OJ C-Clamp Prop Puller
Why You Need ItInboard boats have what is called a tapered shaft, which means the diameter of the prop shaft the propeller sits on gets larger further away from the end. That taper is designed to allow the prop to "seat" on the shaft for better power transmission, as the prop is literally forced further up the shaft when driving the boat forward in the water.
That taper can make it extremely difficult to remove the prop when replacing or exchanging it with a new one. Many people think the prop will simply slide off once the cotter pin and nut have been removed, and are frustrated to find that is not the case, especially when their prop is damaged, and they have a replacement but can't get the ruined one off.
Not having a prop puller to go with your spare prop is akin to having no jack in your car; a spare tire doesn't do you any good if you can't get the old wheel/tire off to replace it.