Steve Zuckerman

Just curious guys..........
Went cruising yesterday with the wife and another couple. 3/4 gas tanks and moderate summer load. All I could muster was 82 MPH (GPS) @ 5400 RPM with a 28" P-5X.
It was blistering hot (truck temp gauge said 96o) and humid. Lake water was 80oish. Light chop (pretty sticky)............
How does hot humid weather affect your boats?
I'm off 4 MPH from my best speed, and 2/3 off my regular loaded #s. Is there a formula to determine horsepower loss or gain by changes in temperature/humidity/elevation/
barometric pressure?
Maybe I'll throw some tubs of dry ice in the engine compartment for the next poker run ...............
Regards,
Steve

Magic Medicine

Looks like our theory has proven itself once again. Imagine what the numbers would have been if you didn't have the "after market" venilation. By the way, it must be nice to have some warm weather. It was in the low 70's hear all weekend with winds out of the North = no boating on the big pond.

sandcraft

Cold, dense air good. Hot thin air baaad.

Nordicflame

iTrader: (4)

In 123* at Lake Mead last 4th of July our Flame would run 77 speedo on flat water. 85+ speedo at Havasu in 90*.Quite a bit of difference.

Buddy's Heat at Havasu in 90* weather ran 97.1 (out of prop) with intake air temps under 110 with the Supercooler and BTW, no additional venting

Now try 110* at 3700 feet on smooth water and see what you think. Welcome to Lake Powell hell!

Dave

Steve Zuckerman

Dave,
The supercooler must do exactly that. AND, at least Powell looks like a beautiful hell ..............
Regards,
Steve

bobl

Hey Steve, Just got back from visiting your neck of the woods(Lake Cumberland). There was a little impromtu radar run down by the dam. I was able to hit 89.2. I think I'd of gotten 90 if I would have allowed more room before the gun. Speed was still creeping up. There was a nice chop, about 88 degrees and very humid. On the recent dyno runs I've made the correction has been about 8% in 100 degree, 50% humid and 1000' elevation. So, that's over 50 HP in your boat, or 3 MPH based on our 17HP/MPH formula.

Steve Zuckerman

Bob,
Sounds like you guys had a good time at Lake Cumberland. What did you think about the lake? Did you make it to 76 Falls ?????????
You must me making some serious HP to run 90 in this heat!
Your correction factor #s sound spot on as usual.
Regards,
Steve

bobl

We made it up to 76 falls a few times. Even swam under the falls...cold! It's a beautiful lake. We covered 350 miles in the boat while we were there. We didn't venture too far up the lake from the dam. There was quite a bit of debris in the main lake, that got worse the further you went. There weren't many boats out, even on Saturday. Sunday was forecasted to rain but it turned out pretty decent. The weather all last week was really nice. Cool at night and upper 80's during the day.

I cranked the timing up to 34 degrees (from 30) and it woke the engine up quite a bit. Still haven't raised the boost past 5 PSI though.

boatingbent

I was thewre with Bob and my Daughter took this Video
http://media.putfile.com/Bob-Lloyd

Steve Zuckerman

Bob and Bent,
Nice video. The boat looks awesome! I hear you about the debris. We had a stormy (including tornadoes), rainy May, and several of the area lakes have debris that are usually clear. The wind blew a lot of limbs and even trees into the Cumberland Plateau lakes, and the high water levels picked up even more shoreline debris. Cumberland is a HUGE lake. It's a shame you couldn't have seen more of it.
I hit something at Center Hill Lake (Cookeville, TN, 60 miles southwest of Cumberland) Memorial weekend and busted my upper gears .........no give with the XR hub. Funny thing, it didn't hurt the prop (blueprinted P5-X) at all........I thought a blade would have bent or broke before the gears broke?? Oh well, boat is an acronym for "blow off another thousand" ................
If you guys get back over our way, please let us know. We're having our local Poker Run here on Old Hickory Lake July 15th.
Regards,
Steve