Update: Boat gas usage per set

[rwskier]

Hey guys,

Many of you may recall this discussion last year in regards to a 200 Nautique. Since February of last year I have been running the 422, which is the 12.5 x 15.5 prop on our boat. After receiving the final gas billing for the year here are the stats. 378 sets, 500.2 gals, I believe that is 1.32 gal/set. That is a huge difference from the prior year at 2.02 gal/set with the 12.5 x 14.25 prop. I am having a hard time believing it myself but that is how it is penciling out. We had 2 seasons with the 2010 200 and granted it may have loosened up some but 2.02 to 1.33 per set.

I am curious how things have gone for others this year with the 200? Maybe our sets were shorter this year considering we are getting older and all!

[dahlnova]

How many passes per set?

[rwskier]

Min 6, max 8, varies a little but usually right there.

[dahlnova]

Thanks!

[dahlnova]

We had 2,875 passes & used 611 gallons, .21 gallons per pass

2006 Malibu

 

[auskier]

@rwskier is this with a 5.7 or 6.0lt?

[skierjp]

The problem is if you're a tournament skier you won't get the 422! I think it would be a better comparison if it was hours to hours.

 

[skierjp]

How many passes were full passes or maybe falls at 1 or 2 ball? What about speed? Bad comparison.

[Ham_Wallace]

With a Malibu LXI, 5.7 Monsoon. 1 mile drive to ski course, 4 34 mph sets, 5-6 passes per set. 1 mile back to ramp. 2 gallons mid-grade used. Haven't measured the 6.0 litre but might be a touch more, not enough to worry about. 36 mph sets are a different matter.

[LeonL]

@skierjp, you won't get the 422 but an Acme 12.5X15 (whatever Acme number that may be) is approved for use in 2012.

[rwskier]

@dahlnova that is just about dead even to what we were experiencing with the 200

 

I should have said that it was a 5.7L engine. 98% of the rides behind this boat are 34 mph.

 

@skierjp we don't really worry about short passes. I would think that if you went down early, the fuel used to return to you and get back to the end of the lake would equate to a full pass. I try not to get to scientific about our set's or passes or it just takes the fun out of the skiing.

 

@Ham Wallace I am hoping that is 2 gal/set or that is some really good fuel economy.

 

I understand that it would be worse with the 12.5 x 14.25 but we don't track the fuel usage at tournaments. the boat shows up with a full tank and returns home with a full tank.

[A_B]

@rwskier, can you note your rpm drop at 34 or 36 mph? What rpm do you get at WOT now? Thanks

 

[DW]

What is the RPM comparison between the two props? There will be some improvement in FE once the engine is broken in, so that will account for some of the difference. You could calculate how many fewer times the engine has to spin over given the different pitch of the prop, you could assume the slip is equal for both. There will be a significant difference between an aborted pass and a full pass if it happens early, I would use a 2 to 1 ratio (example: a race car gets three yellow flag laps for every race lap when computing fuel mileage or distance to empty). It won't be as dramatic, but a boat under load at 3500+ rpm is using a significant amount of fuel (energy).

[rwskier]

@AB The good news is the boat has been delivered to it's happy new owner, the bad news is it left with the 12.5 x 15.5 prop on it. We have taken delivery of our 2012 but being a promo boat it comes with the 14.25 prop on it. The 2012 is running 3950 @ 34 and 4190 @ 36. As I recall on the 2010 with the 15.5 it was running 3600 @ 34 and 3875 @36. I am pretty sure that I have never run the boat WOT I'm just not in that much a hurry to get to the other end of the lake.

[A_B]

@rwskier, running at WOT is actually a good way to tell how your prop is performing. If you don't rev up in the manufacturer's specificed range, you can be loading the engine too much, or if you are over-revving, you can re-reprop and drop fuel consumption. I was just curious to see how that prop switch was loading the engine. The 34 and 36 mph rpms sound more reasonable, and I bet the pull might have felt better as well. I am thinking a high revving boat would be a little more harsh, just a hunch, no scientific proof.

[rwskier]

@AB It's funny but I can't even remember the last time that we turned off the Zero Off. Just such a habit to go ski and park the boat. That what happens on private water I guess.

