VHF and AIS are complementary systems that are best packaged together - that's because AIS transmits on VHF bands. Seawind offers two options to handle both AIS and VHF. The B&G V60 integrated VHF + AIS, and the Vesper Cortex VHF/AIS. What's the difference? Many sailors “have AIS” but it’s simply an AIS receiver – they’re receiving AIS data and can therefore see targets on screen – but they’re not actually transmitting their own data. Other AIS users can’t locate them and can’t call them – as if walking around with your phone on silent. Both of the Seawind options ensure you have a transponder - you're sending your vessel name, location, direction, MMSI number and receiving the same information from others around you. This is really useful in heavy shipping lanes or equally when sailing in company with other yachts.
The B&G V60 is a "Class B" AIS transponder. That means that with this system you are sending and receiving data, but the data broadcast can in unusual circumstances be lost or overwhelmed by more powerful senders in the vicinity. Situations where that might occur could be the Solent, Sydney Harbour, or even the Chesapeake where container ships and cruise ships with powerfrul transmitters can drown you out.
The Vesper Cortex radio is a “Class B+” transceiver. It has a little greater transmitting range than the conventional B&G V60 (approximately 25km vs 20km). However the software behind the unit delivers a system to avoid being overwhelmed by other powerful transmitters. In Class B+ transceivers the unit not only broadcasts your location, but also the time of the next transmission. So for example if the unit is broadcasting once per minute at 45 seconds past the minute, the other B+ or higher units in the broadcasting range will not transmit at that moment. The system allows a for everyone to broadcast at a moment of low chatter.
The VESPER integrated AIS/VHF is software driven. This adds a potential area of unreliability. It gives greater functionality, but all of the extra functionality comes through ongoing software development. The good news is that it future-proofs the product in many ways, but some sailors will still be more comfortable with a more conventional VHF/AIS such as the B&G V60.
Each black triangle represents an AIS transmitting vessel. Those in bold are "dangerous" as calculated by the plotter. AIS data can become "cluttered". Imagine how many AIS devices are transmitting in the nearby vicinity of the device shown here.
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