A daily Caledonian MacBrayne ferry (MV Isle of Lewis) sails from Stornoway to Ullapool on the Scottish mainland, taking 2 hours 40 minutes connecting Lewis with the mainland. There are an average of two return crossings a day, with an increase in frequency during summer months and a reduction during winter months. daily Caledonian MacBrayne ferry (MV Isle of Lewis) sails from Stornoway to Ullapool on the Scottish mainland, taking 2 hours 40 minutes connecting Lewis with the mainland. There are an average of two return crossings a day, with an increase in frequency during summer months and a reduction during winter months.