XMP- 12 or 11.5- need advice

[Lakenut]

Hopefully my new XMP should be here any day. When I put it on are there any special tricks? How tight do you tighten the prop nut? Is there a torq spec to use?

[Lakenut]

Ok. My new 13X11.5 XMP arrived last night!!! Got the old CVP off this morning. What a PITA. It was on there pretty good. I sure was glad that I decided to get a puller. There is no way it would have come off w/o it. I got the new prop on. I use a new nylock nut instead of the old one and it was also a PITA to screw on. I see no way of it backing itself off w/o some elbow grease. Anyway, I followed the how to article from the old MBO. The new prop slides up to where the old one was. I tightened the new nut as tight as I could get it. I only got maybe 1/8 to 1/4 turn after it made contact with the prop hub. Is this tight enough? Do I need to go run the boat for 15 min or so and tighten again? Since this is the 1st prop change for me I don't want to screw something up. Does the prop "seat" itself further onto the shaft requiring the nut to be screwed on further to eliminate play?

[doughickey]

Wish I could help.... but I've only done this twice * myself.... so am interested in the answers from others as well.

(* Once to remove the CVP and install the OJ 13" X 11.5; the second time a couple hours later to take the OJ off, put the CVP back on, while I wait for the 13" X 12" to arrive.)

You're right about the prop puller. The old CVP was on pretty tight. I did what the MBO thread said to do... namely leave the prop nut ON. Glad I did. When the prop broke free, sounded like a gunshot and would have bounced off the rudder then my chest then the concrete if I hadn't left that nut on.

Looking forward to hearing your results with the 11.5".

Edited June 18, 2005 by doughickey

[edwin]

tighten it up when you install it...go ski. no need to retighten.

[Lakenut]

Ok. Got out this morning to try out the OJ. My results are not as scientific as others has posted so keep that in mind.

The XMP runs super smooth. I never had a problem with the old CVP in smoothness but there is a noticable difference. I was surprised that my WOT only changed by 50 rpms or so. I don't have a GPS but my speedo was showing a 1 mph increase in top end. At wakeboarding speed I picked up about 100 rpms for a given speed which made holding speed a bit easier. At slalom speeds I am running pretty close to 100 rpm= 1mph. Again I don't have stop watch numbers on accelration. My 2 and 1/2 year old daughter was along and she is not that patient. The boat was quicker out of the hole and the quickness could be felt on both ends of the rope. I also noticed less bow rise. Even with wedge and ski locker MLS. That might be because the boat planed out so much faster. In earlier testing w/ CVP I noticed that the wedge and ballast required the boat to increase rpms by about 150 to reach the same speed w/o ballast and wedge. The xmp required only about 100 more rpms w/ wedge and ballast for a given speed. that tells me that the prop was not working the boat quite as hard even though it was a small amount.

After taking a swim break and applying that stupid sunscreen in the areosol can I decided to take a slalom run to see how the prop performed at skiing speeds. I made my wife put sunscrren on the kid on the platform so the overspray would end up in the lake not the boat. Note to self....sunscreen on teak = slicker than s#@t. I sliped and bashed my leg on the platform as I fell into the lake. My leg hurts pretty bad and swole up so that ended the skiing day for me. I don't think it is broken but it is probably better to be safe than sorry and push a slalom run and get hurt worse.

One other thing I noticed is that the boat would run faster and more RPMS with more fuel. As the gas guessometer dipped below 1/2 tank I lost 50 rpms vs 2/3 full. I guess the extra weight in the back of the boat helps keep the nose up and gets a little more of the hull out of the water.

Final conclusions after 1 trip out:

WOT still around 4800rpms bassicaly no change

Slight increas of top sped

Aprx 100 rpms more @ watersports speeds

Acceleration much better

Less bow rise

SKier to skier says the 11.5 is a match for the 13 and they right in my case. Note that my results a a bit diffent than Edwins....just goes to prove that every boat is a bit different.

Edited June 19, 2005 by Lakenut

[mlange]

I don't know... that sounded like a very good write up to me.

[doughickey]

I second the motion! Good write-up. Thanks for the info.

Can't wait for my OJ replacement to get through Customs so I can try it out! (Was sent 1 1/2 weeks ago.)

[doughickey]

I received my OJ replacement prop today. (Finally got the 13" X 12" after returning the 13" X 11.5" they shipped in error.)

Now.... it gets a bit more confusing.

The 13" X 11.5" was marked as follows: (13 X 11.5 VC OJ 1 1/8). I interpret (guess) this to mean 13" diameter, 11.5" pitch, variable cup, 1 1/8" shaft.)

So far so good.

My replacement prop is marked: (13 X 12 VC .65 OJ 1 1/8). I interpret (guess) this to mean 13" diameter, 12" pitch, variable cup, .065" cup, 1 1/8" shaft.)

