should I antifoul echosounder transducer?

[Piers]

They sell a special antifouling paint that does not attack the face of the transducer. I have always used it.

http://www.westmarine.com/buy/mdr--transducer-antifouling-paint--128225

I always pay into the bank of good karma and wander round the yard offering to paint anybodies transducer on the basis that I will never use up my pot.

I, too, have always used this paint. It's water based. I believe the issue to be 'normal' anti-foul can damage the surface of the depth sounder. And, yes, you're right - the pot lasts years!