Prop removal questions...

mdvalant wrote: I'll work on getting some numbers. I never have time for fiddle faddle I just kinda wing it and go by what feels good to me. Had the 422 on the sport yesterday after a full recondition from ACME and I didn't really like it all that much........ 654 still my favorite though by far. If my memory serves well none of our props were under the 44mph mark on GPS. They were all 44-45 with one driver and rider full tank of fuel.

Mike what rpms were you seeing with the 422 at WOT??
My 422 is just back from the prop shop also so I wanted to get the numbers before I get a chance to hit some more debris. It is a better prop than the OJ 13 X 16 smoother and does reduce rpms at skiing and boarding speeds. The OJ is quite a good prop for this hull and does produce a slightly better top speed. It also handles small hits from debris better than the ACME. Both props have plenty of pull, the ACME is slightly better. We never use it to pull more than 3 people so never have the need for less pitch like your application. How many rpms are you seeing at 36mph with the 654?

Tim maybe it is a slow hull. My thoughts were the 1442 being a 3 blade may have a higher top speed. If it has the same rpms as the 470 though it will not be that usable (5200rpm). Tim do the 470 and 1442 tend to run the same rpms versus speed? What do you think of the OJ 428?

The speed numbers with 400lb ballast did not change very much(less 0.5mph). The attitude of the boat did not change much either, it still ran very flat. Almost zero bow rise when you go WOT. This was one thing I really noticed going from the 89 2001 to the 98 Sport almost no bow rise on take off.

Have never paid much attention to where the water breaks on the hull but I will next time. Maybe I should have added 2X 400lb bags and see if that gets anymore of the hull out of the water.

lewy2001 wrote: Tim maybe it is a slow hull. My thoughts were the 1442 being a 3 blade may have a higher top speed. If it has the same rpms as the 470 though it will not be that usable (5200rpm). Tim do the 470 and 1442 tend to run the same rpms versus speed? What do you think of the OJ 428?

The 3-blade vs. 4-blade argument is secondary to propping your WOT rpm's to your power curve. The 3-blade will have an advantage, all things being equal... but if it puts you 200rpm further from your hp peak, then things are NOT equal. I wish Acme would make a few 3-blades larger than the 470 and 1442 for the 1.23's, as the higher powered boats (HO 351w's, 6.0L's, etc) could benefit from one. Boats like the Crush and Joe's stroker only have 4-blades to choose from. I doubt youre going to do better than the 422, based on the RPM's youre seeing with it.

Ive never tried the 428, but Id like to. Ive tried the 430 (428 with extra cup) and I really disliked it on both my '90 and the Crush. I believe the 428 should turn very similar RPM's as the 668 Acme (which is a 422 with extra cup), or maybe a touch less. Even the Crush couldnt turn the 430 (~5200rpm, vs. 5550-5600 with the 668). I doubt the 428 would be the hot speed prop though, as OJ's tend to make the boat run a little more bow-down. Might be a good choice for slalom.

lewy2001 wrote: The speed numbers with 400lb ballast did not change very much(less 0.5mph). The attitude of the boat did not change much either, it still ran very flat. Almost zero bow rise when you go WOT. This was one thing I really noticed going from the 89 2001 to the 98 Sport almost no bow rise on take off. Have never paid much attention to where the water breaks on the hull but I will next time. Maybe I should have added 2X 400lb bags and see if that gets anymore of the hull out of the water.

Sounds like youre seeing all the tell tale signs of a slow hull. On my '90, I get zero bow rise. Adding weight to the rear seat helps very little. With 4 people across the back, I am lucky to pick up 1mph. The hull is just planted, and its a lot to overcome. Check and see where the spray breaks... if its at the windshield or further forward, thats your answer!

TRBenj wrote: The big discrepancy between the speed and RPM would suggest that you have a slow hull. Where does the spray break when youre at skiing speeds (30+)? My '90 also has a slow hull... runs very nose planted:

Tim, now looking at your photo compared to the only photo I could find of my SPORT running at or around 30 mph and WOW what a difference. It almost appears your spray breaks in front of the windshield, while I can't see exactly where (in relation to the windshield) it breaks on the SPORT, it is definitely aft of where it breaks on the 90 SKI. Also, there is probably some variation due to water conditions, but still the difference seem pretty big.

TRBenj wrote: Sounds like you are seeing all the tell tale signs of a slow hull. On my '90, I get zero bow rise. Adding weight to the rear seat helps very little. With 4 people across the back, I am lucky to pick up 1mph. The hull is just planted, and its a lot to overcome. Check and see where the spray breaks... if its at the windshield or further forward, thats your answer!

