5″ KP-25A AIS transceiver

  • Class B+ SOTDMA AIS transceiver built in (SOTDMA is the same technology as used by Class A vessels)
  • NMEA2000 data (also NMEA0183 and RS422)
  • Free chart for entire UK and Ireland, France and Netherlands (any other region can be substituted)
  • Sunshine viewable 800 x 480, 1000 nit screen
  • IP66 water protection 



3 in stock (can be backordered)

KP-25A with built in Class B+ AIS transceiver

All Onwa AIS products have a Class B+ AIS transceiver. Class B+ is the later version of the original Class B two Watt system but having five Watts output and using SOTDMA transmitting technology (Class B is CSTDMA).  SOTDMA is superior to Class B CSTDMA, not only in being higher power, but also in enabling a transmitting vessel to access a transmission slot in the AIS system even in AIS crowded waters. Class B can reserve a slot but if the AIS system is in heavy use the slot is not guaranteed so it may not be able to transmit until a slot is available. SOTDMA also has an advantage in that the transmission is sent more frequently if the speed of the vessel increases which is highly desirable for high-speed craft such as a RIB.

Features of the built-in KP25A AIS transceiver:

  • AIS targets overlaid on the chart
  • Class B+ SOTDMA (same technology as Class A) with guaranteed time slot allocation and transmission rate based on speed.
  • Receive sensitivity = > -123dBm (2 channels)
  • Transmit power      = > +36.999 dBm (1 channel) 5 Watts
  • User adjustable CPA and TCPA alarms (CPA = closest point of approach, TCPA = time to CPA)
  • Vessel list shows a list of all AIS vessels transmitting within reception distance selecting any one will show other vessel details including: Vessel name, MMSI, Position, COG, SOG, vessel size and its distance away from your own boat. Note that any vessel calculated to be on a collision course and being inside of CPA or TCPA boundaries will trigger an alarm alert on chart screen and also in detail on the AIS screen.
  • AIS target tracking, selecting any vessel enables tracking of that vessel, up to 10 vessels can be selected.

KP25-A is the latest AIS equipped 7-inch model from Onwa Marine, release date February 2024. Improvements over earlier models include: a new and faster processor for use with the ever more complex charts now available. Brighter screen (1000 nits) for those bright sunny days and NMEA 2000 data but retaining NMEA0183 for compatibility with 0183 equipment. KP-27A has a 24 month warranty provided by AVES Marine Ltd, UK Distributor for Onwa Marine Electronics since 2014. All warranty and technical support is UK based.

  • 1000 nits brightness 
  • 800 x 480 screen resolution
  • NMEA2000 data
  • NMEA0183 data
  • Water protection to IP66
  • 12000 User waypoints, 30 routes
  • Worldwide tidal data information calculated from GPS position/Date/Time
  • Alarms: Anchor drag, XTE, arrival, speed, proximity waypoint, voltage
  • Charts: Compatible with Onwa K-chart V2 and 3.2, Navionics +, C-map Max
  • Celestial: Sunrise, Sunset, Moonrise
  • Charts:  Comes with FREE Onwa K-chart for the UK and Ireland (covers Northern France and Holland as well). If you are buying for use in Europe or beyond, Onwa have a chart for your area which can be substituted for the UK chart. Can use Navionics + chart or C-map max chart

        K-chart3.2 River Medway, England                                    K-chart3.2 Spithead, England

K-chart 3.2 example image Spithead


GPS. Puck type GPS aerial included, can be used below deck in a GRP boat provided deck material does not attenuate satellite signal unduly. 

AIS: an AIS aerial is needed for transmission and reception of AIS


External KA-07 GPS with 10 metres of cable, choice of surface or rail mounts.


Click to see external GPS

AIS aerial: choice of flexible/stubby or stainless whip. Flexible/stubby is particularly suited for low level mounting where a whip type may be vulnerable to damage by crew or the deployment of lines. Aerials we supply are specifically tuned to 162mHz the frequency of the two AIS channels and we use low loss RG8X 50-ohm cable which we cut to your specified length. Cable can be supplied with two high quality PL259 connectors fitted or with one only which greatly facilitates installing the cable though tight spaces or a deck fitting. If you choose one end only fitted, the free cable end is prepared using a professional cutting tool so that the second connector can simply be screwed onto the cable and the centre tip soldered.

Glomex RA111AIS

Click to see Glomex stubby AIS, if Whip aerial required please call



3 in stock (can be backordered)

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