if hull is not leaking after putting water in it with the garden hose in your driveway, i suspect your older foam in your hull is absorbing rain water. you will pump the bildge dry and some time later have to do it again? foam could be bleeding out more water and the process repeats over again. try to take a core sample of foam from somewhere in the rear of the boat to check for water content. if it is really bad the hole left from the sample will fill in with water just like a hole in a watermelon. good luck and let me know. john