These oar sails would act like the wings on a modern hang glider. Either sailing down the face of a swell or down the slope of a mountain pass the oar sails allow the Viking sailing ship to become airborne at about 45 knots. It would be a ride worthy of the name Vikings.
Unfortunately, the sail and ropes from Oseberg and Gokstad were not conserved. They did not have the technology for this 100 years ago. We will have to wait (hope) for a new excavation.
It is important to note that the oars are not set to
act like hydrofoils. I tried that design on my test
boat and didn't like the results. The oars are braced
in such a way that they do not even touch the water
untill the ship is moving at about 5 knotes. That way
the pressure of the water makes the oars skim along
the top of the water about like a water ski. Actually
a trick water ski would be a better example. It is a
little wider and has a lot less drag because it is