The planks I got are 800mm which will not be able to fully span the longest stretches of the hull with curvature included.
Normally you can not find long wood that span the whole ship. Woods are joined end to end in shipbuilding. You should sand the end of the planks like below picture and try to glue on bulkheads as possible as you can. Sanding the ends and gluing them in this way makes it easier both gluing and sanding.
I always do like that. And here is the result