This raises a few questions in my mind: 1- Do shipping lanes still stick to prevailing winds, or are more direct routes significantly faster? 2- Would becalme

This raises a few questions in my mind: 1- Do shipping lanes still stick to prevailing winds, or are more direct routes significantly faster? 2- Would becalmed seas or being blown off course by a storm be a big enough risk that ships would still need a full compliment of fuel, or close enough as to make the maintenance costs of both engine and sails, weight and other factors override the benefit? 3- Does the addition of sails increase the risk of rolling or swaying stresses on the ship? I imagine this might require some extensive structural changes or upgrades to ships, with no idea of what the cost would be compared to a different kind of retrofit (i.e. continuing to use propellers but with a different fuel source).