It is funny to see that some of the members had the same idea I had playing SH: "Wouldn't it be great to have a game like this set in the Age of Sail."
Personally, I really liked the crew management system in SH3 (it was a shame they didn't include this in SH5). I remember one time sailing for a very long time and suddenly my engine shut down. It wasn't for lack of fuel (I'll admit I was cheating) but my crew was simply too tired. I had to reassign them all for even the officers were tired. This also meant that if I were to come under attack I wouldn't be as efficient at repairs as I could be.
If this system could be implemented, even in a more basic form, it would really add to the depth of the game. Under attack - assign more to the guns, sprung a leak - assign more to repair at the cost of gun efficiency etc.