I am in the Pit Hole too......I have completed all my puzzles except this one......now everything else are not important, even when all the food are washed away by the Tsunami, I am ok, as food builds up really fast now.

But, I don't have a master builder. Once I had an island event where the boat wreckage reappear, I was so happy that I got my specially trained villager (with experience in a few trades) to be train quickly as builder. But, after clearing the beach, he experience is only halfway, not enough to be master builder. Now he has long passed on and laying in the congested grave......The next time I will get the youngest villager to clear the beach so that he/she has the highest chance to live and see the second wash up of the debris......

Insist on waiting and see when I can complete the game......