I looked through forum and finally bought a hummingbird Piranha max 10depthfinderI'm trying install it as a through hull transducer in the forward section of the boat.Hummerbird allows you to switch transducers if you send them other one.They have several through hull models a flat and angled transducer,I have a 1986 catalina 22should I get the flat or the angled one?They suggest if the bottom angle is more then 15 degree to go with the angle transducer. My boat is wrapped up for the winter and i want to get the right one,Has anyone done this beforeThanks Paul