The words skipper and steersman or helmsman were not used in the same way in Viking times as they are today. The skipper on the Sea Stallion is the ships captain or commanding officer, and the helmsman is the skippers subordinate and deputy. But in Viking times it may have been the other way round. The steersman in Viking times was the ships owner and had military command, whereas the skipari (skipper) was the next-in-command or an ordinary member of the crew.
But not much has changed since Viking times when it comes to the skippers role on board. The skipper and helmsmen just like 1000 years ago have overall responsibility for the ship, crew and equipment and for making sure the ship reaches its destination.