Connecting marine electronics, straight to the 12 volt battery can have consequences. DC/DC Converters can provide stable, regulated output When you crank the motor, battery output voltage can sag down to as low as 6 volts! this is not good for electronics. Installing a converter (buck/boost converter), power regulation can be maintained for sensitive electronics. I found a low cost device that looks suitable for small loads (VHF, GPS, Fishfinders, LEDS) http://www.powerstream.com/dcdc.htm This small unit cost right at $50.00 usd. All this little unit needs is a weatherproof enclosure.