Re the water coming in, yes it does, big time unless you are very quick, you need to have either the end cap or a dumy plug ready to go. As soon as you pull out the sender unit with one hand be ready with the cap / dumy plug in the other. You'll probable get hit in the face with a jet of water but it's a small price to pay in not having to lift the boat out. You'll probably have a couple of pints of water to clear up after.