about the boats on Amon Hen

[lathspell]

If this has come up before, please tell me where the thread is, and this topic can be closed.

I'm reading the LotR (again) and noticed something when the Fellowship is on Amon Hen. I'll set a quoet from FOTR - Book 2 - The Breaking of the Fellowship:

'Of course it is,' answered Sam. 'But not alone. I'm coming too or neither of us is going. I'll knock holes in the boats first.'
Frodo actually laughed. A sudden warmth and gladness touched his heart. 'Leave one!' he said. 'We'll need it. But you can't come like this without your gear or food or anything.'

So Sam has the idea of knocking holes into the boats, and Frodo says him to leave one for themselves. Afterwards there is no information if Sam actually does knock holes into them or not.
Later Boromir is laid in another boat and floats down Anduin. He did not sink for Faramir saw him float in the Anduin near Ithilien and that is many miles away from Amon Hen.
The other boat Aragorn, Legolas and Gimli hided in some bushes. But Gimli says: 'Our choice then is either to take the remaining boat and follow Frodo, or else to follow the Orcs on foot. There is little hope either way. We have already lost precious hours.'

So it seems that none of the boats have holes in them for both of them could be used. Still I find it quite unlikely for Sam to forget such a thing. So, now my question is: Did Sam forget to knock holes in the boats (which seems quite unlikely to me), or did Tolkien make a mistake in his book considering the boats (which also seems quite unlikely for he read, wrote and bettered it for a long time)!

I'd like to hear some of your opinions on this.

greetings,
lathspell