Tks for suggestion Tiger,
Few months ago I already bought new Raymarine transducer and carefully put antifouling on it, but it become again blocked after some time even I am using my boat at least once a month,
Its not a problem to clean transducer. but I don't like a mess of salty water doing it in the water.
I have already B&G Vulcan plotter in the system so connection to NMEA might be possible.