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Bringing down the RPM's on an F22 for surfing


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#1 Jeffsullj

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Posted 27 February 2018 - 03:12 PM

Hey you fine forum folks,
 
60 hours in on the 2018 F22 and surf tuning mode fully engaged.  :)
 
RPM's are hovering around 4000 (and sometimes more) when fully weighted for surfing... (internal full + standard 800lb bags on top) especially with a couple of folks or when I try to steepen the wave with an additional 500lb bag in front of the rear bench. Engine works hard, smoke, etc...  Pic of my buddy yesterday shows the messy wave I've got on the goofy side.  He prefers the cav plate all the way up for a steeper ride...  That'll be another post -- but I'm going to work on that more with weight movement/additions after I solve the RPM issue.
 
I've read in other posts about swapping props for torque/bringing down RPM's at the expense of top end.
 
Explained this to the local dealer while they were doing warranty work on the sound system and asked them to change out the prop. 
 
They came back with something along the lines of an alternate prop will cause excess wear on the underside of the boat due to pressure from water/bubbles?!?  They had a call into MB, but never heard back.
 
So... any idea what prop or pitch/specs I should specifically ask for? 
 
Thanks in advance!

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#2 The Donfather

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Posted 27 February 2018 - 09:45 PM

The smoke in the pix is normal when running without a surf pipe. The dealer was basically looking at a larger diameter prop. Yes if you get the prop to close to the gelcoat it will cause problems. Call acme prop and talk to them. They will help you out.
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#3 sand2snow

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Posted 27 February 2018 - 10:43 PM

That's steam from the 160 degree water coming out of the engine and hitting the cold lake water. What prop do you currently have on it? Do you have the 15 X 14.25 or the 15 X 12? 

 

Let me look tomorrow but you should be able to go with a 15.5 X 15.5. A little bigger prop with more pitch to lower your RPM's


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#4 mxvet

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Posted 28 February 2018 - 09:11 AM

If you are running around 4000 RPM, take your current prop to a local prop shop and have them add .025-.050 cup. that should drop you to 3700ish I have done this and keep my rpms at 3500-3800@11.2mph most days. IMO, at 4000 the motor starts to scream. It's a fine line however between low RPM and the ability to push 11+mph w/full ballast

 

Acme can sure help and they are the ones that recommended I take to local shop. 


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#5 Jeffsullj

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Posted 28 February 2018 - 09:38 AM

Thank you!  Excellent suggestions.  I'm checking with the dealer to see what I have on there now... May have to make a trip and take a look at it. (I keep it dry docked about 30 minutes away on the lake and rarely see it out of water. )  

 

Once I get that info I'll give acme a shout.  There is a local prop shop that carries acme locally -- http://www.nettleprops.com/ 



#6 mxvet

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Posted 28 February 2018 - 09:41 AM

Thank you!  Excellent suggestions.  I'm checking with the dealer to see what I have on there now... May have to make a trip and take a look at it. (I keep it dry docked about 30 minutes away on the lake and rarely see it out of water. )  

 

Once I get that info I'll give acme a shout.  There is a local prop shop that carries acme locally -- http://www.nettleprops.com/ 

 

Oh well you are set,, nettle is one of the best. 


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#7 Mgigs7

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Posted 28 February 2018 - 10:16 AM

Put that cave plate down a little to clean up the wave. Take weight out of the front if you want it shorter and steeper, Which nobody ever says BTW the shorter part. What’s your speed? That will change the wave as well.


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#8 Jeffsullj

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Posted 28 February 2018 - 10:43 AM

Dealer heard back from a MB tester today -- this is what he said:   He has found that adding the new surf pipe pulls the nose down and reduces noise.  He was impressed with the change that made when he started testing surf pipes.   Also stated that pipe and lead in the front might be just what your looking for.  Changing props he recommended a 2277 (15x15.75), standard is a 2247 (15x14.25).

 

I'll need to give that surf pipe some thought...  gotta find out how much $$... does it really drag that much on the boat to pull the nose down? 

 

As for speed... guy in the photo prefers 11.2 mph for goofy... I keep it at 10.8 for me (regular side) and dump a little weight (about half the 800lb bag) for slight biasing when we're not transitioning.  I run the cav 1/4 on regular and had been doing 3/4 on goofy - but my goofy friend doesn't like the wave to get flattened out by the cav and would rather surf it messy.   

 

Either way I'm going to work on the wave quite a bit over the next several weeks...  Maybe even get crazy and do a spreadsheet! :) I've got fat sacs/pumps from my old boat and can experiment moving things around until I find what I'm looking for consistently.  Then I'll bring on lead bags and be done with it.  #hopefully


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#9 mxvet

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Posted 28 February 2018 - 02:09 PM

Dealer heard back from a MB tester today -- this is what he said:   He has found that adding the new surf pipe pulls the nose down and reduces noise.  He was impressed with the change that made when he started testing surf pipes.   Also stated that pipe and lead in the front might be just what your looking for.  Changing props he recommended a 2277 (15x15.75), standard is a 2247 (15x14.25).

 

I'll need to give that surf pipe some thought...  gotta find out how much $$... does it really drag that much on the boat to pull the nose down? 

