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Do I need to go down in pitch?

Old 10-28-2019, 08:38 PM
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Originally Posted by Smoak352 View Post
Hydraulic.
Have you tried adjusting vertical position of the engine?... or engine trim at all?
Old 10-28-2019, 08:41 PM
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Smoak352 I agree with Jbetz...your not broken in yet . When my Suzuki broke -in I went from a 20 to a 23 with a greet hole shot and cruise range. The motor developed a noticeable increase in power as it broke in.
Old 10-28-2019, 09:18 PM
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Yes, you need to go down in pitch. A 19” or 20” pitch Revolution 4, Enertia ECO, PowerTech OS4 are all good candidates.

The 4.2 liter F300 has a 6000 RPM redline and a 1.75:1 gear ratio. You are a long way from that redline as is.
Old 10-28-2019, 09:44 PM
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Originally Posted by kdenap View Post
Smoak352 I agree with Jbetz...your not broken in yet . When my Suzuki broke -in I went from a 20 to a 23 with a greet hole shot and cruise range. The motor developed a noticeable increase in power as it broke in.
An OB motor with 9 hours should be about 5 or 6 hours past fully broken in.....or have permanently glazed cylinder walls, never perform to potential and/or make oil. The factory procedures are BS.
Old 10-29-2019, 04:56 AM
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Originally Posted by Smoak352 View Post
It is the prop used in the Yamaha Performance bulletin and they went 59mph at 5800 rpm so I thought it would be a good choice.
This is a brand new boat? If so Maverick has probably sold hundreds of them rigged with a 300 and should know what prop to sell with the boat. Its usually not the customers choice to make. I like to reach MAX rpms. Which should be higher then 6,000? The Yamaha may gain some rpms as it breaks in and up to 100 hours.
Old 10-29-2019, 06:26 AM
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Originally Posted by jfbetz View Post


A 3 blade 21 what? A 3 blade 19 what? There’s a bit more to it than blades and pitch. Different propeller models of similar pitch and blades can behave very differently.
With that engine, I had assumed he would stay with Yamaha SDS to avoid the Yamaha clank, so for three blade SDS, the SWS. BTW, after losing a second lower unit on my last boat, Yamaha insisted that I take off the Rev 4's that I was running. They claimed some interruption in cooling flow. It sounded fishy, but I did it and did not have any further problems.

I've owned 2 sets of F300's (5 total). I've never seen any noticeable change in RPM from day one through 1100 hours. Boats usually gain weight and props will get slower over time.

Last edited by scooperfl; 10-29-2019 at 06:32 AM.
Old 10-29-2019, 06:54 AM
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Originally Posted by alloyboy View Post
There is more to it that just being within a range.

The Owner's Manual goes on to say:

Yes, this is especially important with twins and trips where a user might be inclined to run 1/2, or 2/3.

5400rpm max is not optimal. On a bay boat, it will definitely affect holeshot, low speed performance, and efficiency if those are important to the user, but I do not think it will hurt the engine.

On my first set of F300's I insisted the dealer prop to 6000 and ended up with SWS 19's. Yamaha got involved, the area rep strongly recomended staying with the 21's for 5700, never saying why. A few months later I trolled for a week and it made a lot of oil. I was able to run it hard on the way back and it cleared up. I switched to the Rev 4's (great props for an offshore boat) and ended up at 5700, then had lower unit issues, sold them and went to 21 SWS.

In light of the engine's potential for making oil, propping to 6000 does not do this engine any favors. I would prop to 5700 with a "normal" load.

Old 10-29-2019, 07:39 AM
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Ok, after all of the input I just ordered a Powertech OFX4 in a 20 pitch. I will post the results in a few weeks.

Thanks for the input guys.
Old 10-29-2019, 07:54 AM
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Originally Posted by scooperfl View Post
In light of the engine's potential for making oil, propping to 6000 does not do this engine any favors. I would prop to 5700 with a "normal" load.
did you mis-type?? This is contrary so everything people have been saying about Yamahas in particular for the past few years. Over-propping (NOT reaching max rated RPM) IS what leads to engines making oil.....
Old 10-29-2019, 07:56 AM
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Break in that motor first, say 50 hrs. Then mess with props
Old 10-29-2019, 07:58 AM
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Originally Posted by scooperfl View Post
I switched to the Rev 4's (great props for an offshore boat) and ended up at 5700, then had lower unit issues, sold them and went to 21 SWS.

Others would likely know the why but Rev 4's and 4.2 Yams seem to be problematic combination.

Old 10-29-2019, 08:01 AM
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Originally Posted by Smoak352 View Post
Ok, after all of the input I just ordered a Powertech OFX4 in a 20 pitch. I will post the results in a few weeks.

