Let us suppose that at the beginning of the Napoleonic Wars, we have a 5th-rate ship similar in appearance to the 38-gun HMS Lively with a displacement of approximately 820 tons, and a top speed under sail of 13 knots. This class of ship is designed and expected to operate independently.
However, this ship has been built with 2020's equipment to be a type of Q-ship, with the following features:
The wooden outer hull is a substantial timber and copper veneer applied over and fixed to a steel hull capable of resisting the naval weaponry of the Napoleonic Wars era.
The masts and spars are made from modern steel alloys with a timber veneer.
The sails and cordage have been made from modern materials coloured and treated to look like period materials.
It has two 18,000 kW engines below its gun deck, attached to reversible variable pitch propellers, capable of propelling the ship at up to 20 knots without sails, or 25 knots under full sail.
It has an armament visually similar to that of the period ship, except that the rifled guns are made from modern steel alloys, have a precise bore, and can fire modern ogival high-explosive shells, with attached pre-made cordite propellant, and the guns have a 'flintlock' mechanism that conceals a percussion cap system. The guns' rifling is polyhedral, and has no lands/grooves.
There is a small supply of functional period ammunition and powder for the sake of appearance.
It carries both openly displayed period small arms, and concealed modern military small arms.
It has modern powered bilge pumps.
It has a modern desalination system.
The interior and exterior of the ship is designed to withstand a cursory examination by naval personnel of the era without appearing particularly unusual, however a detailed internal examination is likely to reveal the hidden modern features.
Resupply of modern consumables is not an issue.
How effective might a ship such as this be in combat against genuine Napoleonic Wars era ships? Against what odds would it be capable of prevailing? At what point might period naval personnel notice that this ship is significantly more capable than expected?