In order to determine how many watts you need for your boat stereo, you'll first need to consider the size of your boat and the type of sound system you want. For smaller boats, a basic sound system with two or four speakers will be sufficient. However, if you have a larger boat or you're looking for a more powerful sound system, you'll need to consider amplifiers and subwoofers.
The next thing to consider is the type of music you like to listen to. If you enjoy listening to loud, bass-heavy music, then you'll need a stereo that can handle those types of sounds. On the other hand, if you prefer softer music or if you only plan on using your stereo for background noise, then you won't need as much power.
Finally, think about what kind of budget you have for your boat stereo. There are stereos available at all different price points, so it's important to find one that fits within your budget. Once you've considered all of these factors,you should be able to narrow down your choices and find the perfect stereo for your boat