I too have lake water coming up into the bilge, about 7 gallons in four hours, (1 3/4 gal per hour). (About an ounce a minute), essentially a small leak. I plugged the centerboard uphaul inter hull gap, (see link)http://www.bobhunkins.com/mt-archives/DS2CBTLK_100.pdf
ensured that the hull/deck joint was well sealed, and tightened and siliconed the nuts on the centerboard pivot bolt. I can't think of any other place the water would be coming in, but the first thing I am going to do is retighten the nut on the pivot bolt, and re-silicone around it. If that is enough, I will purchase and replace some rubber washers/gaskets from the daysailer parts dealer in the parts and accessories section of the home page of this forum.
I think this is a design fault, because it is reported quite often, although there are some owners who report a totally dry bilge, to the point of dusty!