What kind of sailboat was featured in Nim's Island?

I don't know the specific design, but it was wood, about 32', and the designer who developed that general type of boat was Colin Archer. His boats are double-enders (i.e., pointy stern), have transom-hung rudders, and are generally of medium to heavy displacement. The type was originally developed for use as rescue boats and are famous for their performance in heavy weather.

Probably a boat called Shona built 1920's, designed Australian Walter Weeks - great looking boat isn't it.