This releasable rubber joint / swivel for tiller extensions is mounted with an aluminium pin only.
The pin is kept in place by a piece of heat shrinkable tubing.
To remove a joint: simply cut off the tubing and push the pin out.
The joint incorporates a fibre core molded up in the centre.
The fibre core will avoid complete failure should the rubber tear which allows you to finish the race.
The distance between the mounting hole centers is 32 mm.