I have often been asked how boat scantlings are determined. for the most part such questions fall into one of the following general categories: how is structure. Australia’s no.1 place to buy, sell or research a boat, and read all the latest news and reviews.. Boat trolleys. bryanston are selling ten "under the bottom rack" trolleys. six are 32" by 19" (81.5 by 48 cms) with 4 good 360 wheels. four are 26" by 14" (66cm by.