You will need two batteries for solar e-boats,otherwise one will do (but you will need a mains charger).
If there is a possibility that your battery will be charged in low temperatures, choose NOVEL series batteries which Incorporate a smart Battery management system, that not only shows the actual battery temperature, but also disconnects charging when the temperature is below or above the preset parameters, protecting against accidental charging when outside recommended environmental range and without needing any external charge controllers.
◆ Longer life compare to lead acid battery
◆ Up to 60% weight saving
◆ 100% usable capacity
◆ More energy with 1/3 smaller size
◆ Less than 3% self discharging
◆ Built in safety protection
◆ Zero maintenance
◆ Easy installation
◆ Quality guaranteed