 

The pull of the boat felt so much better with the 15.5 even though it was not approved for use last year. This year they have allowed any combination of prop/engine that is approved to be used in tournament. It looks like I can run a 12.5 x 15 this year and be legal. All I have to do now is spend another $400 for a different prop. Dang

[cotton]

Thanks for this info rwskier. My 2009 206 with PCM 343 and 422 prop burned about 1.2 gallons per set on average. I've never kept up with it on our 200, also with the 343 and 422, but thought it was pretty close to the 206. At $4 per gallon your numbers indicate we are spending about 48 cents more per set than with the 206; and I can live with that.

[Razorskier1]

@rwskier Those RPM numbers are insane! At 34mph my Mastercraft runs almost right at 3400. At 36mph it runs 3650. While I think the 200 skis really nice, I can't believe how hard the engine gets flogged to just slalom ski. Heck, if I'm running 4190 RPMS I'd be pulling a barefooter!

[JC McCavit]

Just for clarity, when you are talking about the 15.5 and the 14.25, specifically which model number are we talking about? I assume the 14.25 is 422 or 668 with more cup but I am not 100% sure. I have no idea as to the 15.5 as this is the first I have heard about it. I am wondering if it would improve my fuel economy on my 97 Nautique. FYI, I will be skiing behind rwskier's 2010 200 at its new home here in Alaska in about 6 weeks.

[rwskier]

@Razorskier1 I agree that they are insane but that is just the reality of what CC has done with the 200. there have been many discussions about this subject and we have found that the 422 prop 12.5 x 15.5 works much better on the boat both rpm wise and ski wise.

 

@JC McCavit I believe that the 422 is a 12.5 x 15.5 and the 668 is 12.5 x 14.25. Your 97 probably is running a OJ propeller and I don't think that you will improve much on fuel economy with a different propeller. anyone chime in if you have found out otherwise.

 

That is great that you will get to ski behind my old baby, it is a great boat and I sent it up north with the 422 15.5 on it.

 

also as a promo boat I will be able to run in tournament this year the Acme 12.5 x 15 but I am not sure what number that is. I don't have one yet but more than likely pick one up and see how it works. Certainly will report once that happens.

[JC McCavit]

Thanks Russell, I am running a 422 on my 97. Have also run the 668. I guess I am confused on the diameter. Which prop is the 14.25 that came with your 2010 promo boat?

 

422 12.50 15.500 0.105 cup blades 4 1" RH

 

668 12.50 15.500 0.150 cup blades 4 1" RH

 

http://www.acmemarine.com/prop-list_ski-boat.php

 

[rwskier]

Guess I was confused as well, according to the chart the 14.25 is a 1868. Sorry about that, too many freaking numbers dang it.

 

So the promo boats come from the factory with the 1868 12.5 x 14.25. Our 2010 200 I put a 422 12.5 x 15.5 and that is what is on the boat that is now in Alaska.

 

Thanks for getting that link to Acme.

[skierjp]

Leon, the 422 is not approved. Nautique offers it as as a recreational prop only.

[A_B]

34 years of supporting SN have been on hold since 2010. Nuff said.

 

[ForrestGump]

Skierjp, I guarantee you've gotten 200's at tournaments with the 422. It's just not something that's checked.

[jdarwin]

@ShaneH - really? Shocking!

[Roger]

It's checked at EVERY tournment I ski in. Where are you skiinig that it's not checked?

[Jody_Seal]

We all know that the propellers on all these boats are on their not for the betterment of the skiers but for the reason of having to make the drag race at towboat tests. A function of towboat testing that does not coral-ate to how these boats are utilized under tournament conditions. The idea of mandating what propeller is to be used on a boat in tournament should be up to the owner of the boat. After all if the boat does not come up to the bar during tournament conditions the boat should be put back on the trailer and another utilized that that does. No two boats can or will ever be the same under any conditions due to the fact they are made of fiberglass and built by hand, so whats the big deal? Glad you guy's are reporting back real world findings of how these boats run (in whatever configuration) and your experiences with them.

[bmiller3536]

I cannot wrap my head around the reason for dictating what prop's are 'approved' for pulling tournaments. I mean honestly did you get a 16.08, 16.95 or whatever the actual time should be? If so then who cares what prop was on the boat

[Alberto Soares]

My 200 with 6.0 runs 3800@34 with the 422, used to run about 3900 with the original 668, our lake is about 1500m (4500´) high and the only gasoline available is 20% ethanol.

