An offshore riser system has riser joints, each having a pin and a box. The pin has an external grooved profile that is engaged by a locking element carried by the box of another riser joint. An actuating ring engages with the locking element to move it into the locked position. A retractable spider supports the string of riser while the new joint is being made up. A makeup tool on the riser deploying floor moves the ring relative to the locking element, causing the locking element to move to the locked position.