A mooring apparatus for mooring first and second vessels, (1, 7) together in a heavy seaway ofFshore is described. The apparatus is for tandem mooring using soft yoke technology. The apparatus consists of a rigid arm (2) with a longitudinal axis and first and second ends. The arm is mountable to a first vessel (1) so that its longitudinal axis is substantially parallel to that of the vessel (1) and is rotatable about a substantially horizontal axis (3) which is substantially perpendicular to the longitudinal axis and is located between the first and second ends. A tension member (4) is pivotally mounted to the second end of the arm (2) and can be connected to the second vessel (7). A ballast weight (8) is moveably mounted on the arm (2) and can be moved longitudinally along the arm by a drive means (9). Actuation means (10, 11, 12) is pivotally mounted to the first end of the arm (2) and controls rotation of the arm (2) about the pivot axis (3) Provision of the moveable ballast weight (8) allows the second vessel (7) to be connected to the apparatus with relatively small connecting loads. However, once connected the ballast weight (8) prevents the yoke masses being excited due to motions of the second vessel (7).