ETFs: ETFdb Realtime Ratings. This page provides ETFdb Ratings for all JPY (Japanese Yen) ETFs that are listed on U.S. exchanges and tracked by ETF Database. The ETFdb Ratings are transparent, quant-based evaluations of ETFs relative to other products in the same ETFdb Category.
Once again if you are asking about a 2-stroke motor the following does not apply. If the motor was properly maintained you should expect the life expectancy of gas-power 4-stroke marine motor to be between 1000 and 1500 hours. Or, another way to think about it that every 100 hours is about 15,000 miles. Once again this is just a rule of thumb and many variables affect this range. If you are in the market for a used boat then I will also suggest you consider a marine surveyor: http://www.marinesurvey.org/ .
The best propeller size for your boat and engine combination is based on the recommended operating range at wide open throttle (w.o.t.) for your engine, which you will find in your operator's manual. This will be expressed in terms of a certain horsepower at a certain RPM (revolutions per minute).