Vesper AIS: Why does Defender ask this question?

[Jerry Woodward]

Getting ready to pull the trigger and buy the Vesper XB 8000 from Defender. Upon checking out, Defender has a special form to fill out. The first section asks for the MMSI number and call sign and name of vessel. That part I understand; they need to program the MMSI into the AIS. But then they want to know exactly where the GPS antenna is mounted on the vessel: distance from the bow, stern and both rails. I presume this is important to program into the AIS for the anchor watch alarm, but this seems like a stupid question because the XB 8000 comes with its own antenna so by definition it is not yet installed on the vessel. I don't yet know where the antenna will be but these numbers are required entries on the form. What am I missing?

[svlamorocha]

Uncle Sam is here to help and he believes you are not trustworthy enough to program your own AIS as "aliens" do.
The measurements are necessary to program the formula that converts the position of the AIS's GPS antenna into the position of the boat, which will be broadcast by the AIS device.

[svlamorocha]

If you want accurate transmission you will need to set the antenna position now or find a way to change that setting later. At least in some units it is easier to change those settings than the MMSI.

[Dsanduril]

We have the watchmate 650 and can change the x/y dimensions of both the boat and the antenna location at will. It is really close to meaningless on a 40' boat, but on larger vessels it can make a big difference in how you are presented to the outside world (is the signal you receive the bow, the stern, or the bridge of that 300m ship?).

Per the FCC, changing the MMSI is much more difficult (but possible with the Vesper products), but dimensions are easy, so just give Defender your best guess.

[Training Wheels]

Check out milltech marine.

[SoonerSailor]

You can change those dimensions on the XB8000 using the vmAIS software from Vesper. No worries.

[CCR2580]

You can purchase the Vesper XB8000 direct from Vesper. Look on their website, it might be cheaper!

You'll like all the features of the XB800!

[joezzz]

1st off buy from Milltech, much, much better pricing.
I did, very satisfied with there service. Also all of the accessory items are available
Vesper VHF antenna, GPS antenna (mushroom), splitter for connecting to your VHF and extra long USB to mini usb cable for easily connecting to your laptop for programming....and its waterproof.

[S/V Alchemy]

Anyone know if I can buy from Milltech to ship to Canada. I already have a "real" MMSI...but it's Canadian.

[joezzz]

The MMSI number is a unique ID regardless of the vessels registry.
Go to Milltechnmarine.com.
The do international shipments
But you are responsible for all import fees, taxes, etc. and mus be handled by you.

[rwidman]

The location requirement is for the AIS transmitter so the transmissions will show the exact position of your boat. This may seem silly for a 30' boat but it's not so silly for a 300' boat. The law (in the USA) has no exemption for smaller boats.

As a practical matter, the AIS police will not visit your boat tp see if you gave an accurate location when you bought the unit so a guess is fine.

[Jerry Woodward]

Joezzz and Training wheels, thanks for alerting me to Milletch Marine. For the XB 8000, splitter and antenna it is almost $100.00 cheaper than Defender. Their base price is better, then they apply an additional discount when you go to the shopping cart . Good to know I can reprogram it if I need to. But as others have said, on a 32' boat, it probably doesn't make much difference. They only want it rounded off to the nearest meter. I'll just tell them where I think it will go and be done with it.

[a64pilot]

I think the antenna position may be used also for the anchor alarm

[OZwingle]

Setting the antennae position also sets the length and beam of the boat, rounded to nearest whole meters. This can be changed, or better, corrected using Vesper's vmAIS utility software, as previously mentioned. Free to download and install on your laptop. It can connect via Vesper's wifi. You need the USB connection to change the password.

On small yachts, say less than 60' the antennae position doesn't affect accuracy much. But, AIS class B does broadcast your vessel LOA and Beam - which is very useful information to other vessels seeing you on AIS. So setting these dimensions correctly makes the most of AIS for all.

PS: The setting in vmAIS is clearly obvious...to the programmer. And not explained well in the manual. The two LOA dimensions sum to total LOA. If your Vesper GPS mushroom (NOT the VHF antennae) is on the stern rail, then the second entry is -0- and the first entry is LOA in meters. Split LOA between the two entries to "place" the mushroom correctly on the boat. Same goes for Beam. You can enter in feet, but it records in nearest whole meters.

Otherwise the XB-8000 is very good. Best of luck.

[Hyrdflyr]

Milltech is one of the best vendors I have ever encountered. They are always glad to help.Call them anytime you have AIS questions.
Cheers,. Hyrdflyr