More info needed, but
You did not exactly specify what water was coming in. Sea water or fresh water from rain? Nevertheless, based upon your description, I think the tube you mentioned is possibly for the cock pit drain holes located at the front of the cockpit floor. But I am not sure. Early C-22's and C-25's have the cockpit drains on the cockpit floor forward just below the cabin opening. These attach to tubes that run down to the keel to a seacock where they drain out. Again I am not positive if I am on the right track here or not. Nevertheless, I think the tube you mention should be attached to the sea cock and as it is not, water from the cockpit is draining out this tube. I hope this helps, but I really do not know if it is correct or not. Nevertheless, C-25's with swing keels do not come with bilge pumps nor should they require them. If water is coming in, you must direct your efforts at the source of the leak and not waste time and money on a bilge pump. This means taking all the topside fittings off and resealing with a good sealent, checking the window seals, checking the hatch and lazarette cover seals, etc. There is an outboard, so no propeller shaft seal to worry about. The keel lock down bolt should be covered with a good marine grade grease to prevent leakage there.
