Ganhardine decides to set sail for Tintagel to bring Iseult of Ireland to the wounded Tristram .
They agree that Ganhardine will hoist a white sail if Tristram returns with Iseult on board , and a black one if Tristram returns alone .
Ganhardine decides to set sail for Tintagel to bring Iseult of Ireland to the wounded Tristram , and they agree that Ganhardine will hoist a white sail if he returns with Iseult on board , and a black one if he returns alone .