CNC Prop?

[Lake Ape]

Hey All,
I don't know much about props but I just got this one from ACME Marine and can't believe that the thing is Billet and was done a CNC machining center. I checked it with a mic and it's within thousands all around, damn near perfect! Are all the new props being made this way?
http://www2.***boat.com/image_center/data/520/2219Picture_016.jpg
http://www2.***boat.com/image_center/data/520/2219Picture_019.jpg

[Floored]

only ones I've seen were all for ski-wakeboard style boats, not for i/o or ob's.

[Tom Brown]

I would assume most production props are cast first and then CNC machined. :confused:

[SummitKarl]

Hey All,
I don't know much about props but I just got this one from ACME Marine and can't believe that the thing is Billet and was done a CNC machining center. I checked it with a mic and it's within thousands all around, damn near perfect! Are all the new props being made this way?
http://www2.***boat.com/image_center/data/520/2219Picture_016.jpg
http://www2.***boat.com/image_center/data/520/2219Picture_019.jpg
it's CNC machined alright, and a finish pass was done with a ball nose end mill and has yet to see the buffing wheel, me thinks they missed the finial process. fairly certian it will cavitate as it is.

[superdave013]

That looks like a nibral mid engine ski boat prop. Looks good man.
Ron Gross Racing is making them for flatbottom drag boats. I hear they work really well. Also heard it takes 16 hours to machine due to the material. So you could imagin how much they cost. :2purples:

[superdave013]

it's CNC machined alright, and a finish pass was done with a ball nose end mill and has yet to see the buffing wheel, me thinks they missed the finial process. fairly certian it will cavitate as it is.
Gross's props look like that too. You can feel the tool marks. They must work well because the NJBA Ski Flatbottom class record was set with one. 7.56 second et is not to shappy for the ski boat class. lol

[Havasu Hangin']

I would assume most production props are cast first and then CNC machined. :confused:
Most props have the ears welded on.

[SUICYCOLE DIMARCO]

i have a grose billet flat bottom prop on my runnerbottom and it works great...i find myself bringing it in the house and setting it on the coffee table although :D

[SummitKarl]

Gross's props look like that too. You can feel the tool marks. They must work well because the NJBA Ski Flatbottom class record was set with one. 7.56 second et is not to shappy for the ski boat class. lol
there might be something to that, kinda like a stepped hull reduces drag, but I built (machined) custom jetski motors and impellers, for years and it was all about thin and "smooth". BACK IN THE DAY!!!!!!!, all I see looking at that prop is cavatation potential. but the machine work sure looks nice!!

[Lake Ape]

I will let you all know how it works tomorrow if I can find a lake to get on to. Bartlett will most likely be closed so I am looking at either canyon or maybe pleasant. The prop was made by ACME Marine and the finish is intended to be that way. Supposedly they kick everything elses butt. MB Sports now runs them as there stock prop.
ACME MARINE (http://www.acmemarine.com/)

[Lake Ape]

I went out and tested the new prop this weekend. I originally had a 13 x 13 four blabe OJ prop on the boat and the top speed was 53 MPH at 4800 RPMS. I switched to a nibral 13 x 11.5 three blade prop and the hole shot was way, way better and the top end went up to 57 MPH (on GPS). So I would say that the the prop performed excellent, however I was on much rougher water at Lake Pleasant (I usually go to Bartlett where it's almost always flat). The strange part is that my mid-range has gone to hell, it feels mushy and the RPMS are up about 500 across the board. Could the prop be slipping in the mid-ranges but not at the top end? This doesn't sound right to me, what about to you all?
Thanks,
Lake Ape!

[SummitKarl]

I went out and tested the new prop this weekend. I originally had a 13 x 13 four blabe OJ prop on the boat and the top speed was 53 MPH at 4800 RPMS. I switched to a nibral 13 x 11.5 three blade prop and the hole shot was way, way better and the top end went up to 57 MPH (on GPS). So I would say that the the prop performed excellent, however I was on much rougher water at Lake Pleasant (I usually go to Bartlett where it's almost always flat). The strange part is that my mid-range has gone to hell, it feels mushy and the RPMS are up about 500 across the board. Could the prop be slipping in the mid-ranges but not at the top end? This doesn't sound right to me, what about to you all?
Thanks,
Lake Ape!
you gained top end as well as bottom end? the two usally don't happen togeather it's one or the other, you dropped the pitch considerably, so it should rocket out of the hole, and start to die off, what was engine RPM at (57mph gps) it should have been about 5400, if your motor turns that fast!!
maybe you went to far down on the pitch, thats a HUGE!!!!!!!!!!jump in pitch you made 1.5ft per rotation, you probally just are not in the motors power band any more

[Lake Ape]

The motor is a GM 400 Fast Burn Crate Engine. I just put the motor in about three weeks ago. It came out of a modified class stock car, the rules no longer allow it so out it came and replaced the 305 that originally came in the boat.
http://www.sallee-chevrolet.com/ChevySmallBlockV8s/images/88958604.gif
At 57 MPH the tach reads 5300 RPMS.

