Who uses for gas skiers or wakeboarders

[woody]

Been trying to settle an arguement for a while now our club has two boats an X2 and a Prostar 190 both with 310hp engines - given the same time period who uses the most gas a skier at 36mph or a wakeboarder with full ballast at 21-23mph.

[sizzler]

from my experience with an X9 ..i use far less petrol ,wakeboarding (even with full ballast) than slaloming.....but it absolutely drains it at footin speeds........(mcx350)

welcome to the board

[Double Overhead]

Im gonna say the wakeboarder uses less fuel.

[woody]

mmmm wakeboarders are forever falling off and getting pulled out of the hole and back on the plane. skiers only fall a few times and the boat takes less effort getting back on the plane as no ballast, conseqently 'boarders use more gas overall is a theory I've heard banded about a lot, whether its right who knows

[shepherd]

I really have no idea but here's my theory. There's probably not much difference in GPH between a boat screaming along at 36 mph and an overloaded wakeboard boat plowing through the water barely on plane at 21 mph ( :cool: technically speaking, most boats have a "hump" on the power curve at "semi-planing" speeds -- where I think wakeboard boats cruise -- then the power curve steepens as the boat goes faster when on plane -- towards slalom/barefoot speeds. Also, weight has a big effect on power requirements/fuel burn). However, wakeboarders ski for much longer durations, so I'd think that the wakeboard boat would burn more during a full day of use.

Am I right Woody? You guys are in the best position to compare...???

[oxmach]

I've found it's the wakeboarding that drains my tank more quickly. I put this down to longer runs i.e. usually 20 min, plowing more water and as mentioned above more drops and starts. Just my observation on an X-7

[6ballsisall]

A scientific study of this would be interesting to see...

[jayderwin1]

some one should call myth busters!

[woody]

Our boats have different sized gas tanks and we're running on LPG from a large tank on site that don't have a flow meter....... really hard to figure it out. GHP who knows, you buy a car the man has to provide numbers in his literature (at least over here in Europe) but you buy a boat they just say fill her up when empty.

[sizzler]

where are u based woody??

[east tx skier]

A scientific study of this would be interesting to see...

Sounds like you're volunteering. I've already done my write-up for the year and don't wakeboard. Slalom sure does drink the gas though.

[MYMC]

3470 is baseline for a 2005 TT boat (no skier factor). A 2005 X-Star fully ballasted turning 3470 is running about 20 mph. The X-Star is going to win the fuel consumption contest (or lose depending on your perspective). The X-Star will require a greater amount of throttle for any given RPM with ballast on board. This is evidenced by the use of speed mode in wake boats...by using speed the boat increases the RPMs to maintain a given speed input (i.e. greater throttle angle a.k.a. more fuel). Also wake boats tend to suffer from "fuel wash" where the throttle angle is so great that the engine ECM is thinking that is should be running at wide open (after all the throttle blades are open that far) but the RPMs are only in the 3500 range. This leads to incomplete burn and raw fuel washing the cylinder walls. This removes the oil film and things get ugly from there.

Wake boats are almost always larger and heavier. They have more running surface in the water and as such more drag. So while they may be running slower it is a lot more work to do so

[FrankSchwab]

I hate to do this, but let's throw some real numbers into the mix.

Here (http://www.boattest.com/Yes-results-914.aspx) are BoatTest.com's test results for an X-30 with the MCX engine:


Test Results
RPM MPH Total GPH
600 3.9 .9
1000 5.7 1.5
1500 7.6 2.7
2000 9.1 4.8
2500 16.7 7.3
3000 23.7 9.5
3500 28.8 12.1
4000 33.2 15.4
4500 37.0 20.1
5050 42.3 26.7


Look at the difference between fuel burn at 23.7 and at 37 - it doubles! Being as we measure our fun in terms of time, and not in terms of miles traveled, GPH is a better measure than, for example, MPG which would take the speed difference into account.

Now, will full ballast tanks double the fuel burn at 20 mph? What percentage of an hour do you spend running when you're skiing? What percentage of an hour do you spend running when you're boarding?

/frank