installing a transducer

What is the boats deadrise angle? Probably 18-20 degrees, so 20 degree would be the likely suspect. All of these are made by Airmar. I'd call them to get a read before cutting holes. -->> https://airmar.com/

 

I just went through adding another to my boat. The 0-15 degree needs a flat surface and you aim the arrow toward the keel (centerline). If you go with a 15-30 degree, the mounting surface needs to have an angle or it will not be flush. I had to move both of mine as this was an issue during my install.

 

20 degree. Here's an Airmar B60 20 degree installed in a 2000 290AJ.