What a Drag! How to Add Pep to Your Boat for High Altitude Performance
The lakes may be hard to reach, but the views are breathtaking, the waters clean, and there's plenty of fish to be found. "Ain't no mountain high enough" ... wait a minute, let me get out of the clouds and come down. So... you wanna take your boat on lakes thousands of feet above sea-level? Well, I'm here to help.
What Is Classified as High Altitude?For a majority of people reading this, you may not care about this topic. But for the small percentage of people who live at High Altitude (HA) or you are going to move to a place with high altitude, this article is for you!
What Is Considered High Altitude?For humans, at 8,000 feet above sea level or higher, you'll experience altitude sickness. However, for motors, it can be as little as 1,000 feet above sea-level.
Examples of Different High Altitude LakesUsing my home state of Utah, there are a plethora of high altitude lakes. In the Salt Lake Basin, you have Utah Lake and Willard Bay. And there's the Great Salt Lake, but we don't really boat in that one—too salty! These lakes sit at around 4,000 feet above sea level. Then you can start moving up to lakes like Bear Lake and Flaming Gorge—both over 6,000 feet in elevation, which is quite a difference compared to sea-level. Another personal favorite high-altitude lake is Idaho's Island Park Reservoir, among many others:
- Yellow Stone Lake - Wyoming - 7,732 ft above sea level
- Lake Tahoe - California/Nevada - 6,225 ft above sea level
- Flathead Lake - Montana - 8,587 ft above sea level
- Dillon Reservoir - Colorado - 9,017 ft above sea level
Explanation of Horsepower Loss at ElevationBefore we go too far, I'll explain the math behind horsepower loss at High Altitude. It's basically like this: If you or a friend lives somewhere like California or a similar place you're used to the sea-level elevation. When you suddenly go up to a mountainous region like Utah, Colorado, Wyoming, you feel winded, lack energy and can even experience altitude sickness. I personally have experienced this. Traveling to South America, my flight took me to La Paz, Bolivia, which sits at 12,000-feet above sea-level! An absurd elevation which actually made me sick, suffering from lack of oxygen. This is the key. The higher you go, the less oxygen there is. And if you lack oxygen, a lot of functions start to go haywire. So if the human body requires oxygen, then what about your boat's internal combustion engine? It too requires oxygen to ignite fuel to generate power. Simply put—when you have less oxygen, you have less power.
Some Simple Math to ExplainRemember I said that I wanted to use math? Don't worry it's simple math, nothing too complex. I actually have Yamaha motor corporation to thank for the math. They did the hard work already to calculate this. To put it simply for every 1,000 feet in elevation you go up, you will lose 3% of your horsepower. For example: 4,000 feet = a 12% loss of horsepower 6,000 feet = a 18% loss of horsepower Ok now plug in some horsepower numbers: 150 hp outboard at 4,000 feet will lose 12% of its horsepower.
150 x 12% = 18. / 150 - 18 = 132 hpThat 150 has now suddenly become a 132 hp instead at 4,000 feet. What about 6,000 feet?
150 x 18% = 27 / 150 - 27 = 123Can you see where this is going? The higher you go the horsepower loss is more significant. For example, I have one customer who lives in Colorado. The closest lake to his home sits at 9,000 feet. 9,000 feet! An astronomical height resulting in a 27% horsepower loss! A 150 hp outboard at 9,000 feet is suddenly a 110 hp motor. That's a huge loss and there's no easy solution to it. The end lesson here? Don't buy under powered boats if you live in high elevations. A 19-foot boat with a 115 hp or even a 90 hp outboard still works well. But the same boat at 4,000 to 6,000 feet? It's essentially a big floating turd as it won't go anywhere. I don't mean to be blunt, but I have seen and dealt with it on countless occasions with my customers.
What Is High Altitude Boat Performance?High Altitude boat performance is when you get the maximum performance from your boat when you boat at the best lakes around. Joking aside I'm sure there are great lakes at lower elevations, but some of the lakes up here are just plain gorgeous!
Are You Getting All Your Boat's Performance?This is a tough question to answer, but the first place you have to look is the prop. The second question, which isn't as easy to fix, is does your motor have electronic fuel injection/direct injection? If it does, it'll certainly help a lot. If not—you'll have to mess with jetting, which I'll touch on later. The third question is does your motor have enough ponies under the cowling? Remember the math section? If you fish at H.A., having a bigger, badder motor on the boat will negate the percentage losses. For example, a 150 hp at 4,000 feet is actually like a 132 hp. If the same boat had a 115 instead then at 4,000 feet, it's actually a 101 hp. That 150 still has a full 31 hp more which will only help. You can always slow down, but it's tough to accelerate when the power isn't there. The last solution is to have a motor with a turbo/supercharger. I'll touch on this topic more down below.
How Do You Know You're Getting Optimal Performance?This is critical to know for many reasons. If you're not getting optimal performance, then it not only isn't fun, but can cost more money in fuel and unnecessary wear and tear. The number one rule of thumb when it comes to optimal performance is what is your WOT RPM? (Short for Wide Open Throttle's Revolutions Per Minute). For outboard motors, you want to be between 5,000 to 6,000 RPMs at WOT. For stern-drives, you want to be in the 4,000 range. For the other styles of inboards and jet-drives, refer to your owners manual as there are too many variations to give a recommendation. When you're testing your boat and at WOT, if you're not in the recommended RPM ranges, you know you're not at optimal performance. Granted, if your prop's damaged, it'll be misleading for your test so make sure your prop is in tip-top shape. The same can be said if the boat hasn't been maintained properly.
How to Overcome High Altitude ChallengesBefore I dive into this topic, you'll want to ensure the few variables with your boat.
- Make sure the prop(s) are in prime condition.
- If you don't remember the last time you had a tune-up, consider getting one.
- Run a WOT test on the body of water you visit the most often. I recommend running it with your typical boatload of people, gear, food, and/or pirate equipment. (Maybe not the pirate equipment.)