J/30 Class Association Forums J/30 Forum One Design Class Rules Standard & Optional Equipment Interpretation Discussions

The class rules in the J/30 Basic Specifications section actually shows a 3/4" shaft.

Propeller: Standard propeller is folding two-bladed Martec Design Number 23780 - Right Hand, 14 inch diameter, 14 pitch elliptical for 3/4 inch shaft.

Many boats were delivered with a 1" shaft because some new owners complained of shaft vibration, and extra margin needed for added horsepower with a 2GM20. Realize the expense includes replacing the prop, strut, shaft, coupling and cutlass bearing if a change is made.

Some history discussions for this are on this thread