WHY DO ferries take so long to cross to the Continent at night, asked Arthur Nicholls of Norwich (Independent Traveller, 13 November). 'I should have thought the answer was obvious,' writes Roger Hand of Kintbury, Berkshire.

'People using overnight crossings want a good night's sleep and the companies want them to spend money in the duty-free shops, bars and restaurant before they go to their bunks. So it's not surprising that overnight crossings last eight or nine hours. Presumably, the slower the ships travel the less fuel per mile being used, and this benefits the operators too.

'Conversely, the day crossings tend to be tedious and the ferry companies presumably try to minimise the journey times to attract passengers. There must also be a limit to the demand for duty-free goods and food (and, to a lesser extent, for drinks). The quicker they satisfy that demand, the lower their staff costs.'