Abstract: In an offshore mooring system for seagoing vessels, a mooring hawser formed nto a loop is resiliently fastened with both its ends around a tower head of an offshore tower. The hawser is kept in readiness beneath a jib of the tower and is spread open by spreading lines running over spreader arms. Spreader blocks are provided for lowering and slackening the spreading-lines so that the hawser can be laid around a bitt on the vessel. The bitt is provided on the forecastle of the vessel on a cradle or platform for bringing the bitt to a position ahead of the bow of the vessel, so that the bitt is positioned substantially beneath the hawser which is spread open for mooring. Mooring operations are made possible by the invention obviating undesirable manual work, even in high seas and rough winds.