When I purchased 1728 I was told that the front beams leaked :(, being a novice to the class I was not too keen to remove the bolts from the front beam and silicon them up . So I repaired all the other areas first, rudder bolts, hatch's , etc only to find that it still leaked. So armed with information from this site I removed the bolts and siliconed them up . This fixed the leak........for 2 weeks . I am now now chasing up all the other areas again and now you tell me it could be the centre board case's .