Have got our Men o' War rules working well for small ship actions I turned my mind to modifying them for large fleet actions. The issues to be addressed were 1) I only have 10 model ships & 2) the rules needed streamlining to allow actions of 20+ ships a side to be resolved in a good timeframe.
I fixed the ship problem by making counters by fixing printed graphic to 60x54mm plastic bases salvaged from Perry 28mm plastics boxes. Not as good looking as ships, but cost nothing & perfect for game development purposes. I also printed 4 A0 sheets of 65mm hexes and worked out how to paint them blue (an acrylic paint wash applied with a sponge roller).
The current rules actually work very fast as they are, but recording damage on separate damage logs doesn't work well with a lot of ships. With a large fleet you really need to be able to get all the info you need for combat by looking at the ship. The command logs for controlling movement work fine for any sized action and mostly orders are by squadron & follow the leader anyway.
The main change is to modify the ship stats so there are less dice per broadside and less hits need to knock ships out. With less hits to record, they can be recorded by using coloured counters on the ship counters. I also took out some subtleties like secret chain & double shot options which add a lot to a small game, but become tedious en masse.
Cape St Vincent 1797:
British: 15 ships of the line with elite crews. James in command.
Spanish: 25 ships of the line with raw crews. 15 in the weather group with Mark in command. 10 in the leeward group, Jim in command.
The battle didn't go exactly the same way as the historical, but the result was similar in the end. With a large part of the fleet downwind, the Spanish just couldn't use their superior numbers to counter the superior skill of the British.
The whole battle took 2 hours and a enjoyed by all. So now we have a one page addendum to the Man o' War rules allowing them to be used for large battles.