Have a scan through the RYA web site where you can down load their current list of PY's for both dinghies and yachts. Be prepared not to find the boat you are looking for - before the RYA will present an official PY they need a selection of results to base thier value on. If this is the case then email them and ask them to recommend a trial number - this you can take to your club sailing committee where they will apply modifications to the value based on the configuration of your boat (roller reefing or not, fixed or folding prop etc..)