I agree it’s amazing how much water will come in around the rudder shaft. Pull your back seat look underneath the gas tank look at the router assembly . If there’s a great big nut may be about an 1½ inch. You could tighten it about one turn and see if that helps. You might also need to change the packing that Dan spoke about. If there is no big nut to tighten you might need to change the seal that’s in the router port. Not a fun job ,it’s hard to get to. Good Luck