Through the hull is still the most common way to install a transducer. "No hole" inside-the-hull transducers can be less effective, especially in terms of signal loss and decreased depth range. But commercial fishermen have started connecting their fishfinders to a new breed of 1kW, 2kW, and 3kW inside-the-hull transducers with remarkable results. Airmar (www.airmartechnology.com) has versions of its M260, R199, and R299 transducers that complement many common fishfinder models. Garmin, Humminbird, Lowrance, Raymarine, and other companies make transducers that can be epoxied in place inside the hull and are effective in transmitting acoustic energy through fiberglass. Several versions have adjustable liquid-filled mounting bases to compensate for a hull's deadrise angle.