Well, it depends a bit on what revolutionary era you mean (the American or the French?).

:-)

Luckily, the answer is fairly similar for both. So, ships of the period were built with several kinds of wood, generally hardwoods for the structural parts and hull, and softwoods for decks, masts and other fittings. Old oak was preferred for the structure of the hull (its internal ribs), and specific shapes of oak were used for the knees (the bent timbers used for bracing). Although you can steam wood to bend it for knees, it was preferred to identify oak trees with natural bends in them (often formed where a big limb leaves the trunk) and to use those for knees, rather than having to steam the wood and set it. Steamed wood never has as much strength as naturally-growing wood.

For masts and yards, fast-growing softwoods such as pine were highly prized. The pine forests of what is now the northeastern US, and southern Canada, were marked in colonial times with the king's broad arrow to designate trees for shipbuilding.

The primary source of old-growth oak timber during the period say 1750-1815 (to cover all our bases) was Britain's forests, which rapidly became denuded due to this demand. Colonial oak was a substitute, but its availability was lost after the American colonies broke away, so the British turned to other innovations, including:

• Building some small ships out of softwood. There were five so-called "fir frigates" built in 1757, which used fir as their hull material. They were very light and fast but also had very short service lives; the longest-lived was the Boreas, sold out of service in 1770. Trent, Shannon and Acateon were broken up in 1764, 65 and 66 respectively, and Hussar was taken by the French in 1762. There were later fir frigates that served roughly 1813-1829, also very short service lives.

• Using extra bracing for older ships, instead of replacing knees and compass timber. Gabriel Snodgrass used diagonal riders bolted into the hull, across existing timbers, to stiffen ships. Robert Seppings (Surveyor of the Navy 1813-1832) improved on this by using diagonal stiffeners to make ships longer without losing rigidity.

• Using iron plates bolted through chocks to replace knees. This was a stopgap measure but it led to shorter service lives as well, because iron corroded and it does not work (flex, move around) with the rest of the ship.

• Changing ship design -- wall-sided ships, those without a tumblehome, save considerably on compass (bent) timber, as well as giving more interior room and a wider setting for standing rigging.

• Building ships out of other materials altogether. Jamsetjee Bomanjee, of the Wadia family of shipbuilders, was master shipbuilder at Bombay 1792-1821, during which the shipyard built many ships for the British navy out of teak. (His HMS Trincomalee is still afloat today, as a museum ship.)

After the loss of colonial oak from the Americas, efforts to import it from Canada increased, and the Admiralty looked elsewhere. Naval stores (pine tar, spirits of pine, as well as pine itself) were also imported from Scandinavia.

There was a bit of a lull in British shipbuilding following the loss of the American colonies, and again when Earl St. Vincent became First Lord of the Admiralty in 1801 (despite the war, he scrapped a large number of dubious or obsolete ships and reformed the dockyards; in the long run this was a good idea but it pinched the Navy in ship replacements at a crisis point).

I hope this helps -- let me know if you have more questions!