I have absolutely no experience with the Bahia, but checked out the rigging manual and parts list for the fun of it. What struck me was the recommendation of max 70 kg of static shroud tension. That is very loose, so much so that the jib luff wire/halyard tension would be off the lower end of the scale of most tension meters. This in turn means that any problem with the jib halyard turning block has nothing to do with its diameter, but rather being broken one way or another. Boats with 3 or 4 times that tension have 25 to 30 mm sheaves up there, and they don't kill the wire.