A heavy fog in the Western Isles is threatening to thwart a plan to gather all the Islanders votes by plane.
Eilean Sar was meant to be one of the first to declare after it was decided to bring a plane in to gather votes but it won't be able to fly unless the fog clears.
A decision will be taken when the polls close on whether to use a boat instead and that could delay the final declaration by several hours meaning a referendum result wouldn't be known until around 7 or 8am tomorrow morning.
Of course, depending on the way declarations have gone elsewhere we could already have a winner by then.
By Debi Edward: Scotland Correspondent
It is perhaps in light of the momentum that the Yes campaign has gained that the No campaign went on the attack today.
They distributed a document - leaked by an NHS doctor - which states:
The Better Together campaign claims that flies in the face of their rival's claims that only a Yes vote can protect the NHS from cuts.
Well, the Scottish government have said they are the ones protecting and increasing the NHS budget in Scotland, and that only independence can offer the health service a brighter future.
The Yes campaign really have been able to gain some traction on this NHS debate despite health being a devolved issue - the Better Together campaign say it's "the biggest lie" of the referendum so far.
Is the pledge to give Scotland more powers a last throw of the dice, or the reassurance some voters need to seal a No vote?Read the full story ›
Bounce for leaving the union following second debate this week, but only 43% expected to vote yes in referendum on September 18Read the full story ›