Yard Numbers, Sail Numbers, and Hull Numbers
The Yard Number is the number on the plate in the hatchway. It consists of a letter then some numbers i.e. A 123. There is a school of thought that the prefix letter originally indicated from which shed in Waterlooville the hull was made, but this can't be substantiated. What is known is that the system represents the specific model being built. The digits represent the number of that specific hull. The yard number is also found on cabin fixtures and fittings, written in pencil or wax crayon on the underside of removable wood panels such as locker lids. It has also been found on various parts such as skin fittings.
The Sail Number is sometimes, but not always, a different number to the hull number. Some boats were registered internationally so weren't given class numbers (GK24s for example). Sail numbers were issued numerically and in series when orders were placed, but if orders were cancelled the next ordered Sail Number was issued to the next hull coming off the production line. As the hulls were coming off the production line in numerical order, the Sail Number issued to it was the next ordered and paid for Sail Number. In this way, Sail Numbers and Yard Numbers got jumbled up. A further complication to be added into the mix is that some designs used the same hull but different deck mouldings. And indeed, Westerly just didn't issue some numbers - 666 being a good example.
The Hull Numbers were stamped into the moulding of the hull on the stern of the boat on either the port or starboard side near the top of the hull. It is linked to the Certificate of Hull Construction number issued by Lloyds Register of Shipping and is in the form ABC 123456. The vast majority were issued by the Southamton office, so start with SOU, and invariably the last 2 digits indicate the year the hull was laid up. There is an example of a 1967 Centaur Hull Number here: . Early Centaurs (prior to 1973?....any advances on '73) do not appear to have this.
If by chance your boat's Yard Number and Sail Number coincide, that is a rare occurrence on most Westerly's. Some did match - Corsairs for example, will match. More often than not the numbers do not coincide and because a Yard Number is 219 it does not mean that the Sail Number is 219. For example the Renown shares the same hull with the Pentland, and the very first Renown built R1 has a Yard Number of O (oscar) 036. The original author of this information owned a Renown that had a sail number of R129 but a Yard Number of O (oscar) 243.