So..... now here's the questions I've asked. I'll post the answers.

1/ Did my 1st prop have no cupping? Was it avail with cupping?

2/ Is the .65 the "cupping" on my new OJ?

Now, I'm wondering, do they (OJ) have different cupping with each size of prop like ACME seems to have? If so, what are the options.... and who decides which one to send... based on what factors? Could I have received a 13 X 12 with different cupping? Their website doesn't say anything?

Regardless, I'll post my boat test results. Will be at least a few days from now.

Edited June 26, 2005 by doughickey

[martho]

OT:

Doug,

I have to know why you underline things in your posts. I go to click on them thinking they are links and they never are. I keep thinking the links are busted, but I guess it is not your intent for them to be links.

Just curious???

Back on Topic:

[edwin]

I received my OJ replacement prop today. (Finally got the 13" X 12" after returning the 13" X 11.5" they shipped in error.)

Now.... it gets a bit more confusing.

The 13" X 11.5" was marked as follows: (13 X 12 VC OJ 1 1/8). I interpret (guess) this to mean 13" diameter, 11.5" pitch, variable cup, 1 1/8" shaft.)

So far so good.

My replacement prop is marked: (13 X 12 VC .65 OJ 1 1/8). I interpret (guess) this to mean 13" diameter, 12" pitch, variable cup, .065" cup, 1 1/8" shaft.)

So..... now here's the questions I've asked. I'll post the answers.

1/  Did my 1st prop have no cupping? Was it avail with cupping?

2/  Is the .65 the "cupping" on my new OJ?

Now, I'm wondering, do they (OJ) have different cupping with each size of prop like ACME seems to have? If so, what are the options.... and who decides which one to send... based on what factors? Could I have received a 13 X 12 with different cupping? Their website doesn't say anything?

Regardless, I'll post my boat test results. Will be at least a few days from now.

<{POST_SNAPBACK}>

Shoot Max an email, you'll have an answer.

[doughickey]

OT: 

Doug,

I have to know why you underline things in your posts.  I go to click on them thinking they are links and they never are.  I keep thinking the links are busted, but I guess it is not your intent for them to be links.

Just curious???

Back on Topic:

<{POST_SNAPBACK}>

Oops sorry. When I want to emphasize a word, I know it's rude to put in caps. (= yelling) Sometimes I underline instead. You're right... becomes confusing. (So, I've replaced "rude" with "confusing". Not a good alternative.)

So, I'll not use CAPS, nor underline, but instead, use italics or color or bolding.

Guess you can tell I'm so old, my habits come from long before word processors and yellow highlighters.... when we actually wrote things by hand.

[Lakenut]

Mine had the 13X 11.5 VC on the back of the hub also. Hmmmm.....could that be why I got differnt results than Edwin?????

I am very satisified with the performance of my OJ even though I thought I would pick up 150 rpms or so at WOT. Oh well, I am still within the operating range and picked up performance in all aspects. I just find it strange that I pick up revs at skiing speeds but not @ wot. Guess thats why I dont work in the prop business. I don't see why the footers don't like this prop. Top end for me was better and when I pushed the throttle in while underway the prop responded right away. That is something my old CVP didnt do. I have a hard time imagining the Acme doing a much better job for the SLXi.

Oh by the way....All CVP owners....I knew I had a hairline crack in the leading root edge of one of my blades thus I needed a new prop. When I got the old prop off of the boat I noticed what appears to be cracks or something at the roots of all of the blades. Maybe it is just cosmetic imperfections in the casting process. I don't know. Here is the important part....I could not see this when the prop was on the boat. And trust me I looked pretty hard. If you are going to run your CVP (which I found to be a descent performing prop) take it off of the shaft and give it a good look over.

[doughickey]

OJ Update:

Not the 13" X 12" water test yet.... that won't be for a few days. This is about cupping etc.

I just spoke with Eric at OJ propellers directly. (1-800-359-9730). Great conversation. Great insight.

1/ The ".65" on the hub of the 13X12 prop is NOT the cupping dimension. He explains this is a measuremt that they take regarding the relative surface area of the prop vs the area of the circle covered by the prop. In other words, if you put the propeller flat on the ground, and looked at it from above, then 65% of the "circle" covered by the propeller has blade covering it. This is simply the best coverage they have found.

The key point is that ALL their props have the same ratio. They just haven't removed the ".65" from the manufacturing process. It shows up on the 12" pitch prop... doesn't show on the 11.5". But, they both have a ratio of .65.

2/ Cupping: Yes the OJ props have cupping. Eric explains they have found the most effective cupping is about .080. (80 thousands of an inch). This is what they use on their props. This "effectively" increases the pitch by a wee bit.

