-Less right-clicking. I didn't like how you had to right-click all of the time to assign gunners or to man a rig. I think this kind of thing should be automatic. For example, if you place a unit on a cannon and it starts its turn there, the effect is present for the rest of the round. This brings up issues of realism (no one is on your cannons, so how can you still shoot?), but I think speed of gameplay far, far, far outweighs that issue.
-Zooming in for combat. This one borrows from TL's Imperium scenario. Ship-sized units (ships and sea monsters) would be able to fight each other on the main screen, but if a fight is initiated between a ship-sized unit and a smaller unit, the smaller unit would be sucked into a zoomed-in map of the ship. That smaller unit would then fight whatever is in the ship. Then, you can have ship-sized units grapple each other, connecting the maps of the two. Or, if it's a kraken versus a ship, if the kraken tries to grapple the ship (first thing to do if it doesn't want the ship to sail away), the ship and the kraken still fight each other in the main screen, but the kraken sends tentacles to the zoomed-in screen to harass the sailors.
More than TL's Imperium mode, this dream comes from countless hours of playing Ultima 3: Exodus. Every battle in that game was a zoomed-in battle. It just so happens that ships were involved, and any side starting on a ship would see that ship in battle. But, rather than having only one section of the map in combat at a time, all sections could fight at once. Cannons will be flying at the same time swashbucklers are dueling it out.
This is where my biggest problems are going to be. What happens when a third ship wants to grapple with a ship already in combat. What about a fourth? How much space do I have to leave in the zoom-in area for each ship?
-Putting the setting in the world of Wesnoth. I understand why Wesnoth add-on developers want to avoid the restrictions of creating stories in a world they don't have full authority over, but a naval scenario is a great opportunity to explore regions in Wesnoth's geography are defined yet haven't been full explored. The Great Ocean, to the west of Wesnoth, will be the setting of Full Sail. The waters are open and just about all of the kingdoms in the game will be able to participate.
-More emphasis on supply and demand. Of course, as a M.U.L.E. fanatic, I will be adding my own flair for economics into the game.
-More emphasis on diplomacy. Trade embargoes, privateers, etc. This goes along with the emphasis on supply and demand.
-More Cattan-like objectives. Rather than having a potentially infinite score, players will scores like: Largest Fleet, Most Wealth, Most Ship Sinks, etc.
-Option for an adventure mode. Want to play by yourself or co-op with a friend? It doesn't always have to be competitive.
Anyway, back to work.
