Is the Jiffy Jax system strong enough to support the weight of a large sail with only line?
Absolutely. Since the sail is only supported laterally, line is more than adequate to support the sail. In fact, even the cheek blocks can support up to 1200 pounds each. However, it is a very bad idea to use the Jiffy Jax support lines as a topping lift! Do not allow the full boom and sail weight to be supported by the Jiffy Jax system!