I traveled from Scrabster to Stromness on the St Clair once when the St Ola was away for annual refit, although a bit rough the crossing only took 1 hour 30 minutes as I was coming off the ship I said to one of the crew it was the quickest I had done the crossing and he said the captain was F*****g mad and trying for a record on the crossing!
My later crossings for work were on Pentland Ferries who were less than half the price of Northlink for my works van and they were providing a service with no subsidy like Northlink! An interesting book to read is Pentland Hero which is about Pentland Ferries.
snorbens when I used the ferries with my car I disabled the alarm which was the best thing to do and you could still lock it.