How often is the event held? [originaltext] Good evening, ladies and gentleme

Good evening, ladies and gentlemen, and welcome to the biennial Shipbuilding Research Convention.(86)I’m very pleased and proud, as the convener of this convention, to introduce to you one of the world’s leading research scientists in the field of shipbuilding, Professor Nathan Davidson.(87)Professor Davidson’s speech, entitled "Shipbuilding: the next twenty years", will form the basis of a book to be published later this year.(88)I’m sure that you’re all aware that whatever Professor Davidson has to say is not only fascinating and original, but also extremely pertinent. So, please welcome Professor Davidson.