OHMS law. P=ExI, where P is power/watts, E is voltage and I is current. 5 =14(x) 5 divided by 14. Or just trust me(note my occupation).
If you use the motor for only 20 or so minutes a day, 3 or 4 times per year, it may be OK, but you will still need to charge it fully occasionally. I would go with at least one 15 watt panel from harbor. Get a cheap digital voltmeter and monitor battery voltage when you go fishing. When it gets down below about 12.5 volts with no charger connected, you will need to fully charge it. If you tell me how big the troller is, how long you run it, etc, I can give you more specifics.
