high elevation boating?

[mar]

Planning on taking my 15' fiberglass boat to a 4500-ft elevation lake this weekend. It has a 2006 yamaha 4-stroke outboard.
I've done some research and understand that there will be performance degradation due to the elevation. This will be my first time running the boat up high and would like some general comments/advice from the folks here on what to expect.

1. Rough how much loss of power can I expect from my outboard?
2. Will I be able to get on plane ? I'll be fishing with a buddy
3. Any potential damage to the outboard when operated at that elevation without making any tweaks to the motor and prop?
4. Any other tips and advice?

Thanks for the help.

Mar

[Bill Kiene semi-retired]

If your boat is not close to over loaded down here or under powered, I don't think it will be that big a deal.

If your boat is fast down here and gets on plane easily I think you will be OK but will feel some power lose.

I have that same exact motor that has carburetors but the new ones are fuel injected now.

I hear that fuel injection is better for altitude changes because it has some ability to adjust the mixture levels with the computer system.

Some use a smaller prop to get more RPMs at altitude or reject the carburetors if you are at that altitude all the time.

.

[Troutstalker55B]

For Lake Davis (5,800ft) I had to put on a 11 x 9 prop on my 40hp 4 stroke Merc. I have forgotten what size the stock prop was but it would not plane.

[mar]

Thank you gents. I'll give it a shot and find out what she can do. We'll just go at idle speed worst case. At least we'll be out of the cold water. And if it's something that I might want to do more regularly, I'll look into getting another prop.

[mar]

Well, got a chance to take the boat out at 4500-ft elevation. I would say that she did fine. At lower elevations, she can do 30mph at 5400 rpm wide-open-throttle, with 2 people on board. At 4500ft, she did 4700rpm at 24mph. So there was some power loss as expected and it took a bit longer to get on plane. Most likely need another prop if I end up fishing at even higher elevation to get the RPM's back up. All in all, not too bad.

Oh, and we caught a few of these in the process: :D

http://i255.photobucket.com/albums/hh134/mar224177/DSC_0253b_zps27740f49.jpg

[Troutstalker55B]

Good to hear and I'm glad it all worked out for you, Nice fish too! What size motor do you have? For my 40 at lake Davis I do 24 mph at 5800 rpm with just me, fully loaded about 21. I miss being on my boat and can't wait to take it out of storage to tell you the truth! Good luck out there.

[mar]

Good to hear and I'm glad it all worked out for you, Nice fish too! What size motor do you have? For my 40 at lake Davis I do 24 mph at 5800 rpm with just me, fully loaded about 21. I miss being on my boat and can't wait to take it out of storage to tell you the truth! Good luck out there.

I have a 2006 40-hp Yamaha 4-stroke. I suspect I’ll probably get the same numbers as you if I switch to a different prop and run it at Davis.