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Author Topic:   1984 OUTRAGE 22; Mercury 150-HP FOURSTROKE Four-Cylinder 3.0-Liter
Richard Shears posted 04-21-2014 06:54 PM ET (US)   Profile for Richard Shears   Send Email to Richard Shears  
For my 1984 Boston Whaler OUTRAGE 22, [I] bought a new Mercury 150 FOURSTROKE (four-cylinder 3.0-liter) [i.e., not the Mercury 150-HP VERADO FOUR-CYLINDER 1.7-liter FourStroke]. [It is an] incredible engine and great performance. Then, two months ago [the propeller] developed severe [ventilation] at [an engine speed of] 3,200-RPM. If power [is increased] past that point and backed off, all runs fine. But if I gradually increase [engine] speed past the 3,200-RPM, [the propeller] never really grabs. The [engine speed] increased by 400-RPM and [boat] speed [went] down by 5 to 8-MPH.

First, the propeller was changed to 17 pitch [from unknown propeller and unknown pitch, and the results were] worse.

Four-blade 15-pitch [gave] worse [results, and the propeller was changed] back to 15 pitch.

The boat was pulled to check for hull abnormalities: nothing--all good, no change in any transducers or pumps. Lowered the engine [mounting height, and the results were] even worse. I put the engine back to original position. I mounted a Dol-Fin [and there was] no difference.

I have ordered [an ENERTIA propeller] but feel nothing will change, as everything was fine for a year. This has me, my friends, and our Mercury mechanic stumped! Any insight will be more than appreciated.

Rich S.

[Editor's Note: See the follow-up article to find the actual cause of the propeller ventilation problem with the Mercury 150 FOURSTROKE.--jimh]

Teak Oil posted 04-21-2014 08:48 PM ET (US)     Profile for Teak Oil  Send Email to Teak Oil     
Sounds like hull fouling or barnacle growth, but you said you checked the hull.

Changing props rules out prop damage or a spun hub.

Hope its not a issue with the lower unit, slipping when its under the heaviest load.

You can try lowering the engine a set of holes, but I am running mine up as high as it can go.

You should try a quality prop with large blades, like a Mercury Mirage or Rev 4

Tom W Clark posted 04-21-2014 09:19 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
A Mercury 150 FourStroke mounted on a 1984 Outrage 22 should be mounted at least two holes up, maybe three, depending on the propeller used.

You mention several propellers were tried but you do not say what they were apart from the pitch. It is the one that *used* to work well I am curious about.

What you describe sounds more like ventilation than cavitation.

With all the different propellers tried, was the same hub kit used?

How are you trimming the motor?

Richard Shears posted 04-21-2014 09:28 PM ET (US)     Profile for Richard Shears  Send Email to Richard Shears     
The original prop was was a 15 pitch. We are back to that one [still unidentified propeller] with the ENERTIA or MIRAGE on order to try. And the same hub was not used. And I meant ventilation, not cavitation. The problem is that [the original propeller and engine mounting height] ran fine for a year. Thanks Teak Oil and Tom.
Tom W Clark posted 04-22-2014 10:14 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
A 15" what?
jimh posted 04-22-2014 10:16 AM ET (US)     Profile for jimh  Send Email to jimh     
Since the onset of the problem with the propeller ventilation, it appears that no remedy has been provided by changing propellers or by changing engine mounting height. On that basis it seems reasonable to conclude that the cause of the ventilation is not from a defect in the propeller or from the engine mounting height being incorrect.

It is assumed there has been no change in the engine. The gear case and all portions of the engine that are immersed are assumed to remain unchanged.

This leaves the boat as the only element that may have changed. I suggest temporarily removing any SONAR transducers or other devices mounted on the transom that could be disrupting the water flow. Also, check the boat hull bottom for any possible changes. Check the hull close to the transom to see if the hull has been warped or changed in any way. Perhaps the new engine has, either from additional weight or additional power, caused some deformation to occur in the hull.

jimh posted 04-22-2014 10:19 AM ET (US)     Profile for jimh  Send Email to jimh     
A propeller that ventilates will often lose all grip. The symptoms you describe sound more like a propeller with a loose or spun hub. However, you seem to indicate you have replaced the Mercury FLO-TORQ hub, or used a different hub with different propellers. Please give more information about the propeller and hub.
Richard Shears posted 04-22-2014 02:42 PM ET (US)     Profile for Richard Shears  Send Email to Richard Shears     
I am and have been using a three-blade Mercury 15-pitch aluminum propeller. The new, recommended, cupped, Mercury, stainless, 15-pitch is on order. Not sure of the name.

When we changed propellerss, we used new hubs.

The hull looked fine when the boat was pulled. No abnormalities seen. It was cleaned and painted in October. There were three of us checking it, but we could have missed something--always that possibility.

[The propeller] loses some grip at 3,200-RPM, right as [the boat] breaks to a plane. Once I throttle to 5,000-RPM. I can hear the propeller re-grip the water. I then can throttle back to 4,200-RPM, and cruise comfortably at around 22 to 24-nautical miles per hour. If conditions are bumpy, and the throttle is backed to the 3,200-RPM point, there is partial ventilating effect, again. There does not seem to be an problem in a following sea during flat conditions. The engine RPM and boat speed are great. Into a head sea in sloppy conditions is a different story, as often I am back and forth from 3,000 to 4,000-RPM.

