Perhaps it is understood, but many, many boats sell without the assistance, and commission, of a broker. These sales are not recorded in SoldBoats/Yachtworld. SoldBoats is a data source. As has been said, when twenty 40’ Mainships sell in a 2-year period the data is pretty good. When four boats of a model sell in 2-years and only two are through Yachtworld, there is little value in the data.
Following the current public listings of a boat model you are interested in buying or selling, noting which ones sell, their price and relative value is another form of data. Many type-clubs, such as Krogen and Great Harbour, have public bulletin boards (classified’s) listing club members’ yachts for sale. Many of these are private listings that never appear in Yachtworld or SoldBoats.
In a private transaction, 100% of the buyer’s price motivates the seller to sell. Some buyers and sellers want or need the assistance of a broker. Many do not and for those that do not, the 10% commission overhead makes reaching a mutually satisfactory price agreement that much more difficult.