These are called "tambour" doors, and there's a lot of info on here about fixing them, but you need that magic word tambour for the search. Are they completely missing? Or do they just not work properly?
Il Carriaggio — 1975 Argosy 24 | Il Progetto — 1976 Argosy 28 Center Bath | WBCCI# 15566
He has all of the virtues I dislike and none of the vices I admire. — Sir Winston Churchill