You can tell the approximate age of a boat by the sail number using the table below. The sail number will be engraved onto the inside face of the rear transom on wooden boats, or found on a blue and white IYRU/ISAF/World Sailing plaque which should also be on the inside face of the rear transom, or on the aft bulkhead. There are a few caveats to bear in mind.
- Data from 1963 to 2000 is from Bell Woodworking or Widebeam and many of these boats were kits, so this is the year the kit was manufactured. It's always possible that the kit was stored, maybe for years, before being built.
- Since 1990, IYRU/ISAF/World Sailing have issued sail numbers via the plaque. Licenced Builders can buy plaques (and thus sail numbers) in batches. If a builder buys a batch, but does not use them all immediately, another builder can be issued with the next available plaque (and thus sail number) and build a boat before the boat(s) with the preceeding sail numbers have been built. Where I have IYRU/ISAF/World Sailing plaque numbers for a year, I've put them in the comment field
- From 2001 to 2015 the data is mainly from Measurement certificates issued in the UK. As not every boat gets measured, and some are built overseas, it's possible the figures for a year might be slightly out, but it won't be by much.
- From 2016 onwards the data is from Winder Boats. As they are not the only Licenced Builder/Kit Manufacturer, it's possible the figures for a year might be slightly out, but again, it won't be by much.
|Year||From Boat||To Boat||Comment|
|1963||1||869||Mk 2 interior introduced (exact number of the change is unknown, but 810 is a Mk 1, 813 is, I think, a Mk 2 (?))|
|1964||870||3058||Boats built prior to 1965 are considered "Classic"|
|1966||4578||7489||Spinnakers were introduced|
|1986||68076||68250||Bell/Ferranti all GRP hulls introduced|
|1990||69021||69180||Mirrors become an International Class with rules administered by the IYRU (renamed ISAF, now World Sailing). Boat 69070 and onwards must carry blue and white IYRU/ISAF/World Sailing plaques.|
|1998||69916||69962||Bell Woodworking Ltd. ceased trading.|
|1999||69963||70031||Widebeam Ltd took over production of Mirror kits. End of sail number data from Bell/Widebeam|
|2001||70102||70130||Widebeam Ltd ceased trading. Trident-UK obtained licence to manufacture kits & boats.|
|2002||70131||70215||Trident-UK start building GRP (FRP) hull with Mk 2 interior|
|2006||70426||70465||Bermuda rig introduced|
|2016||70872||70899||World Sailing sold plaques 70882-70912|
|2017||70900||70927||World Sailing sold plaques 70913-70935|
|2018||70928||70958||World Sailing sold plaques 70936-70958|