The pirates should probably eventually make it out to Tripoli as well, right?
Also, I don't know about giving them caravels, that wouldn't look very historical IMO.
The Mediterranean needs to see more fighting with galley-type ships. Right now most early sea combat starts to take place after galleys and triremes have become outdated, and is ted by cogs. Cogs were used for a period in the Northern seas, in areas like England, Scandinavia and Northern Germany and France. We all know that the massive Genoese Cog fleet that develops at around 1400 is rather inaccurate.
We should break up the galleys and triremes into more units. My suggestion:
Light Galley - 1 strength, 5 movement. Barbary Pirates replace it with the "Fusta", +1 movement. (Mediterranean civs only)
Galley - 2 strength, 4 movement. 2 cargo Space.
War Galley - 3 strength, 4 movement. Norse replace it with longship, +1 movement, +2 Cargo Space. English, Dutch, Germans, Polish, Russians, Swedish get "Cog", -1 strength, +2 Cargo Space
Galleass - Made available to all civs, 6 strength, 3 movement (significantly high production cost) Venetians get "Venetian Galleass", +1 movement, strength 1 promotion. Barbary Pirates and Cordoba get "Xebec", +2 movement. English, Dutch, Germans, Polish, Russians, Swedish get "Heavy Cog", -2 strength, +1 movement +2 cargo space, Norse get Longship again.
(Trireme eliminated, they stopped being used some time after the Peloponesian War)
Carrack - 6 strength, 7 movement, 3 cargo space, +50% movement cost on coast
Caravel - 3 strength, 9 movement, 2 cargo space, +50% movement cost on coast
Privateer - 6 strength, 8 movement, +100% movement cost on coast, privateer ability
Galleon - 8 strength, 7 movement, 4 cargo space, +100% movement cost on coast. Dutch get "Fluyt", -1 strength, +1 movement
Frigate - 8 strength, 8 movement, +100% movement cost on coast
Ship of the Line - 10 strength, 7 movement, +100% movement cost on coast
Eliminate War Galleon?
Light Galley allowed from the beginning,
Galley enabled by Classical Knowledge
War Galley/Cog enabled by Lateen Sails
Galleass/Heavy Cog enabled by new tech, "Naval Artillery", tech will also give all pre-Galleas units +1 strength
Optics will not enable caravel
Carrack and Caravel enabled by new tech, "Advanced Sailing", will have all the same benefits as shipbuilding, tech will also give +1 trade routes to coastal cities and reveal Atlantic Access
Astronomy will be replaced by shipbuilding, providing all the same benefits of Astronomy except for AA. Will lead to trading company and not scientific method.
Astronomy will allow observatories, give great scholar to first to discover, lead to scientific method
Ship of the line will be allowed by Military tactics
The production and maintenance costs for navies will both have to be reduced in general, to provide for bigger navies.
With these changes, galleys will remain very formidable units at least in the Mediterranean, and will probably continue to be produced well into the 1600's. They should start to become obsolete with the introduction of the carrack, but still be large in number.