Modify a NMEA183 sentence in Signal K (Solved without needing to modify)

[Jodel]

Hi,
I have a Stowe Databox connected via a NMEA to USB adapter to a PI 4.  All the NMEA sentences, except for one, are standard and display correctly in the data browser in Signal K and in the dashboard in Opencpn.
The non standard sentence is DBK.  It has an additional character in the first position.  Either an "A" if depth is live/correct or a "V" if it is last valid depth.  I need to strip the first field containing this character out of the sentence.
This seems easy enough if I ignore Signal k and run the serial input directly to Opencpn as the NMEAconverter plugin can modify NMEA sentences.
However I would like to stream all data through Signal K.  Is there a simple way to see the raw NMEA 183 data that Signal K is receiving and to modify it before SignalK parses it?
I see an option for Data fiddler.  Could  this be used to remove the first field?
Will I have to learn Node Red !!
Jodel

I have worked around the problem.  I manually added direct connections to Opencpn in its connections tab and it reads the DBK sentence correctly. So now I have nothing going through Signal k, but my next step will be to route all the NMEA from  Opencpn to signal K .
This seems to be the reverse of the thinking in Openplotter but so far seems to work better for me.  Any disadvantages to this approach?
Jodel