Thanks for the input guys.
You shouldnt have to order anything. Are you working with maverick and your dealer? They know what that rig should have. Unless you dont agree with them? But it should still be free and included with the boat.
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Old 10-29-2019, 08:16 AM
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Originally Posted by HTJ View Post
Others would likely know the why but Rev 4's and 4.2 Yams seem to be problematic combination.
The problem related to the seals used in the lower unit; that problem was corrected circa 2013/2014. I think Yam switched back to the seals used on the 3.3L
Old 10-29-2019, 08:49 AM
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Originally Posted by barrell View Post
You shouldnt have to order anything. Are you working with maverick and your dealer? They know what that rig should have. Unless you dont agree with them? But it should still be free and included with the boat.
Correct path to follow. On my Cobia brand new from the factory the prop is supplied them. It was not getting me to the sweet spot. I had the dealer install the correct prop, didn’t cost me a dime. Unless you told Maverick you were supplying your own prop it shouldn’t cost anything. Even still, Grady White does not supply the prop, the dealer does. But it makes no difference. It’s all part of the rigging you pay for.
Old 10-29-2019, 08:59 AM
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Originally Posted by HTJ View Post
OP - Performance tests are done with 3 gallons of fuel, and two starving Ethiopian testers on board - you are over propped, have a too deeply mounted engine or some combination of both. Continuing to run it in an overpropped state may lead to oil making and increased fuel useage but will not fix it.
Hey, my best friends brothers uncles cousins is Ethiopian and he’s 250 and 6’ 2”. Regardless of your opinion the testing done is a baseline. On my new Cobia from the factory they had installed the wrong pitch prop. 5400 rpms tops. The Yamaha PB had the correct pitch. Had dealer install that prop and now motor runs up to 5900 rpms.
Old 10-29-2019, 09:59 AM
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Originally Posted by sclancy View Post
did you mis-type?? This is contrary so everything people have been saying about Yamahas in particular for the past few years. Over-propping (NOT reaching max rated RPM) IS what leads to engines making oil.....
IMO, the "it has to turn 6000rpm" idea is a bit of an anachronism. With carburetors and/or two strokes, it was no doubt critical (and most of those had a 500RPM rpm window). With high performance diesel engines, it is absolutely critical to be in the specified band. In a fairly conservative (maybe 300hp/260cu-in) modern engine with computerized fuel mapping, o2 and other sensors, etc., I do not believe it is necessary to be at the exact top of the band. Within the band, the engine will be fueled to keep AFR where it needs to be.

It is pretty well accepted that high cylinder pressures and high cylinder temps are what seats rings. Note that is cylinder temperatures, and not cooling water temperature which is more or less constant. Cylinder temps and pressures are dependent on load and rpm. So under-propping the boat (6000 with a usual load) would result in substantially lower cylinder temperatures and pressures, particularly at cruise speeds and that could adversely affect the ring seating process. The low load, low temp operation can also lead to carbon buildup. Of course that does not mean you can go overboard the other way either. Yamaha props boats to 5700RPM, which is the center of their guidance (upper half of the band) sited above. I do not believe this is arbitrary.

My first set of two F300's were propped to 6000 and perhaps babied a little, and they each made exactly the same amount of oil for the first 100 or so hours. My second set of three F300's, propped to 5700 (usual load), run a bit harder (this boat can just run faster more often) and WOT tested regularly, have been good from day one to 900 hours so far. Might be a coincidence, but I doubt it.

Last edited by scooperfl; 10-29-2019 at 11:14 AM.
Old 10-29-2019, 10:05 AM
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Originally Posted by barrell View Post
This is a brand new boat? If so Maverick has probably sold hundreds of them rigged with a 300 and should know what prop to sell with the boat. Its usually not the customers choice to make. I like to reach MAX rpms. Which should be higher then 6,000? The Yamaha may gain some rpms as it breaks in and up to 100 hours.
The propeller with the boat may be perfectly fine with the boat. As the boat is delivered.

Problem is that most new boats won't be staying new boats. Weight gets added. Boating is done in the high temperatures and humidity of summer time.

Time and time again here on THT and other similar sites we see where a new boat is over propped after it is outfitted and loaded for typical use. The propeller the boat came with will have approximately 2" pitch.

Oh, and most motors won't be mounted at the most efficient mounting height.
Old 10-29-2019, 10:07 AM
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Originally Posted by Jay Novo View Post

Correct path to follow. On my Cobia brand new from the factory the prop is supplied them. It was not getting me to the sweet spot. I had the dealer install the correct prop, didn’t cost me a dime. Unless you told Maverick you were supplying your own prop it shouldn’t cost anything. Even still, Grady White does not supply the prop, the dealer does. But it makes no difference. It’s all part of the rigging you pay for.
Maybe. Maybe not.

It depends upon what the contract/purchase order says.

I have never seen or heard of a contract/purchase order that mentions dealer will do whatever is necessary so that the customer gets maximum performance from a boat, motor and propeller.
Old 10-29-2019, 10:17 AM
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PM Ken @ prop gods if he doesn't poke in
Old 10-29-2019, 10:28 AM
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Originally Posted by alloyboy View Post
Maybe. Maybe not.

It depends upon what the contract/purchase order says.

I have never seen or heard of a contract/purchase order that mentions dealer will do whatever is necessary so that the customer gets maximum performance from a boat, motor and propeller.
Pretty much the same THT hog wash everyday. If the dealer you know or seen or heard of doesn’t want your boat to perform correctly you bought from the wrong dealer.

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