[A_B]

Is there some magical prop out there that can make me ski even 10% better? What am I missing? I would change my prop in a heartbeat.

Who the flip cares what prop is on the boat as long as it doesn't send up a rooster tail or something odd from a deformity?

 

If the skiers at a tournament accept it, then go ski.

[LeonL]

@skierjp, I know that the 422 isn't approved and didn't say that. I just said that a 12.5 X 15 (whatever number that is) is approved for 2012.

@AB, I gave a flip last year on some MasterCrafts. There were different props used on MCs that made them ski quite differently. Jody can confirm this, but my understanding is that a prop change early in 2010 was made to give the 200s a better jump pull.

[Jody_Seal]

I really did not keep up with MC's prop usage last year. I know we had a couple of units at our tournaments that were bears to ski with and drive yet I also received a couple to drive in tournaments that were very nice rides to drive and ski behind. MC was chasing their tails last year with the jump program many glitches and revisions for MC jumping in 2011.

AB a propeller can make or break the skiability or feel of the boat to a skier. Changing from a four blade to a three ( or visa) can set up handling/steering issues unless rudder adjustments (rudder tuning) are made, this can impact the skier due to how well the boat tracts down the course. different prop configurations can impact lift under the boat and how the boat carry's the bow. Bottom line is the boat should not negatively impact the skier in ways such as tracking and harshness of pull. Different blade profiles have different slip characteristics. ACME'a have a lot of inherent slip vs that of a OJ due to blade profiles and cup. These higher revving boats seem to need the increased slip to get them up and running down the lake. These boats are far heavier and are not the efficient tournament ski machines we used to utilize in tournaments and day to day skiing.

Keep in mind a internal combustion engine is nothing more than an air pump, when the air pump is winding tighter and running at higher rpms to pump air it is also requiring more fuel to com-bust and utilizes the fuels energy to do so. So it makes sense that the lower RPMs you can run the engine will utilize less fuel.

Finding the combination for all this is akin to alchemy especially when one throws in the acceleration numbers that these boats have to adhere to from towboat tests. I know of one industry engineer that would like to see this test either eliminated or radically softened up as the test does not realistically represent how the boats are utilized in tournament conditions.

[ForrestGump]

Roger, the only place in the SCR that I've seen the prop checked was at the Big Dawg to make sure the boats were identical. We even had the chief driver at nationals tell us a few years ago that they don't check the props.

[Roger]

@ShaneH - Wow...

[skierjp]

ShaneH - I guarantee I haven't. My neightbor uses a 422 on his boat and it's a dog. I'm with Roger, I check the props here in Central Florida.

[jdarwin]

@Roger - It's checked at EVERY tournment I ski in. Where are you skiinig that it's not checked?

 

Please elaborate. How can you tell the prop is stock/approved? Visually? Often, the model number/pitch/diameter imprint is hidden behind the prop nut. Do you take off the prop? How do you know the stock prop has not been modified? I used to take my OJ's and have them balanced. That used to involve the changing of the pitch/cup to some degree. Unless you have the ability to interpret a cad drawing from Acme or OJ, there is no way to visually determine IMO.

[rwskier]

According to the official approved list there are only 2 props approved for use with the 5.7 l

 

*Correct Craft Ski Nautique 200 Unmodified

 

PCM Excalibur 343 (5.7L)/1.23:1

AC, 4, 12.5 x 14.25 Nibral

AC, 3, 13 x 14 Nibral

 

PCM ZR409 (6.0L)/1.23:1

PCM ZR450 (6.0L)/1.23:1

AC, 3, 13 x 14 Nibral

AC, 4, 12.5 x 15 Nibral

 

*Note: Boats approved with more than one engine and/or more than one propeller may use any approved combination in sanctioned tournaments.

 

 

[The_MS]

After a record is set, the prop is removed and sent in with the video.

[The_MS]

The promo guys would luv that.

