Hi John, Just curious as I do not have Mastini's book.   For what size ship, era and nation doeshe show a double set of training tackle?    The number of train tackles and use of single or double blocks depends on era, nationality and the size of the gun.  Regarding the type of blocks, the same goes for the running out tackle.   Many modern models of British ships for example show a single and double block when this was not the case for guns lighter than 32 pounders.   Allan