Milltech Marine AIS Support

Top Support Questions (See more FAQs here)

Q: Will this (brand/model) of AIS work with my Chartplotter?
A: All of the AIS Receivers and Class B AIS Transponders offered by Milltech Marine (except the Smart Radio SR161 and SR162, and the Comar AIS-2 USB, which are intended for connection only to computers) will work with any AIS-enabled chartplotter with NMEA 0183 RS422 input (nearly all current-model plotters). To be sure, check with the chartplotter manufacturer or refer to the manual (in the product specifications, look for NMEA 0183 RS422 output and AIS capability.) More...

Q: How much will my order cost to ship?
A: The quickest and most accurate way to check shipping cost before placing your order is to enter the selected products and your ship-to address into the shopping cart. Then go to "Checkout" and review the "Shipping Options." This will allow you to review all available choices for shipping carriers, services and costs for your order, without committing to the purchase.

Q: What is the best antenna installation for AIS?
A: It is the same as for a VHF radio antenna: Generally, we find a single length of

Cable Length	Cable Type
< 10 m (30 ft)	RG58C/U
> 10 m (30 ft)	RG213/U

coax is much better. As the length gets longer, you should consider thicker coax. (See table at right for general guidelines.)

On a sailboat, the masthead is typically the best location. This is due to the fact that the antenna is both high and free of clutter that cuts down on reception.

Make sure that there are no other antennas on the same plane as the AIS antenna. We have found having another stick near the AIS antenna can reduce the range by about 60% or more.

Q: Should I use a dedicated antenna for AIS or an AIS/VHF radio antenna splitter?
A: Antenna splitters simplify installation and reduce cable runs. Signal loss is minimal (<3dB) and is far outweighed by the advantages of an antenna optimally located at the highest point available (sailboat masthead, power yacht cabin top or arch).

Splitters are available for either AIS Receivers or Class B AIS Transponders. Splitters designed for use with AIS Receivers are not compatible with AIS Transponders.

Q: When using a Class B AIS transponder, can I turn transmission of my vessel information on and off?
A: Yes, both the Comar CSB 200 and the ACR Nauticast-B allow the installation of a manual switch for turning transmission on and off.

Q: Even though my Class B AIS is transmitting, why do some vessels with AIS not see my vessel name?
A: AIS information is sent in different message types. The MMSI, position, course and speed are sent frequently so this information shows first and will show on all AIS receivers, Class B and Class A. The Class B Static Data Report, or "Type 24" message, such as name of the vessel, type of vessel, destination,etc., is sent less frequently. This information takes longer to show on AIS displays and will not show on older Class A devices.

If a Class A AIS-equipped vessel does not see your vessel's name after a reasonable period of time, is typically due to AIS hardware or software on the receiving vessel that is not current. Many SOLAS vessels were outfitted with Class A AIS before the Class B Static Data Report format was defined. This means that they may not see your name, but they will see your vessel as a target with MMSI number, position, course and speed.

Q: Can I use my existing GPS for my new Class B AIS transponder?
A: Class B AIS units will not accept any GPS NMEA data input from an external receiver. The specifications for Class B AIS requires a discrete and dedicated GPS system because the unit is transmitting the vessel position and must synchronize with the AIS network. The CSB 200 must use its own internal GPS receiver and a compatible external powered LNA (Low Noise Amplifier) GPS antenna (such as the AMEC AGGRESSOR-111-C ).
The Comar CSB 200 connects to other devices via the standard RS-232 (using a USB-to-Serial Adapter if necessary) and RS-422/NMEA ports. This sends both AIS and GPS data, so it may be possible to use the GPS data from the CSB 200 for one of your other systems (e.g. DSC VHF radio), eliminating the need for other GPS systems. Unless you are experienced with installing marine navigation systems, it might be best to consult with a qualified marine electrician regarding set-up.

Q: Can large vessels with Class A AIS filter out Class B AIS?
A: No. At minimum, your class B transmissions will always show up on the Class A display as a target. Some Class A vessels will "filter" the display so that only the Class B target symbol shows and must be cursored over to display alphanumeric information (MMSI, speed, heading, etc.). They do this to differentiate between SOLAS Class A vessels (very large commercial vessels with slow rate of turn) and smaller Class B vessel