The author marks the location of speakers and electronic components on a scaled drawing of the deck to determine the gauge and quantity of wiring needed, and the type, size, and placement of the subwoofer enclosure.
To make weatherproof electrical connections, the author starts by joining marine-quality cable with heat-shrink butt connectors.
At the heart of the sound system is a Rockford Fosgate Prime M600 marine-grade 5-channel amplifier, paired with a matching Bluetooth receiver. Since the components operate on 12-volt DC power rather than 110-volt house current, a converter/charger sized to match the amp is also required to power the system.
The author installed speakers that were designed for mounting on a wakeboard boat tower. The speakers are rated for full exposure to weather, with high-density polyethylene enclosures, and are equipped with adjustable aluminum hardware so they can be clamped to round rails.
To keep the woofer dry, the author built a waterproof enclosure for it with Nylosheet, a waterproof material made of fiberglass and recyled carpet (nyloboard.com).