Cheers for those Peter, they match up pretty well with what I'd imagined from your written descriptions.

I think there has to be a high probability that proto-vikings did use craft such as those you describe.
The thing that nags at the back of my mind is those projecting spurs. They look like rams, which is mainly why Phonecian biremes are brought to mind.

What are the spurs, and how would the skin be attached from the spur to the prow/upper rim?