So with the Mediterranean theme this week, and my personal delving into the topic of Napoleonic France, I came to ponder the topic of navy composition. Powers such as France have two main naval fronts, the Atlantic/North sea and the Mediterranean. Did the ships France employed in its ocean fleets differ in any way from the Mediterranean fleets? If there was differences, what were they and why? What differing challenges and tactics would an admiral face in these fronts?
This is a great question, although the answer is that basically by the time of the Napoleonic wars ship construction didn't differ that much between fleets -- ships would be expected to operate in multiple theaters of war. But we can use the question to talk about differences between British and French shipbuilding, as well as some types of ships that would be used in the Mediterranean and not the Atlantic.
The first thing we might want to do is to explains some differences between the Med and the Atlantic. The Mediterranean is, of course, a much smaller sea and has major choke points at predictable spots, allowing fleets to keep watch on shipping more easily than in the Atlantic. The Med has essentially no tidal action; tide variations are reckoned in centimeters, while the Atlantic ports of France, Spain and other countries have tidal variations of meters or several meters. And the Mediterranean is generally calmer than the Atlantic; although I don't want to underestimate the force of storms in the Med, they simply don't compare to the fury of storms in the North Atlantic and the conditions ships would need to face there.
So let's talk about types of ships first, then shipbuilding. In the Mediterranean, even through the period of the Napoleonic wars, we do see galleys making up a small portion of a fleet, though not in large numbers and generally in the Italian states. The largest force of galleys belonged to Venice, but their close cousins, oared gunboats, were fairly ubiquitous and used to protect ports and choke-points at sea. The galley and the gunboat can both use sails, of course, but the fact that they use oars as their primary means of propulsion means they can be used to harass sailing ships and run away independent of the wind. Both also mounted cannons at their bow and stern (some small gunboats only had a bow cannon) rather than on the broadside.
The Med was also unique compared to the Atlantic in having a large number of xebecs, used especially by corsairs but also adopted by some navies. The xebec would usually have oars but also carry lateen sails, while some types of xebecs (polacre-xebecs) would carry a square rig on the foremast and lateens elsewhere. Some navies used large xebec-frigates, which could switch rigs between square sails and lateens -- the fictional battle in Patrick O'Brian's Master and Commander was based on a real action between HMS Speedy and the Spanish xebec-frigate El Gamo. (The crew of the Speedy, with 14 guns and 54 men, boarded and captured the 32-gun El Gamo, which carried a crew of about 320 men, after a short action.)
But in any case, you were asking about ship construction. I'm going to quote at some length from an older answer which gets to some of the differences among British and French shipbuilding philosophy.
At this point, then, it's worth pausing and considering what was happening in the world of ship design in Europe. The large French ships, at least nominally, were being built to a plan dictated from Versailles, although individual yards could and did make modifications particularly to hull shapes that could change a ship's seaworthiness. But the French designs were being dictated from academic studies (the French were the first to conceptualize of a metacenter of a ship, and to theorize about metacentric height) and they were not built well. French ships were lightly built, fastened with nails instead of treenails, and their designers favored very long hulls and taunt (very high) masts, meaning their ships would be very fast off the wind. But their performance suffered greatly close-hauled (that is, beating into the wind) and in any kind of a sea state. They were designed with light timbers to be buoyant, and carry guns high, but light timbers suffered greatly under normal hogging and sagging strains. Their theories also led them to believe that the working of a ship helped it to move faster, rather than simply causing great strain on a ship's inward parts; all these things meant that French ships had high building costs and maintenance costs and short lives, and dockyard constructors knew they were building poor ships. (I should mention, in fairness to the French, that they had natural interests in the Mediterranean that the British did not until after the capture of Gibraltar; their ships performed excellently in that odd tideless sea.)
In contrast to this, British designs were by midcentury and later being voted on in the broad sense, but it was up to individual yards and shipwrights to build to specifications. British ships tended to be shorter than comparable French designs, but they were more heavily timbered; their weight helped them perform well going to windward and in heavy weather; and they had full hull forms that could be stored for long voyages, either spending time on blockade or long periods of time overseas. They were meant to be inexpensive to build and maintain, in a navy that knew that they would have a difficult time keeping pace simply out of their own building in matching their needs.
In any case, in practical terms, the French designs didn't actually tend to be faster than the British; given the technical constraints at the time, speed can't be accounted before merely by construction. The main limiting factors seem to be the cleanliness of ships' bottoms (which docking and coppering, both British advantages, contribute to) and the ship's trim, rig and the skillfulness of the crew. British ships often outsailed French ships in conditions that should have favored the French. (To briefly break the 20-year-rule, skill at sailing even today[1] makes the difference in races between boats built to be identical.) Moreover, ships captured by the British tended to be faster after re-rigging, re-stowing of holds and re-hanging of decks, suggesting that there was technical knowledge in the shipyards' hands that was not there for the French.
I would be remiss here also not to mention the American navy, which largely adopted British shipbuilding practices (because in practice their yards and their methods had been British for a century or so before the Brits lost the colonies). The nascent American navy, famously, built six frigates to be (oversimplifying here) the equivalent of battlecruisers, heavier than any British frigate but able to run away from any British ship of the line. There were supposed to be two classes of frigate, three in each class, but idiosyncrasies among the shipyards meant that they had wildly different performance.
I've written other answers before about ship design and shipbuilding, here are a few:
https://www.reddit.com/r/AskHistorians/comments/3pn7v5/what_changes_occurred_in_the_construction/
https://www.reddit.com/r/AskHistorians/comments/2709jm/how_would_a_britishhms_frigate_built_in_1715/
