In England one of the great dinghy
designers was Ian Proctor. One of his enduring designs is a 16'boat - The Wayfarer- designed some 50yrs ago. It is mainly sailed in Canada, UK, Denmark and Holland plus a few other countries. It is a One Class Design.
Originally it was designed to be built in Wood with plywood on a frame resulting in a shape with chines. With difficulties of renewable wood and costs it was soon produced in GRP but had to be the same weight to comply with the one design class.
The wood ones always out performed the GRP ones. To improve the performance of the GRP boats they made them a sandwich GRP construction. All the boats had similar hull shapes.
In the end the best helms soon learnt to search for the best condition/latest wooden boat they could find. As they stopped building the wooden boats in 1988 this was considered bad for the class. In 2007 it was decided to make a new GRP boat to be as fast (or faster) than the best wooden boat. To achieve this they had to alter the hull shape slightly.
We did the 2009 Nationals and other competitions and generally found a number of helms in the latest GRP boat were getting results that were better than we expected.
Conclusion - in one design with shape and weight limits a wooden boat performs better than a GRP one. I believe this is because wood is inherently stiffer and faster for any given weight than GRP. Obviously Kevlar or Carbon Fibre would influence this (not allowed in a Wayfarer).
For the 2010 season we have now sold our beloved wooden Wayfarer and ordered one of the newer shaped GRP sandwich construction Wayfarer.
One disadvantage of GRP is that with age they do get heavier as they absorb an amount of moisture while a wooden boat with regular investment (painting/varnish) and drying out during the winter can be keep as new.