Very neat build and tidy presentation 

A few thoughts from a non-sailor, absolutely no criticism intended since wouldn't have been able to do it any better myself. 
1. The nicely rolled up lines suggest that the weapon is "resting".
2. There is no crew present to be able to intervene if the carriage should start swivelling sideways.
3. The lines are used to swivel the weapon sideways and when in active use I presume that there is a least one member of the gun crew on each side keeping the lines stretched to keep the gun aimed and re-aim it when the direction to the target changes.
Question: Should those lines be belayed somewhere somehow ?
/ Robin 
 
 One possible solution, wrap the loose ends around the lines between the blocks/sheaves