Hei Runar - good idea with your "patent ties", it would seem to be great as you can slightly force it in or out to accommodate a swamped barrel. Probably easier with that wide plank that you have. Do you drill the screw holes so as to not crack the wood?
You've made a good start! Be sure to thank Martin, maybe give him a cup of coffee as a reward.
Hmmmm. Me learning Norwegian while in my 70's!