The boat was my new Swarbrick S80 and we were having a great first day with it. Ouch.
It broke cleanly at the spreaders. One explanation is that it may have been the result of 'galvanic corrosion'
caused by the spreaders metal (stainless steel) in contact with the aluminium mast.
Quote " If they are not insulated from each other, it is only a matter of time before it eats through the mast"