Pour the beer, rum, molasses, soy sauce and lime juice into a bowl. Stir in the garlic, ginger, chilli, thyme and marjoram. Season with allspice, cinnamon, nutmeg and bay leaves. Place the pork chops into a zip top bag and pour in the marinade. Refrigerate overnight.
Prepare the barbecue for medium heat. Take the pork chops out of the marinade, place on a plate and allow to sit at room temperature for 15 to 20 minutes as the grill heats.
Season the chops to taste with salt and black pepper. Barbecue the chops on both sides until cooked to required doneness. Let the pork chops rest for about 5 minutes before serving to allow the juices to redistribute.