What are the evidence for no god?

[I_am_not_mafia]

If the account of Noah's flood isn't true, then how is it possible that we have found Noah's Ark split up into three pieces?

You've been misinformed.  No one has found Noah's ark, in pieces or in any other condition.

There's also evidence that Noah's ark could never have existed because we know the largest possible size of a boat made out of wood and if you try building anything larger then it will flex too much and sink. Trying getting two of each animal or bird onto that boat including all the food for them to survive.

https://en.wikipedia.org/wiki/Wyoming_%28schooner%29

Because of her extreme length and wood construction, Wyoming tended to flex in heavy seas, which would cause the long planks to twist and buckle, thereby allowing sea water to intrude into the hold (see hogging and sagging). Wyoming had to use pumps to keep her hold relatively free of water. In March 1924, she foundered in heavy seas and sank with the loss of all hands.

Genetics also shows us that the Noah's story is also false because only having two of each creature left would mean that there was not enough genetic diversity left.