When you are designing a system for a boat, motorcycle, or a side by side offroad vehicle, the two main things to consider are:
Is this equipment going to last in the elements that my vehicle lives in?
Is this equipment going to work properly with my vehicle and its charging system?
Most boats, motorcycles, and offroad vehicles spend the majority of their lives in very harsh environments. Even if they don't see salty roads or salt water, even if you live in Yakima, WA where I do, they can be subject to incredible amounts of moisture, UV rays, dirt, and sometimes humidity that you normally would not get inside your car or pickup. These are things to consider when choosing your new audio equipment.
Also, the charging system and batteries on a boat, motorcycle, and or side by side vehicle are usually very small compared to that of a car or pickup truck, so you need to choose equipment that is more efficient and will not draw as much power down. On a boat, even consider installing a secondary battery and isolating it away from the starting battery. I can easily do this for you BTW at Franks AudioMotive install shop in Yakima, WA.