Fleas as a navigational aid

We have to figure that the Vikings went off-course quite often either because of storms or fog. If it was impossible to see the sun during the day or the stars at night one had to resort to other options. Fleas followed people both at sea and on land. If you went off-course you could pluck a flea from your hair or another body part and put it on the tiller. Fleas always hop or crawl north so you would know the direction and could correct your course.