Altitude Ajustments

[robertdodson]

So I have a G21 with the 409 engine. I live at a lake and have had zero issues in regards to power. I went to Lake Powell recently which is at 4000 feet and noticed a loss in power. I couldn't get the boat to plane with full ballasts and a boat full. I never have the issue at my lake which is at 1000 feet. Is there an adjustment that can be made for altitude?

[NautiqueJeff]

A different prop is the easiest thing, but it is pretty pricy for a location that you don't frequent.

[nyryan2001]

He has no recourse without going custom on the prop. 17x17 is it. With that tranny.

if you wanted to go custom.... Send that prop off to Nettles and have them make it a 17x15. It'd be quite a difference in hole shot. You'd lose 2-4mph off your top speed.

[DanielC]

Engines lose about 3% of thier horsepower, per 1000 feet. At 4000 feet, you are down about 12 % horsepower

[jhersey29]

I'm a slalom boat guy but curious. I was in Powell 2 weeks ago and live in Denver. Did notice top end increase in speed to 43 at Powell versus the lake at 6000 feet.. Why would you want a fully ballasted boat to plane? Isn't the idea to create a wake. All the surf and wake board boats I see stir the heck out of my local lake and I rarely see any of them on plane like a slalom boat. Sure makes it darn hard to ski a slalom course with power turning monster wake boats sending rollers up the lake.
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[robertdodson]

When I say plane...I mean get up to speed. I couldn't get past 14mph.

[nyryan2001]

Robert-

If you are gonna keep that boat, and go there often, and wanna go heavy... You have one option: drop pitch, ie take smaller steps.

Since the 17" props are so new, there is only one size, you gotta go custom. Alter the one you have now, or buy a second 17x17 and have it altered.

Or just go less ballast when you are there. On a side note.... The wave size, shape and quality at 22-23 mph with NO ballast, but NCRS at 5, is amazing. My skill will never exceed this!!