Just went through all my pictures and videos and they are all from inside the boat. Will make sure I get some of the boat at speed next season. Tim do you think a trade off from a slow hull maybe a better slalom wake?

I agree my rpm numbers are good so the 422 is the right prop keeping it just under 5K. Would be nice to see 45mph though. Was hoping a 3 blade may help but with less pitch than the 422 that is not likely without seeing excessive rpm. Tim a three blade 12.5" prop with 15.5"-16" pitch would be a nice option if available. Looks like I have a excuse now for wimping out on the barefoot experience.

Steve and Mike get some numbers and pictures of the boat at say 30mph 35mph and 40mph to match your prop testing numbers. This would provide some real nice reference material for all us Sport owners. Hey now that Keith has one you will be helping him out as well.

My contribution....Thanks again Mr. Morfoot for the pic.

Our windshield is back another 9" so I'm guessing it's worth at least another MPH or 2?

Agreed- 40mph is all you need to barefoot. 43+ with a footer is only needed if youre a BIG boy or doing 1-foot stuff.

Chris, that picture is worthless (as far as judging running attitude) because of the water conditions. Cool pic though! Similarly, the Crush doesnt normally run *quite* this bow-high.



Mark, youre absolutely right- a 12.5x15.5 or 12.5x16 modern CNC 3-blade would be great to try, as it might give you close to another mph. Too bad no such prop exists!

I would absolutely say that yes, the up side of having a "slow" hull is that because the nose is more planted, the slalom wake is improved. I think it helps the barefoot table a bit as well, as the turbulence behind my '90 is much more manageable than it was behind our former '92.

mdvalant wrote: Wow there is not much of that crush in the water

Its bouncing due to the water conditions and weight in the back. Just a well timed photo. It was to show that a single snapshot can be very misleading.

skutsch wrote: I have seen 'Dyne's riding like the bass boat above. Mike, thanks for the info on the prop, What I would like to do is plan a day to come down and pick it up in the plane (and get you your airplane ride). Then I would run it up here on a couple of boats, collect data and then bring it back. Looks like I am going to have to get working on the schedule. Will that work?

YES!!!

Let me know what kind of dates you're looking for and I'll let you know what's going on. I know we're out of town...June 9th I think it is. But yea, let me know.

Where did you have the fatsacs?

Thats the right place for them (unless you can get them further back like in the trunk or on the platform). It doesnt sound like you sped up at all? Does your GPS only read in 1mph increments?

I think your tach is lying to you. A 422 will run closer to 1:1 on a lighter Ski Nautique at skiing speeds. It will still overturn by a good margin at WOT (by nearly 400rpm. ie, 46mph @ 5000 rpm). I dont buy that a larger/heavier Sport is only turning that prop 4450rpm at 44mph. Its probably closer to 4800-4900. You'd want to prop it to run 4800-5000 anyways.

Ok, so next test will include some more jockeying of the ballast (putting it in the trunk), I will use the digital speedo instead of the dial, and I will hook up a temporary digital tach to verify operation. I probably will for go any additional video. I think the video taken so far demonstrates the water breaking point on the hull, and has established that I am reading the gauges correctly (HA!). IO got a get some time to fly down to DBQ, take Valant for his airplane ride and pick up his 1442 for testing... Dang work gets in the way!

Tim how would a ACME 2068 perform compared to the 422?
Would the extra cup (0.150) reduce WOT rpm's compared to the 470 with (0.105). Have you done any testing with this prop?

The reason I ask is that I damaged my 422 yesterday it may be repairable but I was thinking of ordering a new prop. I would have ordered a 1442 previously but you mentioned it would turn higher rpms just like the 470.

Details on how you chewed that prop! Boomer

kapla wrote: Details on how you chewed that prop! Boomer

We decided to go to a different dam that we had not been skiing on for a few years. It was a late decision on Sunday afternoon as the conditions were perfect and this dam is the closest but requires ideal conditions to get good water. It was down to about 80% capacity which we had no experience at either. I was actually skiing when the boat stopped, quickly realised what had happened when the water was just over knee deep as I dropped back into the water.

TRBenj wrote: What were your RPM's with the 422?

Tim, I was getting 4940 WOT on the 422. I had always wanted to try the 1442. I am leaning to ordering one and if it increases the RPM to much thinking of adding a bit of cup as it only has 0.090 standard.

The 422 may be repairable so I do not want to end up with 2 of them. Although I think that the 422 may be the best prop for our application. A fresh untouched 422 may even been better than my 422 that I have massaged a few times. I did have it repaired last year by a very reputable company before doing my prop testing.