently I suspect it was bad from the start. I will look at the connections to the splitter and AIS unit. The radio seems fine and has good range.
Based on other findings throughout the boat it would not surprise me if there was a workmanship issue with a cable and connector or the like.
At the ranges you are giving how many targets are there? It is most likely a range issue but in very heavily trafficked areas the number of ships can also reduce the visible range.
The NAIS-300 is limited to 250 targets, so this could be an issue near a large port.
Number of targets is not an issue in my case but thanks for the suggestion. Refresh also seems a little slow. I've read that NMEA 0183 should be transmitting in high speed mode but I have yet to figure out if that is programmable or even an issue.
NEMA 0183 is a very slow connection its only 4800 baud. I am not enough of an expert to tell you, but it wouldn't surprise me if the slow connection could also be limiting the number of targets visible.
Again my bet is the above is right and you just have a bad connection, but it wouldn't be impossible for a slow connection to cause it as well.
If possible I'd go with the two antennas - I have one on my spreader and one on the masthead.
Apart from anything else, it's nice to have the redundancy - I mounted my AIS transponder and VHF right next to each other so I could switch the cable around easily if one antenna failed.
Apparently splitters are pretty good nowadays but they used to be pretty awful, so maybe you have one of the terrible ones.
Are you saying that there is a particular brand of splitter that was manufactured poorly? Splitters have been around since the beginning of RF. Dual splitter w/o amp included is 3 dB loss. Been that way since splitters have been around. Can you be more specific on this?
If you install a new antenna, I suggest you install one tuned for the AIS frequencies. It can still be used in a pinch for generic VHF but will give better performance for its primary purpose. AIS-B is a puny signal (2 Watts) and needs all the help it can get...
I've found my problem. Duhhh. The Factory and or Dealer never installed the splitter. The AIS cable connector is not terminated to anything.
Frustrating. I probably should have noticed this sooner but I've not really needed it. Now that I have started taking notice it definitely didn't seem right.
I hope you get some money from the dealer for the missing splitter. That is not a super cheap piece of gear.
Since you have the opportunity to buy what you want. I wholeheartedly recommend the Vesper splitter.
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