Deconstructing items

After some time swimming around I was not able to deconstruct Karve. I was using a hammer and had a workbench right next to it. I also noticed this once with one timber wall in the base when. I could not simply destroy the wall with a hammer, was for one piece only all others worked. For the boat, I destroyed it with mace manually. but the wall stayed there until I logged in/created server next time. Note I create a server (not dedicated), and play with my friends.