IMHO the red cards represent a tack that did not go so well. During the first hourglass, the captain uses his ship's dwindling momentum to keep pushing through the eye of the wind. If that is not enough, for the second hourglass, he has the crew boxhaul the rig and push the bow the rest of the way through the wind as the ship is blown backwards by the backing sails. It is similar to backing the jib and putting the helm over the other way on a modern sailboat, only a tad more complicated. As far as introducing a probability factor, it would have to be a fairly remote chance of failure. These captains were professionals responsible for an important part of their country's strategic well-being (Victory alone had a greater weight of shot than Napoleon's entire army at Waterloo). Would you risk that on something with a 1 in 6 failure rate?

I like the idea of not being able to fire while using red cards, but all in all, I think the rules are a good compromise between playability and reality.