The key point here is that for each size of prop, they only sell one standard "cup". So, one 13" X 11.5" OJ is the same as any other 13" X 11.5" OJ. (Unless you specifically custom order a different cupping on your prop.)

3/ The prop being supplied to the Malibu Promo Boats is the 13" X 12" prop.

Lastly, Eric really appreciates the "testing" and "reporting" we do for each other on the Crew. As he explains, OJ does not have access to all manufacturers' boats and all models and all years and alll motors and all applications by Customers. So, the "test/reporting" we do is very visible and very valuable for him as well.

It's great to be able to talk directly to the folks who design & build the props we put on our boats.

So.... that's it for my prop report.... until I "test" and "report" on my 13" X 12".

[VinRLX]

The 13" X 11.5" was marked as follows: (13 X 12 VC OJ 1 1/8). I interpret (guess) this to mean 13" diameter, 11.5" pitch, variable cup, 1 1/8" shaft.)

<{POST_SNAPBACK}>

Here's one for ya: Why is a 13x11.5 prop marked 13x12?

[NorCaliBu]

Here's one for ya: Why is a 13x11.5 prop marked 13x12?

<{POST_SNAPBACK}>

I noticed that too but figured it was just done in error.

[Lakenut]

Made my second outing with the new prop a few days ago. Everybody's coment was about how smooth the prop ran. Good stuff!!!

Doug- glad to hear your findings. I thought that I would have to get another prop and test it too if the cupping was available in different sizes

[doughickey]

Here's one for ya: Why is a 13x11.5 prop marked 13x12?

<{POST_SNAPBACK}>

I noticed that too but figured it was just done in error.

<{POST_SNAPBACK}>

Oops. I have corrected my post. The 11.5 pitch was marked 11.5".

Sorry for the confusion.

[doughickey]

Here's my OJ 13" X 11.5" results. (Net is I am working to get it replaced with the 13" X 12").

MY BOAT: 1998 RLX; 310 carb; (posted redline by Indmar is 4800 rpm). Weight 2450 pounds. Main usage is skiing. No wedge. No fatsacks. Minimal boarding. 

BEFORE: With the CVP 13" X 13" stainless

Good hole shot, good midrange. At 4800 redline I got 47 mph (GPS). Top speed 49 mph (GPS) at 5000 rpm.... just past my redline

AFTER: With the OJ XMP 13" X 11.5" Nibral

Great holeshot, great midrange.  At 4800 redline I only get 43.4 mph (GPS). At 5000 rpm I get 45.4 mph, and have throttle left that I can't use. Would over rev the motor if I burried the throttle.

I'm not a strong enough or good enough skier to notice any difference in wake characteristics.

NET: I've got power left that I can't use.... and I'm revving higher than I have to for any chosen speed. I lost about 4 mph. The 12" pitch will be a better choice.

<{POST_SNAPBACK}>

OK, have tested the new 13" X 12" OJ XMP. Am very glad I sent back the 11.5" and got the 12".

Here's my results. All with 1/2 tank gas. 160 pounds of passengers. (My 2 kids.... one as scribe.... the other holding the GPS for me.) Also, this is a 1998 Response LX, 310 carb (supposed to be 4800 rpm redline). NOTE: This is not with a skier in tow.... so not a true test of towing performance.... however, you can tell the prop has more punch than the CVP through all rpm ranges. I couldn't honestly tell the difference between the former 11.5" and this 12" pitch in the seat of the pants... but I do like the lower revs with this one. And so smooth....

At most board/ski towing speeds (20 mph - 36 mph), the rpm and speed are almost bang on 100 rpm for every mph. At the high end, the hull just is pushing too much water, so more rpms don't quite yield a lot more speed. I still had some throttle left to play with, but I really don't like taking the old carbie past 5000 rpm. NOTE: For those with the Monsoon or HH, with a higher redline of 5200, you'd get even better top end!

NET: I'm really happy with the performance of this prop. Smooth, great acceleration low and mid range, OK top end, and lower revs (about 200-225 rpm for the same speed) than the 11.5 for (I think) equivalent performance.

In each case below, the first number is the speed (via GPS), the second number the rpm.

5.4 mph 700 rpm lowest idle speed

18 2025

22 2250

25 2500

30 3000 (Note: with the 11.5", this was about 3200 rpm)

34 3400 (Note: with the 11.5", this was about 3625 rpm)

36 3600

40 4100

45 4800

46.2 5000 (Note: I need to test this rpm again. Each time I got up to this rpm range, we got boat traffic or ran out of lake, so I think this may be a bit low. Also, I still had a bit of throttle left...)

Obviously the true test is from behind the boat..... but this one feels real good. Happy camper now!

Since it was just me and the 2 kids this past weekend, not an exhaustive set of tests (ie: no test with a skier, or boarder)... maybe later this month!