Jump to content

Welcome to TheMalibuCrew!

As a guest, you are welcome to poke around and view the majority of the content that we have to offer, but in order to post, search, contact members, and get full use out of the website you will need to Register for an Account. It's free and it's easy, so don't hesitate to join the TheMalibuCrew Family today!

Sign in to follow this  
martho

06 RLXi Prop questions

Recommended Posts

martho

I found several previous threads with the search function, however I didn't find the answer for which I was looking.

I was out today in the RLXi in 59 deg water. With just me, the boat would turn 5100 RPMs and would run 46.1mph. I have an ACME 515 which is 13 x 12. For those who believe the speedo, I was running 51.3mph but the GPS tells the real story at 46.1

If I go 13 x 12.625, how much more top end can I see? If I could gain 2mph and dump a few RPMs, that would be outstanding

Is there anyone running a 13x12.625 or 13x13 ACME on their 05/06 RLXi?

Share this post


Link to post
awilco
I found several previous threads with the search function, however I didn't find the answer for which I was looking.

I was out today in the RLXi in 59 deg water. With just me, the boat would turn 5100 RPMs and would run 46.1mph. I have an ACME 515 which is 13 x 12. For those who believe the speedo, I was running 51.3mph but the GPS tells the real story at 46.1

If I go 13 x 12.625, how much more top end can I see? If I could gain 2mph and dump a few RPMs, that would be outstanding

Is there anyone running a 13x12.625 or 13x13 ACME on their 05/06 RLXi?

Hi, I run a 1997 Response so I can't comment but I have an Acme #449 13x12.625 if you need it let me know. May trade for your 515?

Share this post


Link to post
VinRLX
If I go 13 x 12.625, how much more top end can I see? If I could gain 2mph and dump a few RPMs, that would be outstanding

Theoretically, 4900 RPM for 47.1-48 MPH. Be interested to see some real numbers from other folks with this set up. Obviously, you realize you'll be giving up some holeshot, yes?

Share this post


Link to post
mibarefooter

you could call ACME direct and they will probably be able to tell you. 888-661-2263

Share this post


Link to post
martho

Im sure ACME and OJ can give me their numbers. I am looking for real time reports, too.

I have dealt with OJ and ACME several times previously.

Share this post


Link to post
VinRLX

Mark, hopefully you'll get the real-water numbers you're looking for. I'll be interested to how they stack up against some theoretical numbers. . .

13x12 @ 5100 RPM = 46.1 MPH and demonstrates a 20% prop slip at WOT

Assuming the 20% slip is constant and guesstimating the effect of pitch change on RPM you might see:

13x12.625 @ 4900 RPM = 46.8 MPH

13x13 @ 4800 RPM = 47.3 MPH

Formula used is: Pitch x RPM ÷ 12 x 60 ÷ 5280 x .8 = MPH

Share this post


Link to post
martho

Hi Jack.

I think you are very close to what I am going to see. I'm not sure I am going to change props, however I am looking for other options.

My hole shot is fine and I would trade a touch of holeshot for a a bit of top end to foot.

I know I am going to end up putting all three props on the boat and testing as each engine is a touch different.

Share this post


Link to post
VinRLX

Cool, good luck with it. Do let us know the results. Inquiring minds want to know. :)

Share this post


Link to post
martho

Something I never really considered....

My rudder is loaded a bunch. Any thoughts as to how much drag / effect that has on the boat? I will change that the next time out and see if there is much difference.

Share this post


Link to post
VinRLX

I'm out on that one, haven't played with the rudder adjustment yet. Somebody else?

Share this post


Link to post
UWSkier

from a drag perspective, having your rudder loaded a bunch shouldn't make a real big difference I'd think. It's still going through the water straight.

Share this post


Link to post

Galaxytoad runs a ACME 13 x 13 on his boat and you can PM him for number but last year at TR his boat turned like 47mph WOT with the 13 x 13 and mine turned like 46.5 with the 13 x 12. Niether boat was rev limited and I think I was only seeing something like 4850RPMS and I can't recall what he was turning for RPMs. The speed figures were based on GPS readings. There was most definitely a holseshot difference between the boats but I didn't think his holeshot was slow.

Share this post


Link to post
Woodski

I disagree on the comment of rudder loading not increasing drag, it will. A loaded rudder has unequal lengths of rudder surface on either side. When the water flows over each side of the rudder and the lengths are not equal, it will cause shear which generates drag.

Share this post


Link to post
VinRLX

The newer rudders have an adjustable tab. Steering torque is increased or diminished by moving the tab.

Share this post


Link to post
multiplemalibufamily
I found several previous threads with the search function, however I didn't find the answer for which I was looking.

I was out today in the RLXi in 59 deg water. With just me, the boat would turn 5100 RPMs and would run 46.1mph. I have an ACME 515 which is 13 x 12. For those who believe the speedo, I was running 51.3mph but the GPS tells the real story at 46.1

If I go 13 x 12.625, how much more top end can I see? If I could gain 2mph and dump a few RPMs, that would be outstanding

Is there anyone running a 13x12.625 or 13x13 ACME on their 05/06 RLXi?

Yup! I am but with a bit of a twist. My prop has been locally repitched/reprofiled to provide a very slight cup at the last 3/8 inch or so of trailing blade area. At 8400 ft elev. This boat turns 5100 rpm at 48.7mph on radar. Awesome footin holeshot from a 340 Monsoon with high altittude tune up in chip. Props are the deal for the RLXI and the acme 13 x 12.625 was a great starting point to work from. At least for the hull prior to the 07 model. BTW our water is cold comparatively year round. This year I am going to experiment with a little less diameter and bit more cup at the trailing edge. Will let you know how it works out.

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...