Re: difference between the two?
OMG -- they must be out to get me tonight. Semi-private joke sir. The props will likely have little effect on wakeboarding. It's the boat that makes the wake. Add some ballast to the rear to make more wake. The difference between the two props is about 400 engine RPM. The 15 will give you hole shot the 17 will give you a theoretical higher top speed. Why "theoretical"? Because the prop calculator you used does not know what type of boat you have, what your the current maximum rpm and speed is with your current prop, and what the average load is. You need to make some test runs with your current prop to establish a base line. You also need to work with engine mounting height to make sure you are getting the most out of the prop you have now before spending bucks on a new one. You may already have the optimum prop. If, at wide open throttle, the engine rpm is in the manufacturers maximum recommended WOT rpm, the prop you have is ok. If the engine overrevs the prop has too little pitch. If the engine is operating at less than the recommended RPM the engine is lugging and a decrease in pitch is required. Speed will be what the proper prop delivers. Once you have setup correct, then think about "tweaking things with the prop selection". Aluminum is fine for the average recreational boater. They are light weight, easily repaired, less expensive, and if you do strike a hard object (say a rock) the prop will break rather than the gear case internals. Stainless is pretty, generally more efficient, heavy, more expensive, and more likely to break very expensive gearcase internals if you strike something hard (like a rock).
