You got it. That's the best way to know FOR SURE for YOUR boat.
Next, check how much lower the drain scuppers are below the floor. Meaning, whether or not the scuppers are partially/fully submerged is not the limiting factor to draining - it's the resulting height below the floor. HOWEVER, if they are submerged, then you do need to keep a REALLY good eye on their integrity and also the hose.