10 days would be doable but you'd need an experienced team happy to spend that long at sea and keep the boat going - 15 days probably more realistic. Biscay as you say can be tough so you'd need a weather window. Ideally you want to go far enough offshore to go round the outside of the shelf.
10 days would be doable but you'd need an experienced team happy to spend that long at sea and keep the boat going - 15 days probably more realistic. Biscay as you say can be tough so you'd need a weather window. Ideally you want to go far enough offshore to go round the outside of the shelf.