Winning strategy

Captain 1 wants to send the same message (attack at 22:00). However, this time, there are two new rules he must obey:

• He must spend 10 minutes preparing any new message for it to be valid
• He must include the history of every previous message in every new message

So, let's see what happens this time. As before, Captain 1 sends the message (22:00 attack) with the sailor on the boat. This time, however, it is different for Captain 2, because he knows two things for certain:

• The message must have taken 10 minutes to prepare
• There are no previous messages, so it must be the truth (even if Captain 1 is a traitor and put in the wrong time, it doesn't matter; if the majority of captains followed this suggestion and went with a 22:00 attack time, they would still outnumber those in the pirate ship and win the battle)

So, now it is time for Captain 2 to send a message. As required, he spends 10 minutes preparing the new message and he embeds Captain 1's message into his own. The sailor then sets off with this message (now in fact, it is two messages chained together as the second has the first embedded within it). Now it gets to Captain 3.

Remember, he's the traitor. So, what does he do? Last time, he changed the message to 21:00 attack so that captains 4, 5, and 6 would attack early and get overpowered. Now, however, he can't because, under the new rules, he has only 10 minutes to prepare a message for Captain 4. He has two options:

1. Cheat by changing the message to 21:00 attack. To do this, he needs to (a) spend 10 minutes creating his message and then (b) spend an extra 2 x 10 minutes working to create replacement 21:00 attack messages from Captains 1 and 2 to embed these into his message and carry out this 30 minutes of work within the next 10 minutes to avoid the other captains knowing that he's a traitor.
2. Admit defeat and prepare the 22:00 attack message during those 10 minutes.

In other words, every captain has got no more than 10 minutes to provide the next captain with something that would take more than 10 minutes to fake if they were trying to be dishonest. If they can't deliver it within 10 minutes, everyone knows they're dishonest and ignores them, rendering their attempts to mislead others useless.