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Vesper marine ais watchmate


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Ive bitten the bullet and purchased one of these units i thought i would just use a 30 dollar aerial splitter fron burnsco but instructions say to buy one of their units for 430 bucks.Does anyone know how much difference a cheap one would make,would it still work?cheers

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If you are talking about the Pacific VHF/AM/FM band splitter then it will not work. You may get lucky and find that a strong local VHF/AIS signal may get through the AM/FM band pass filter but it will be a very weak output signal and unreliable.

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WV, sorry, but your approach is why some report AIS is useless. Please either spend the time to research online what you need, rely on a local specialists advice, or ask on crew.org!

Ais does not use the same frequency as your vhf radio. The antenna should be designed for ais, and dedicated to that task.

Alternatively, and for a small loss in efficiency, you can use a quality, powered ais antenna splitter that intoduces gain to help compensate for the loss in the splitter. Vesper’s splitter is an excellent example of this. Navico’s one is good as well. Neither of them is cheap (3-4 hundred) but they work well.

A cheap basic splitter wont work properly and can limit or prevent transmission or reception for both your vhf and ais.

The vesper ais units are, IMO , the best available, with great support.

Yes, I do sell them, but I would have told you this on here regardless of whom you chose to buy it from...

If in doubt about something boating related, ask on here before making a decision, some of the members have lots of knowledge and experience, it’s free to ask, and can save lots of $ and or anguish!

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Thanks IT my vhf aerial is on top of my mast if i use that just for the ais surely it cant get any better? I have a hand held i can use for forecasts and transmitting so thats ok i only use it for forecasts mainly anyway

Well, that antenna is a vhf antenna, not a dedicated AIS antenna, so yes, it can get better than that, but the difference is small, so it’s ok to use.

However, class B AIS is a low power system. It will highlight any antenna issues you have, like age and condition of the coax to the antenna etc. if it’s 20+ years old, the coax is likely in poor condition. How was your vhf signal? Done a radio check with coastguard lately? If you have, and they reported loud and clear, then you are probably ok with that antenna.

Finally though, please consider that your vhf radio in your boat is 25 Watts, with a masthead antenna, and you handheld is likely 3 Watts, with a small rubber antenna. The range difference is substantial. VHF is a primary safety device, and personally I wouldn’t compromise it’s range for an AIS.

IMO you should get a proper splitter, or install a dedicated ais antenna. Ais antennas on the stern rail or on the spreader work fine, and does not effect the vhf.

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What about a separate aerial? If the VHF Antennae is not really the right tuning for AIS, would a proper Aerial be better and surely you would not even have to mount it anywhere. It could just fit in the back of a locker or behind a wall or ceiling lining.

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Vesper sell a the aerial (I think made by Pacific Aerials) which is said be designed to work up to the band's used by AIS.

I purchased and installed one when I had the mast out, have not had an AIS transmitter on it yet, but receives AIS signals ok.

I will need a splitter if I install a tranceiver

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The Vesper marine ais antennas are made specifically for them, not certain by whom. They do 2 main ones, a dedicated AIS one, and a combination VHF/AIS one as MH says.

Wheels, antenna height helps range, so generally higher is better.

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Dont assume everyone has them though. You still need a proper lookout. We had a classic example off Gisborne heading north in June. Ellen on watch said this guys really close. I checked AIS , fishing boat 1 mile away -no drama. She said no he is really close. This debate of course went on for a bit. Poked head up companionway, to see a different fishing boat with net behind about 3 swells away! Lesson of course rely on eyeballs not just all our wizzy electronics. Still rate our new AIS as one of our best bits of kit on board -especially at night to figure out ships and courses. My 2 cents worth.

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We have also found the ships to be really good. A quick call on vhf, and usually they say yes we have you and just hold your course and we will go around you.

It is the fishing boats that tend to like being invisable.

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While that is absolutely true extl, modern radars like the (3g and 4g from navico) use very little power -

3G radars start at about $2500.

Im happy to discuss particular requirements, and provide quotes, and demo's to anyone interested.

Both AIS and Radar are best of course. They are not the same, and should not be considered substitute for each other as some people do.

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