Hi Warren
There is a contract for her sister ship Aurora (28) 1776 which should be a big help as there are a lot of details. Two examples from the Aurora contract.
KEEL ………… The Keel to be Elm, not more than 4 pieces 13½ ins square in Mids, sided afore 12 ins, & at the aft part of the rabbet of the post 10 ins. The Scarphs 3 ft 8 ins long, tabled one into the other, laid with white Flannel oakum bolted with Six Bolts 1 in diameter. The lips of the said scarphs not to be left more than 3⅞ in thick.
FLOOR TIMBERS The Floor Timbers, between Timber 5 & Timber C in the Bearing of the Ship to be sided 12 ins, & from 5 to 19 aft & from C to M forward inclusive sided 11 ins, & from 19 aft, & M forward sided 10 ins, to be in length in Mids18 ft 6 ins, afore & abaft as the Draught directs.
CHOCKS No Chock to be larger on any Floor Timber than will admit of one foot whole Wood below the cutting down in &, out & afore & abaft to increase as the shape of the timber may require for strength, to be moulded at the heads 9⅛ ins, in & out & Afore & abaft 9¼ ins. Every other floor timber to be bolted thro' the main Keel & the bolts carefully clenched before the false Keel is put under with bolts of 1 ¼ ins diameter
You can also find scantlings for ships of that era in the Shipbuilder's Repository 1788 which is available along with the Establishment of 1719, 1745, and 1750 and David Steel's Elements and Practice of Naval Architecture in Scantlings of Royal Navy Ships from Seawatch books. NB: There are some differences at times between the contract and scantlings in the Repository but usually not significant to the naked eye at our most common scales. Where there is conflict it is best to use the contract figures as both the Shipbuilder's Repository and Elements and Practice of Naval Architecture are generic to specific ship sizes by number of guns over a spread of about 15 years in the latter 18th century into the first few years of the 19th century.
If you do not have a copy of the contract but would like one please feel free to PM me and I can email a PDF to you. I would post it here but it is 28 pages long.
Allan