[A_B]

I know there is a difference between an OJ and an Acme, as well as a 3 vs 4 blade, but I'm talking about a 422 vs 668 and why an owner can't use one if not certified by the test. Is there that much difference in the pull between the 422 and a 668? I'm seeing posts on lower rpms and lower fuel consumption (at probably some sacrifice of hole shot). Not that someone now runs 4 buoys better.

 

I guess I am a tea bag throwing independent and don't like all the rules and regulations thrown out for marketing purposes.

[DW]

I can understand a logic for having the prop be part of the approved package for a tourny ski boat, it does or can have significant impact on performance. If by chance, a different prop makes a particular boat "easier" to ski behind and the results from that particular event have an effect on other events which could affect invites to national events, so it makes sense to control the entire boat package.

 

What would make more sense would be to update the testing requirements and approval criteria to make sure the tests are reflective of real use and issues such as fuel consumption are considered as having a level of priority.

 

As a racer, I can't imagine that it will take very long for a particular boat to show up with a given prop that is actually marked differently. . . . that wouldn't happen would it!!!

[Onside135]

Only if these guys show up to your lake...

[ForrestGump]

I know for a fact that one boat used at Regionals did not have the right approved prop. It came from CC with the 6.0 prop on a 5.7 and it stayed that way all year long.

 

FWIW, CC told us that they submitted the 422 with the 5.7 200 but it was something like 2 ft short on the 35.4 to 38.2mph jump acceleration test. It passed the 0 to 36 slalom acceleration test without issue.

[DW]

Another element in "testing" is whether a true production boat is sent to the tests. We all know that in the days of car tests, the manufacturers all sent "blueprinted" examples of the vehicle being tested . . . Not sure that the boat companies do that but with the build variablility of a fiberglass hull it could certainly make a difference. Boat companies probably don't have the financial resources to actually do something like that.

[ForrestGump]

There have been cases of manufacturers reworking boats with more hook using bondo or taking hook out at tests, before. It's allowed.

[bigtex2011]

Boy, I'm with Shane, bad brad and joe d. I feel like i work my tail off to scrap my way into or if i'm lucky out 38. (believe me, it aint pretty). doesnt the awsa have more pending issues than to check and see if the prop is a 422, an 1868, or a ou812. the point is, mastercraft, malibu's and corret crafts all run different rpm.. i cant imagine that the awsa cares how many rpm the sn200 turns. the lower the better. as long as u get 16.95 and the splits are right, then case closed.. we just got a new sn200 at our club sight. i got to be honest with you, i miss the 196. i feel sorry for the guys stuck below 28 off because they get way laid with that wacky 28 wake. the boat sounds like ur going a hundred mph .. i cant wait to make it to joe's tourny and try his carbon pro out. and the mastercraft at regoinals in cypress was butter.

[6balls]

No idea on RPM, but first SN200 I skied was skiwatch in FL fall tourney and felt like it was THE game changing slalom boat in terms of wake (opener 28 off, biffed mid 38). This was the very boat that pulled the men's pro record. Skied another 200 the following season and was surprised that it didn't seem any better than the other big 3's...maybe worse. Was told the difference was the prop.

[Roger]

@jdarwin - Please elaborate. How can you tell the prop is stock/approved? Visually? Often, the model number/pitch/diameter imprint is hidden behind the prop nut. Do you take off the prop? How do you know the stock prop has not been modified? I used to take my OJ's and have them balanced. That used to involve the changing of the pitch/cup to some degree. Unless you have the ability to interpret a cad drawing from Acme or OJ, there is no way to visually determine IMO.

 

As Chief Driver, I ask the promo owners what prop is on their boat. I suppose they could lie. If they don't provide the info, I read the numbers on the prop. I've never not been able to read them though I agree that if some work has been done, it might make it un-readable. I looked at three boats as we pulled out of the lake today and could clearly read all three. Personally, I always know if someone is running the "other" prop in a 200 because of the lower RPM.

 

I'm not pro or con on the prop change, just like to follow the rules as an official. I agree with Jody's assessment of why the props are what they are...

[skierjp]

422 ( 5.7 liter ) is stamped on the prop near the nut you can see it very easy

654 ( 6 liter ) is in the same place.

These are the only 4 blade props approved by AWSA. I'm not sure what the nember is for the 3 blade but it is usually only used for jump with the 5.7

The 422 is now available for Recreation use only.