Altitude adjustment
Ray,
Your motor DOES compensate for altitude - believe it. And what has already been stated, if you want to improve your performance at higher altitudes you need to change the prop pitch. Here is a link to a good article on this - Understanding Propeller Pitch - and a quote from the article: "If you're changing pitch on a recreational boat, remember that each inch of pitch is worth about 200 rpm. Lowering the pitch will increase rpm and vice versa. For example, going from a 23 pitch to a 21 pitch will increase engine rpm by about 400 revolutions."
As you go higher in elevation, you will notice a decrease in engine rpm's with your current prop. If you know what the decrease in engine rpm's actually is at 5000 feet elevation, you can determine the amount of pitch decrease you need. You may want to check with Yamaha directly and ask for some technical advice on this as they may have the data to correctly advise you on how much pitch decrease is required. Your dealer may also know if you have higher elevation lakes in your local area that they deal with on a regular basis. And remember, your motor has an upper rpm limit that you absolutely don't want to exceed, so be sure to choose a pitch that will increase the rpm's but not put you over the max for your motor.
Bob Hicks, from Utah - I’m 80 years young and going as hard as I can for as long as I can.
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