FYI, I just purchased a 2220 fisherman 2008 and the only problem i had was with the hull mounted transducer. Depth finder would not work properly.Kept flashing 60 ft all the time and would not register depth. I spoke with the dealer about the problem and they stated that they were having problems with some of the boats with this type mount. They fix the problem by mounting the transducer to the transom.Works great.
I also spoke to the manufacture(Lowrance model LMS 520C) about the problem i had with the depth finder/GPS and they said that the transducer should be mounted with the right adhesive(epoxy) recommended by the manufactor. There should be no air between the transducer and the hull.I guess what I 'm tring to say is that if you mount it in the hull and it doesn't work and try to remove it you will rip the fiberglass. There is no sure thing if you mount it In hull style.The sure thing is to mount it on the transom. As per dealer Mech. They had to leave the transducer epoxied to my hull. I didn't want then to damage the fiberglass.
If you dicide to mount it in hull . Try not to mount it to close to a pump are electric motor. Electrical noise from the motors can cause the sonar not to work properly.Hope this helps.