To the best of my understanding of basic water physics...
As long as there are sections/pockets of the boat that are isolated from the water, the body of water the boat is in can only rise as far as its own level in the boat...if rain water can fill the isolated sections, and it becomes enough to swamp the boat, then it could sink...that is one reason to have a bilge pump connected to a float switch directly to the battery, although if it runs long enough trying to keep up with the water coming in, it could drain the battery and stop working...
This was a sketch I made showing how a live well in a boat that is open directly to the body of water will only fill to the level of the body of water...as long as the rest of the boat stays dry...
In the sketch above, if rain water is able to fill the area in the hull that is isolated from the live well and the bilge pump cannot keep up, it can sink...
In a self bailing deck, my understanding is that the rain water will become part of the body of water as long as the self bailing feature of the hull does not become plugged/blocked or clogged preventing the rain water from escaping the boat and the remaining water-free air chambers in the boat remain intact and relatively dry...
Similar to this sketch I found...the image won't load, but here is a link to it...you might have to copy and paste or if that doesn't work google "self bailing" "Images"...
https://www.google.com/search?q=sel...rentPage%3DshowAll%26module_id%3D232;1000;720
Sorry, not exactly a very scientific explanation but its the best I can do...:redface:
eep:
