Rob...when you say it leaks I assume you mean the centerboard trunk which holds the centerboard has cracks in it and is leaking. This is probably due to hard groundings over time. Can you physically move the trunk by rocking it side to side and can you see where the cracks are? The easiest thing to do is re-fiberglass around the base of the trunk after cleaning it our and widening any cracks you've found. West System epoxy can supply the materials and instructions you need.