If I get a transducer fitted to my boat will it foul the trailer I keep the boat on. How do I avoid damaging it when I launch/recover? I assume it sticks out a bit!
Shouldn't be a problem. The transducer will never hit the trailer because the trailer should only go as far as the transom on your boat and the transducer sticks out past this. It wont get damaged when launching.
Why would you want to start drilling holes in a perfectly good boat!? Glass a tube in the hull under the floor or in the engine compartment, fill it with castor oil and bung the transducer in that......
if you havent bought the transducer, then I d go for one to fit inside the hull. A number of favourite techniques, but the key is to ensure that you locate it above "clean " water under the hull.. ie, not right above something the disturbs the water flow.
Not sure that boat/engine set up you have, but commonly about 1m in from the stern is a good guess. Most people find using some silicon as glue to fix it in place does the trick, simply.
You can indeed use a transom mounted one, and although they must be ok as its popular, seems to me the water is more likly to be disturbed when you start locating it at the back of the boat and near the props.