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Not your typical prop question


martho

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Take 15 adults, put them on jumpers, get 15 ropes all hooked up to the pylon. Someone yells hit it and what happens.... not a thing.

This was the situation about 10 days ago with my cuz' 2006 RLXi 340 Monsoon with OEM prop. The boat was turning 2900 RPMs, but would not even begin to lift the bow up out of the water. The boat wanted nothing to do with pulling up 15 skiers. Sure, there was some forward progress, but no way was the boat going to get up out of the water.

So, they go down the shore a few and grab the 08 RLXi and hook it up to start all over. Unfortunately, same result.

This is a regular thing at his lake and has been done with multiple previous 'bu model...Euro F3, Sporty, Response. Positioning of the ropes has never been an issue before. All on the pylon, some on the transom and some on the pylon, some on the fly hi, some on the transom...it hasn't mattered in the past.

Let's eliminate the following posts before they are made.

1. Yes, the RLXi is a heavier boat than the sporty/Euro/R. I know the RLXi plows a bit more water than those models, too.

2. I'm not interested in your observations that the pylon is going to be removed from the boat from the stress of 15 ropes. All under control.

3. There are photos of this being done before(all deep water starts) so it can be done and has been done.

4. These are not 250 lb wally skiers who have no idea what they are doing.

5. Yes, show teams use double and triple OBs on Hyrodynes to pull multiple skiers...but we want to do it with the RLXi.

Now, let's get to the heart of the matter.

Is there any way to go to an aggressive prop or even a 4 blade to get some pop out of the hole?

13x11.5 or have Eric/Bill make something with the pitch and cup we need?

Is it critical to get the ropes attached to the transom eyes to get some weight shifted to a lower area of the boat to help get the bow up?

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15 skiers out of the water quiet a view

a 'sitting' dock start may be easier

out of my experience with multiple skiers there some factors:

- hull (an old Ski nautique pulls pyramids well while the Barefoot not)

- transmission type makes huge factor sometime on diff serial #

- how easy and fast the skier starts (pop out of the water)

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Ive pulled up to 12 off the pole with no problem , power or pole , but my boat is a 400 hp 6.0l 13x11.5 prop and 3300lbs, Ive used acme and oj props , the acme is alot smoother out of the hole and top end.

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Did you just put the throttle down?

What if you give very Little throttle to start. Add power as boat starts to move. Gently you do not want to get cavitation started around the prop. Just a thought never pulled more then four skiers. Dontknow.gif

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ACME 515 13x12

Okay, well that blows my theory out of the water. I was hoping that you'd say that the RLXIs had bigger props on them. Problem solved! But no....

Did you have a similar distribution of ropes on the pylon, transom, etc? My own experience is that getting the ropes on the pylon vs. the transom allows the boat to plane out faster & easier, but I would think that you would have thought of that one.

You could try the old circle method (it would be hard with that many skiers though)....

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Did you just put the throttle down?

What if you give very Little throttle to start. Add power as boat starts to move. Gently you do not want to get cavitation started around the prop. Just a thought never pulled more then four skiers. Dontknow.gif

my first thought aswell.

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I need this same info too. This summer my ski partners & I started the war of who could tow the most kids. Mine a 2003 w/ Monsoon, other guy a 2003 w Vette, third guy a 2007 w Monsoon. Started with mine pulling up 6 kids (lightest 70 # to heaviest at about 140#) and it felt like a standard slalom skier resistance. Vette boat has more pop and he yanked 7. I pulled 8 and that amount started to work the boat and I could feel what I thought was cavitation starting but the motor was pulling no problem. Guy with the 2007 tried 8 last weekend but only 7 held on (he cant stand to be in 2nd place so I know he's going to keep trying - looked like the boat pulled them up with no probs though. We all have Acme 515's.

I figure next summer it's on big time so I need to get the edge in the prop department. I have the edge in qualified skiers with probably 12 and I'm not sharing.

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Just prop down guys. 13x12 will definately not do it, as Martho found out. The next prop, a 11.5 will likely not be a big enough step down. I'd recommend trying a 13x11 with lots of cup, say .120", or going to a 4 blade. Acme is not believers in the 4 blade for their 3 blade has more surface area, but the issue here is actually too much surface area.

The load on the boat is exceeding the horsepower needed to spin that size prop into the rpm range needed to accelerate. The magic number is finding the prop with the blade area and pitch to provide a low enough resistance to the load to let the engine spool up, but not so little as to either burn a hole in the water (cavitate), or not provide enough top end.

We have run some special props on RLXi's for the local show team, and I believe it was a 13x.11.5 with the .120" cup. All of their larger loads were off the dock with a good hit, (boat's moving), so it still may not be enough for what you're doing. I think the 4 blade may work better for heavy loads, for the smaller blade area I "think" helps let the engine spool up.

I would get Bill Weeks take on this from ACME. The data you already have with the max RPM is info he will need to know. ACME is 1-888-661-2263.

Peter

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I need this same info too. This summer my ski partners & I started the war of who could tow the most kids. Mine a 2003 w/ Monsoon, other guy a 2003 w Vette, third guy a 2007 w Monsoon. Started with mine pulling up 6 kids (lightest 70 # to heaviest at about 140#) and it felt like a standard slalom skier resistance. Vette boat has more pop and he yanked 7. I pulled 8 and that amount started to work the boat and I could feel what I thought was cavitation starting but the motor was pulling no problem. Guy with the 2007 tried 8 last weekend but only 7 held on (he cant stand to be in 2nd place so I know he's going to keep trying - looked like the boat pulled them up with no probs though. We all have Acme 515's.

I figure next summer it's on big time so I need to get the edge in the prop department. I have the edge in qualified skiers with probably 12 and I'm not sharing.

Good thing the 2007 guy doesn't live on my lake--we'd have serious competition going. Crazy.gif

Day before labor day I pulled 5 adult slalom skiers. It felt like it took forever to get them up, but watching it on tape, it didn't take that long. Didn't really feel cavitation on that one.

Labor Day we lined up 10 skiers: 7 adults, 3 teenagers. Three of the smaller adults were on JR. Skies. :Doh: After my wife knocked out the neighbor kid, we had 8 skiers up and circled the lake. There were two attempts--first I rolled into it and felt the cavitation, but continued to advance the throttle. Second attempt I rolled in and hesitated when I felt the cavitation and allowed the boat to gain more momentum before adding more throttle gradually. Prop: ACME 13x11.5 3-blade.

The record on my lake is 13 skiers, deep water start. Next year I'm going to be looking for all the wide combos I can find, ditch any and all Jr. skis, (maybe borrow a 4 blade prop from Peter?), and leave my wife to take pictures. Biggrin.gif

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