propeller - 2 or 3 blade
Most boats go forwards most of the time. Even when they''re sailing. Having the drag of a three-bladed prop ALWAYS slowing you down, always making it take longer to get up to hull speed, always growing more barnacles, seems a heavy price to pay for the .000004% of the time that you go backwards. It may be worth it to you, but it might be worthwhile to weigh the pros and cons more carefully.
In another thread on this topic, Hamiam suggested knowing more about your boat - size and type - before making any suggestion. For example, if you put a 3-blade prop on the wrong kind of boat -- such as a J/30 - and then want to sell it, the prop makes it look like you didn''t know what you were doing. Any prospective buyer will then question anything else you did with the boat, and it will inevitably lower the price you get. So this $100 investment can cost you a couple of thou'' , if you''re not careful.
Perhaps a 3-bladed prop is the right one for you.
But you need more than a one-size-fits-all reason for it. Nothing in boats is that simple.