Consider using the Harken 349 29mm Stand-up Block series that includes Low-friction Carbo Air blocks. These blocks, with a 29mm sheave diameter, can handle maximum line diameters of 8mm and working loads up to 150kg, or 330lbs. They are designed to be lightweight, strong, and affordable, making them a reliable and efficient choice for sailboat trimming. Add them to your collection of Big Boat blocks for a seamless, effortless experience.