Tech HUB


This list of commonly asked questions regarding B&G and A+T Instruments is being expanded month by month. If you have a question which is not answered here please feel free to email us on The list is primarily aimed at systems based on B&G H2000, H3000 or WTP systems driving the displays through the Fastnet bus, but some questions/answers are generic. If your questions isn’t answered here, please send us an email at


Existing B&G H2000, H3000 and WTP plus has a future-proof interface and software design to allow for upgrades to new standards and systems.

Although parts for these are now either not available or in very limited supply, we are able to repair a good number of faults. If the unit is beyond economical repair then a new compatible unit, the A+T MFD, is available here.

We can repair existing H2000 and H3000 systems so with the new A+T displays these can still be used for many years yet without rewiring and changing all displays.

Check the termination resistors are in place; there should be two 100 Ohm resistors at either end of the network both wired between the green and the white wires. These are normally found in the junction boxes. With the system powered off, there should be 50 Ohm resistance measured between the green and white wires in any junction box. The new A+T MFD also has the ability to monitor the network resistance while live on the network.

This is an unusual cause if the system has been working fine previously. Possible other causes are:

a)  A short or open circuit in the network, the former often caused by water ingress


b)   A faulty display on the network, take out these units or leg at a time to determine the faulty unit(s).

  • All PA66 CNC construction, no metal parts to corrode
  • Larger and clearer display digits and reverse display (white on black) for better night use
  • Higher environmental specifications and resistance to water ingress
  • Bluetooth upload of software and ability to store and send sample Fastnet data
  • Internal monitoring/display of temperature and humidity
  • Fastnet bus diagnostic features
  • Ethernet built in for future upgrade path

No. It is a completely new design incorporating everything that has been learned over the last 25 years in terms of requirements and ruggedness/water integrity, so leapfrogging anything in the market today. Digits and displays are clearer, software updates can be incorporated via Bluetooth and Ethernet interfacing is incorporated for future system adaptability. It fits into the same cut-out and mounting holes as the B&G FFD/GFD and is compatible with the B&G Fastnet data-bus; a unit can be swapped out in less than five minutes.

No. First of all, the current B&G processors (H3000 and H2000) are generally very reliable and last a very long time, so replacing B&G displays with the A+T ones (there are two further displays in development at the moment) will give many years of continued performance. Also we can repair these processors if they break or supply refurbished ones.

Secondly, in 2017 we will produce a brain that supports both legacy B&G displays plus all of the new MFD instruments so allowing a piece-by-piece upgrade path rather than throwing everything away and starting again. A key consideration in the design of this will be to use existing wiring where this is expensive or difficult to change.


We have had several reports that B&G H5000 suddenly loses its NMEA2000 depth source, especially on larger systems. We have had the same report for systems running various makes of depth sounder, including Garmin, Raymarine and our own 170kHz N2K compatible depth sounder. Uniquely, we have now updated the firmware in our own depth sounder to prevent this happening.

The H5000 processor alone has at least eleven N2K address nodes. Every H5000 display connected to the system adds at least another node, often several. These nodes are in addition to all the other manufactures devices.

If for any reason another N2K node is added to the system, (however isolated it may seem, such as a crew member switching on a stereo), all the address nodes will shuffle around while the whole system re-negotiates. On large H5000 systems, this can take some time, as well as several power cycles for the new database to be shared between the H5000 processors and all the displays. In the meantime, the boat is without depth!

We are now confident that you will not see this issue with the latest firmware in our own depth sounder.

This can be caused by water ingress on the speed sensor or its connecting cable. Try temporarily disconnecting it from the processor to see if the alarm stops. If it does then the offending sensor/cable is determined and can be replaced.

The most likely cause is a damaged cable or faulty transducer. Replace with a known working one to check this. Also check for being painted over or marine growth on the transducer.

Firstly ascertain if there is a single paddle wheel or two selected with a gravity change-over switch.

a)   Single paddle wheel. Remove from the hull housing and spin manually to check the sensor both electronically and mechanically. Measure the voltage with the black probe of a multimeter on the black wire and the red probe on the red. If this is not between 5 and 12 Volts (system dependant), the control unit is faulty. Now put the red probe on the green wire and turn the paddle very slowly. As the magnet passes the sensor the voltage reading should change from 5 Volts (+/- 1.5V) to 0 Volts (+/- 1.5V) and back again. If not, the paddle sensor is faulty.

b)   Dual paddle wheel. In our experience a good proportion of twin paddle wheel issues are caused by faulty switches. These can be checked by manual selection or direct wiring until the issue is found. We can supply replacement gravity change-over switches which can be found here.

First determine if the apparent wind angle is working properly. Check this ties up with the Windex at a good variety of relative headings to the wind and all around the clock. If there is one wire broken in the mast cable then the wind angle changes, but does not follow all around the clock, but ‘doubles back’ as the relative heading changes. This can also be caused by faulty wind sensor or wind board (in the processor). If the apparent wind angle is working properly then the culprits must be either the compass or speed log. Check these are working properly.

Calibration, calibration, calibration. It is not that difficult if you follow the procedures set out in the system manuals. Even getting some rough estimates or corrections in the True Wind Angle table will start to improve this quickly. Don’t be afraid to put in corrections up to 10 degrees into these tables in some circumstances. We are often at regattas and will help with this if time allows.

Apart from large yachts that take the compass heading from a north seeking gyro, most systems use a magnetic sensor for heading including (confusingly) the B&G Halcyon Gyro Stabilised Compass. Before looking anywhere else, locate the compass mounting and ensure that no magnetic or magnetically susceptible material has been placed close to it (typically tins of beans, spanners, tools, spare parts, hand bearing compass).

Having checked this, ensure that the calibration ‘turns’ have been done recently in the yachts current broad geographical location. The methods for doing this are different in different systems, see individual handbooks for this, also available here.

Finally set in the heading offset needed to get the electronic compass to agree with a recently swung traditional compass or hand-bearer or by taking bearing to a distance point.


Most faults which appear to come from the processor, in the end are traced to sensors, one or more faulty displays or faulty wiring, especially of the Fastnet bus. If all of these have been eliminated then we are able to test and repair H2000 and H3000 processors and their accessories including auto-pilots.

In most cases the obvious casualty is the mast wand and electronics itself. This can be replaced and at the same time it is wise to replace the mast cable which will almost certainly be badly damaged at the mast-head connector. Harder to pin down are more subtle areas of damage which can occur to the processor, particularly wind board and other interfacing functions. If suspect, we can test and repair complete processors. IT is also worth looking out for other apparently unrelated interfacing breakdowns on link to other marine and computer equipment.

Networking issues

Please read our paper on troubleshooting. Fastnet trouble shooting V1.0


We can repair most B&G instruments plus almost any other marine equipment. Please have a look at our delivery address and instructions.