Few will deny the merits of the knot as a unit of speed. It does in one syllable what all other units of speed take three or more to do. It is accepted and used by a great many countries, including those like France which show a general preference for the metric system. Aviation has taken to it as well as shipping. It is not therefore surprising that the full acceptance of the Système International d'Unités (or S.I.) is meeting with some opposition when it offers to supplant the knot.