[SummitKarl]

The motor is a GM 400 Fast Burn Crate Engine. I just put the motor in about three weeks ago. It came out of a modified class stock car, the rules no longer allow it so out it came and replaced the 305 that originally came in the boat.
http://www.sallee-chevrolet.com/ChevySmallBlockV8s/images/88958604.gif
At 57 MPH the tach reads 5300 RPMS.
so you switched motors and prop at roughly the same time? by the chart you up'd your torque ALOT!!!!!!!! from what was there, I would have gone the other way and gone to a 13 x 14 and use the AWSOME torque curve on your motor, I can just hear you motor :cry: (more pitch please!!!)

[Lake Ape]

The boat is relatively new to me and you should know that its a tourny. ski boat. MB Sports 190 Plus. I just did what the prop guy at ACME told me to do, I don't really know anything about boats or props. So I should go to a 13 x 14 Nibril 3 blade? What will that give me? The boat is mostly used for wakeboarding, skiing, tubing and just plain old cruising. I do really like the fact that I can now blow by all the other specific ski/wakeboard boats out there.... Really the only reason I replaced the prop was because the old one needed repair and I didn't want to miss a weekend on the lake. I have 30 days to exchange props again if I want as long as it isn't dinged up.

[Lake Ape]

So should I go the other way?

[SUICYCOLE DIMARCO]

i noticed the billet dont flex as much as the welded ones.....keeps the times consistent.. :smile:

[SummitKarl]

So should I go the other way?
hey if they are giving you 30 days, take it!!!!!!!! Dial your boat in , keep exchanging it till you get the one that works best, you may find youself right back where you started, but I would at least try something like a 13 x 14. and see what it gets you, a 19' boat with a 400hp motor should be at least 65mph, go for it try the 13 x14, if you don't like it, the 13 x 13 will still be there for you

[Lake Ape]

hey if they are giving you 30 days, take it!!!!!!!! Dial your boat in , keep exchanging it till you get the one that works best, you may find youself right back where you started, but I would at least try something like a 13 x 14. and see what it gets you, a 19' boat with a 400hp motor should be at least 65mph, go for it try the 13 x14, if you don't like it, the 13 x 13 will still be there for you
It doesn't really matter but the boat is actually 20'3", I think they stretched and just didn't change the name. Here's the stock specs:
SPECIFICATIONS
MODEL 190 Plus
LENGTH 20'3"
WIDTH 92"
WEIGHT 2,400 lbs.
DRAFT 21"
PROP 13 x 12 Acme
BASE ENGINE PCM HO 5.0, 275 HP
FUEL CAPACITY 30 U.S. gallons
PRIMARY USE Competition slalom skiing
ADDITIONAL USES Recreational slalom and wakeboarding

[Jordy]

a 19' boat with a 400hp motor should be at least 65mph,
You're also talking about a competition style ski boat with lots of hook (typically), no cav plates and a drive system that is fixed to drive the bow of the boat into the water at higher speeds. That's why most of them you see out there don't run much over 50. ;)

[Lake Ape]

You're also talking about a competition style ski boat with lots of hook (typically), no cav plates and a drive system that is fixed to drive the bow of the boat into the water at higher speeds. That's why most of them you see out there don't run much over 50. ;)
Yup, I'm not exactly looking for a ton of speed, but it's nice to have. The only reason that particular engine went into the boat is because the previous owner owed me some money and I figured that was the only way I was ever gonna see any of it. It had a total of two races and some test time on it when I got it. The class rules changed and he could no longer use the motor also. As far as hook goes the boat has very, very little when check with a 4 ft. straight edge. Mike Brendal claims that his boats all have very little due to the fact the he leaves them in the mold for so long. He says he's only going to build about 300 boats this year max and really wants the numbers to be in the mid 200's. He says he can do this by making a nicer boat and charging more....