You can test if a transducer would work through the hull using either a toilet bowl wax seal or a Ziploc bag with water inside (big enough that you can put the transducer in the bag with the water there. The Ziploc idea is better if you are trying to find the right location (you can move it around easily).
I would not use a transom mount transducer inside the hull, but a through-hull one should be able to work fine. It might be tricky to make sure that you are pointing down, though. An in-hull transducer (AIRMAR P79) might be your best bet (it is almost infinitely adjustable).
I would not use a transom mount transducer inside the hull, but a through-hull one should be able to work fine. It might be tricky to make sure that you are pointing down, though. An in-hull transducer (AIRMAR P79) might be your best bet (it is almost infinitely adjustable).
