Demasted yachts and motor boats with max air draft of 5.4m may pass under the Pont Chaban Delmas when the bridge is down. There is a delightful 155m visitor's pontoon, the Ponton d'Honneur on the west bank just downstream of the Pont de Pierre. It has water & electricity, is securely gated, very inexpensive, and in the centre of town. The pontoon is run by the Mairie, not by the Port, so info is on the Metropole website, not the port's one: https://www.bordeaux-metropole.fr/Sortir-decouvrir/Le-fleuve/Bordeaux-Metropole-votre-escale-de-plaisance
We visited Bordeaux in our Nelson 38AC Andromeda in 2016 and had a delightful several days on this pontoon, only moving on because of a forecast 40°C! Bordeaux is well worth the long boring slog up and down the brown Gironde. It is possible for masted yachts to go through the raised bridge which is lifted for large cruise ships and maintenance. Details of bridge lifting dates may be found on https://sedeplacer.bordeaux-metropole.fr/Toutes-les-infos-circulation/Pont-Chaban-Delmas-Fermetures. Be aware that a masted yacht might be stuck there for several days!