Booking Manager always allowed you to add documents to the boats themselves, regardless whether they were images, pdf's, Word files etc. Those files were available to any portal or web service user as well.
With the latest 9.4 version of the Booking Manager it is possible to select whether you want make your documents public or not.
Open Work > Yachts, select a boat (1.) and click on Documents (2.) to see all the added documents on the boat.
Under Documents you will notice a column called Visibility (1.). The documents with comment Main, Interior and Plan image are images of the boat and were added through the Images tab and must always be available so they can not be made private. The documents you added through the Documents tab can be clicked on and be made either Private or Public (2.). Only documents that are made Public are available to the users on the Portal or Web service.