The Scottish Coastal Rowing Project

We have partly made our oars, out of clear and better Douglas fir, which planes up really nicely. But we are not clear about how kabes and humlibaunds work and so have not made the wear strips on the oars. As the drawings show them, the strips don't prevent the oar sliding in and out, but it seems to me this would be an advantage. I would also like a system which did not have a bit of slack so each stroke does not have to start with a clunk.

Looking on some websites with pictures of scandinavian rowing boats, it appears that in Norway they have wide wear strips with notches and I can see the notches keep the humlibaund and stop the oar sliding out. Another concern I have is making sure the humlibaund does not get ground between the oar and the routh on the gunwale, since it would not last long if it did.  

Ideally one would have a system which would locate the oar from sliding in or out but could be adjusted so as to "change gear" for different conditions or rowers. Also it should be easy to ship the oar and lift it clear of any obstacle.

Does anyone have any views? Any close-up photos of boats with oars deployed would be appreciated.  I found this forum rather hard work to get registered, but nowIi'm here.