The 88 foot long two-masted schooner Wendameen went aground off Great Diamond Island in Casco Bay, Maine.  The vessel was passing by the north side of the island during low tide when it grounded.   The 49 passengers on board were transferred to the Portland fire boat and the Coast Guard rescue boat.   Reports state the vessel will be refloated on the next high tide.   No reports of injury or pollution being released.  The Wendameen had went aground previously on June 4 when it struck a charted wreck.   The incident is under investigation.