I just finished the bottom paint on my boat and have the opportunity to clean the outside of the thru-hull transducers.
Is there ever any need to clean them if that are not covered in algae or other growth. IF there is a need to do this, what kind of materials do I use?
No guesses please, buts the facts man!
If they are not covered in growth or barnacles or some other marine life there should be no need to do anything other than a soap and water clean which you most likely did prior to bottom painting.
A coat of wax may help in discouraging algae growth.