 

As for speed... guy in the photo prefers 11.2 mph for goofy... I keep it at 10.8 for me (regular side) and dump a little weight (about half the 800lb bag) for slight biasing when we're not transitioning.  I run the cav 1/4 on regular and had been doing 3/4 on goofy - but my goofy friend doesn't like the wave to get flattened out by the cav and would rather surf it messy.   

 

Either way I'm going to work on the wave quite a bit over the next several weeks...  Maybe even get crazy and do a spreadsheet! :) I've got fat sacs/pumps from my old boat and can experiment moving things around until I find what I'm looking for consistently.  Then I'll bring on lead bags and be done with it.  #hopefully

 

Nose weight will bring down the RPMs for sure, but I'm not sure what it will do to the wake on that boat. I like the surf pipe on the '18 MB I was on, I have FAE on mine though and its worth the $500-$600. You can probably get the surf pipe from your dealer around the same cost. Not sure about it pulling the boat down though.

 

If you buy a prop from nettle, you can exchange it until you find the right one i believe...


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#10 Tbag

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Posted 28 February 2018 - 04:19 PM

If these boats can fit a 15.5” diameter prop, the 2849 might be a great option. It looks like there is clearance for another 1/4”

Brian - interested to hear what MB has to say about the slightly larger diameter.

#11 OrangeTJ

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Posted 01 March 2018 - 06:21 PM

I have a 16 F22. Original prop was a 2249. I switched props to a 2279 and dropped several hundred rpm when surfing. Too speed increases from about 35 - 40. I am finding my best waves with the following - internal full, rear PNP about 600 per side, total of about 600 in the bow between lead and a bow bag. Speed 11.6 - 12 mph. 0-25% cav plate.
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#12 OrangeTJ

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Posted 01 March 2018 - 06:23 PM

Caveat - I am at 400 feet. This prop has been good with my setup upnto about 3500 feet. Just a bit short on pull up at Lake Tahoe when loaded up with ballast, but no problem cruising full or passengers or wakeboarding with just hard tanks full up there.

#13 Jeffsullj

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Posted 02 March 2018 - 07:11 AM

Thanks for all the advice...  really helped me narrow down conversations with the dealer, nettles, and the marina mechanic.  I also contacted ACME per @Donfather and @mxvet suggestions.  ACME is actually suggesting pitch in the opposite direction of what I was thinking with the 2277, but w/ a larger cup-size in line w/ what @mxvet said. 

 

Going to run some various load tests today to see if the prop is slipping under heavy load like they suspect.  

 

My current plan is to go with whatever prop acme recommends from Nettles and then will add the surf pipe, which the dealer is quoting a little over $800 shipped/installed.



#14 OrangeTJ

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Posted 02 March 2018 - 08:25 AM

2277 will work well, too. I borrowed one from a friend and tried it on my boat last summer. Very similar to my 2279 but with just a touch lower rpm and another mph higher top speed.

#15 OrangeTJ

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Posted 06 March 2018 - 12:22 PM

Just reread your last post. What diameter, pitch and cup are they recommending?

#16 Jeffsullj

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Posted 06 March 2018 - 01:05 PM

I don't have the details as the plans changed-- it was on a phone call last week with Todd from ACME while I was out and about.  He was going to send me the specs after I ran a few tests to see if the prop was slipping. 

 

I ran the tests and even recorded video.  Sent it his way and his response was somewhat incredulous and asked if I was sure I was currently running the 2247 (which I am.)  He then said "I’m a little hesitant, but go ahead and try the 2277 and let me know how it works."

 
Tests he had me run:
Surfing either side at 10.8 or 11.2 mph the boat ran at 3900 RPM fully loaded with 4000 lbs + 3 people
Wakeboarding at 20 mph the boat ran at 3900 RPM with 3000 lbs + 3 people. 
 
I've got the prop coming tomorrow (3/7) and hope to test it out later this week.  Will update the forum!

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#17 Jeffsullj

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Posted 11 March 2018 - 08:22 AM

Saga continues...  bought a 2277 and finally got to test on the lake yesterday.  RPM's only slightly down -- 3800, but the prop appeared to be slipping under load.  It didn't help that Lake Travis was fairly choppy yesterday --Mid 80's and sunny brings every boat owner within 1000 miles out.  I even saw another MB on the lake!   (fairly rare sighting in these parts.)

 

Chop slipping fun aside, RPM's are not down enough to make a difference.  

 

Going back to ACME to see what they recommend next.  May do the cup size increase on the 2247.  



#18 Jeffsullj

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Posted 12 March 2018 - 06:13 PM

Tested again today and it ran fine in good water... No slipping during surfing with tanks and bags completely full. Wakeboard speeds with full internal tanks ran fine too. RPMs were down to 3600...

So... After all that, RPMs not down enough to pay for the prop anytime soon in gas savings, but not a total wasted effort. Maybe I'll try the surf pipe next.



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#19 Bosshog

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Posted 12 March 2018 - 07:06 PM

More cup will bring down rpm with that prop. 150 cup maybe 180 cup

#20 mxvet

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Posted 13 March 2018 - 07:46 AM

Tested again today and it ran fine in good water... No slipping during surfing with tanks and bags completely full. Wakeboard speeds with full internal tanks ran fine too. RPMs were down to 3600...

So... After all that, RPMs not down enough to pay for the prop anytime soon in gas savings, but not a total wasted effort. Maybe I'll try the surf pipe next.



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RPM 3600 -- surfing or wakeboard? 


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