If effective sailing (developments such as rigging allowing tacking, much higher speeds and larger ships, making ships similar to ones of the 1700-1800 era available) became available during the middle medieval period (1300-1400) how would it change warfare? What weapons would become common on board ships, given that cannon technology was not anywhere close to where it was during the age of exploration around two hundred years later? What tactics would become effective in naval battles?
I am nowhere near an expert in anything medieval, sailing, or warfare related, but I'll give this my best shot:
There was already some warfare tactics for navel battles that the Vikings used, mostly involving using speed of rowing for ramming other ships.
"While naval Viking battles are not as common as battles on land, they did occur. Viking ships would often try and ram ships in the open sea. They would propel the boats by rowing fast directly at defending ships that were vulnerable and isolated from their fleet. To combat this, defending fleets would raft up with the bows of their boats facing the attacking Vikings. Depending on the size of the defending fleet, The Viking ships allowed them to maneuver their boats by rowing around such ships to flank them. When they got close enough, Vikings would throw spears and use their longbows. Archers would be positioned in the back of the ships protected by a shield wall formation constructed in the front of the ship."
I would assume that some of those same tactics would persist (especially the use of bows and arrows for ranged combat when boats got close enough).
If we're talking about bigger ships, there could also be the potential for medieval siege machines to be adapted for use naval use.
Perhaps something like a magonel would have been of use, but that could have also caused issues with its sheer size on the ship.
I'd imagine that some of the tactics would also differ depending on why two ships are in battle - if we're talking pirates or groups that would be more likely to want to capture a ship rather than a battle to outright sink it, then something like a ballista may have been useful because one could then use the tactics of attaching ropes to arrows and reeling another ship in so that you could board it and do close combat. Ballistae also had the another advantage that I could see as useful when out at sea mentioned in the wiki:
"Ballistae could be easily modified to shoot both spherical and shaft projectiles, allowing their crews to adapt easily to prevailing battlefield situations in real time."
So, it sounds like ballistae could have been used a both an anchor and a less-powerful cannon against another ship.
The introduction of cannon into naval tactics was a gradual affair.
- As late as the 16th century, Spanish ships put a much greater emphasis on boarding and infantry combat than the English. The defeat of the Armada proved the English right, but before that boarding did work. The Spanish would try to fire one broadside and then go to cold steel because their ship's troops were better trained than the opposition.
- In the Mediterranean, galley warfare included boarding as well. The ships at Lepanto mounted a few cannon in the bow that were impractical to reload once the battle lines were close.
So the weapons would be swords, bows, crossbows, and short boarding pikes. Plus rocks and metal darts hurled from mast tops.