Why do most smaller personal boats have holes that you need to plug before going in water?
I assume since we don’t permanently plug them since water inevitably gets in during operation that needs to be drained. Where does that water come from? Why is it designed that way?
In theory, if a boat that has removable is in water long enough without coming out to drain, would the boat sink because of the water that came in during use?
In: Engineering
When it rains, water gets inside of the boat. It has nowhere to go. If you’re storing it on land (which is common for smaller boats), you can just leave the plug out so water has a place to drain. Leaving it plugged means you come back to a stinky boat with a lot of mosquitos after a big rain.
Bigger boats tend to have pumps to deal with this since water can get in a lot of other ways too, it’s harder to deal with manually, and they don’t spend a lot of time on land.
It is easier to drain the water while on land with a plug than turning the boat over.
Water comes from the rain and splashes – that is the majority. Also engine cooling leaks. Leaks of all the fittings.
Boat on water with no maintenance will sink in months due to the rain or splashes. Bigger ones could last a bit longer, maybe years.
Smaller boats have drain plugs because the assumption is they come out of the water. So draining them or washing them and draining is easy to do. It’s not designed for use while on water. This way you don’t need pumps.
You’re in a vehicle with a giant opening on top. Water splashes, people get wet and get in the boat, anything can happen. That hole is far more effective at draining the water than turning the boat over and draining it that way, which is how you clear water from a canoe, kayak, or another small boat you can pickup easily.
Depending on the size of the boat water may come in over the stern or the sides, or it may seep in around the plug or through seams in the hull. Most boats have some type of foam under the floor and in the side walls that will absorb water, making the boat ride lower which may make it take on more water. So the plug is pulled after a day on the water so everything drains out, including water in the foam.
Forgetting to install the plug will cause the boat to sink right there on the dock, but if you can get the engine started and take off forward fairly quickly it will draw the water out the stern. It works by some physics principal that I do not recall.
That much water is not a normal occurrence. But my dad’s ski boat (which is basically a turbocharged 464 that happens to float) has enough power that if you gun it at just the right moment as a big wave comes, it can jump completely out of the water. After figuring that out, he quickly found out that if another wave is at exactly the right (wrong?) distance away, the bow will go right into it and swamp the boat. He was very glad to have a drain plug instead of having to figure out how to flip it over to drain.
The water comes from splashes, drips from ores, and rain, could be anything. This water needs to be removed for reasons such as the corrosion of parts that aren’t designed to be under water; preventing mould / algee growth from areas being left damp; or simply keeping your feet dry.
Boats are designed this way for simplicity and cost. Large boats have pumps to remove excess water automatically, but for boats and other small watercraft that aren’t designed to stay in water permanently, it is cheaper to just unplug a hole when done and reduces the complexity of the boat.
For your last question, a boat probably wouldn’t sink if in use for too long as the person(s) on board could deal with the water. However, if nothing was done about it, then it would depend on the design of the particular boat. What would happen as some boats are only buoyant because of the shape keeping water out, but some are constructed from materials that would still be boyant if filled with water.
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