My fishing partner, who has the same engine (but on a 21-foot Boston Whaler), and who is also very good at diagnosing problems, hung over the stern during the ventilating period and saw no problem. The propeller was in clean water.

Again, this ventilating at 3,200-RPM is not a 100-percent loss of water grip, but more like 30 to 50-percent.

We are all stumped at this point. The new propeller will be in next week. Again, all input is appreciated. Super aggravating problem!

Tom W Clark posted 04-22-2014 04:17 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Well, if you were using an aluminum propeller, that was a big part of the problem. Aluminum propellers do not offer much grip and can easily be overpowered.

What was your best top speed? Do you know what RPM it was seen at?

Tom W Clark posted 04-22-2014 04:23 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
I should add that because aluminum propeller blades are not very strong, it is easy to bend them. One blade, bent a little to throw it out of track with the other two blades, might look normal to the untrained eye but throw the performance off completely.

If you have a 15" x 15" Mercury Enertia coming, try it out. Be sure the PVS vent holes are plugged solid.

Also, be sure the motor is mounted two or three holes up and lose the Doel-Fin.

Richard Shears posted 04-22-2014 04:42 PM ET (US)     Profile for Richard Shears  Send Email to Richard Shears     
Thanks, Tom. I do think it is the Enertia that is coming. I think our top speed was 28 to 30 nautical miles per hour at 5,500-RPM, when we are up past the slip.The engine is mounted on the third hole [This does not really describe the position. Please describe engine mounting height in units of 0.75-inch or "hole" and measure from the lowest possible position. Perhaps you mean the engine is mounted two-holes up from the lowest. Let us know--jimh].

I was wondering about the propeller being bent from crab rope tangles. That is why we went to the new propeller. But had the same problem on the first trial run. Fingers crossed on the new propeller.

acseatsri posted 04-22-2014 07:18 PM ET (US)     Profile for acseatsri  Send Email to acseatsri     
Is the trim tab still present? I had one fall off once and it acted differently than when it was still there.
jimh posted 04-23-2014 07:50 AM ET (US)     Profile for jimh  Send Email to jimh     
Have you checked the propeller shaft to see it there is any bend? Maybe one of the crab trap rope entanglements pulled the propeller shaft out of true straight. Some wobble in the propeller shaft could explain problems at higher propeller shaft speeds.
Richard Shears posted 04-23-2014 09:21 AM ET (US)     Profile for Richard Shears  Send Email to Richard Shears     
Shaft looked ok to the naked eye. But that thought crossed my mind.
Conchyjodyoos posted 05-01-2014 08:33 AM ET (US)     Profile for Conchyjodyoos  Send Email to Conchyjodyoos     
Hello Richard, if it helps I have the exact same set up and I'm running a 15P mirage plus, solid pvs plugs, mounted with the engine cavitation plate nearly even with the hull bottom. Runs perfect, 34-nautical-miles-per-hour at 5,500-RPM. I know most here would say raise the engine, but it runs so nice I'm afraid to change it. I reached my first year of ownership (four-stroke Mercury 150) and, logging just over 200-hours, I can say this engine has far exceeded my expectations.
Richard Shears posted 05-02-2014 08:41 PM ET (US)     Profile for Richard Shears  Send Email to Richard Shears     
The new prop arrives next week. I have to say I am not all that optimistic in that the engine ran beautiful not long ago.
But I have had a lot of people raising concern about aluminum prop flex.Engine is mounted with cavitation right even with the hull..maybe a hair higher. Will post the results. Thanks for the input!
fishinchips posted 05-11-2014 09:56 AM ET (US)     Profile for fishinchips  Send Email to fishinchips     
If new prop don't work, I would bring the boat andmotor to the shop and have them make sure the motor is running okay.

I know that the VERADO and the 115 EFI are based on the same design. I do know some folks with these motors have had problems with pencil coils failing. If a pencil coil goes OUT, you will be able to start. You're able to run, but cannot get onto plane. The engine won't reach top RPM. However, the engine may reach 3000-RPM and may temporary reach higher RPM, but falls off quickly.

I am not familar with the 150-HP new version; better see if you have pencil coils. Good Luck and I hope you find the problem.


jimh posted 05-16-2014 09:58 AM ET (US)     Profile for jimh  Send Email to jimh     
I believe that the 150-HP FOURSTROKE (3.0-liter four-cylinder) and the 150-HP FourStroke VERADO FOUR-CYLINDER (1.7-liter) do not have much in common in terms of the engine design. Whether or not the spark coils in the 3.0-liter engine are provided on the top of the spark plugs, what is commonly called coil-on-plug and is what I believe you mean when you refer to "pencil coils" as used on the 1.7-liter engine, I don't see how a malfunction of a spark coil might cause the propeller to ventilate. Generally the loss of one cylinder in a multi-cylinder engine like the Mercury 150-HP FOURSTROKE 3.0-Liter will cause a reduction in power output, but I doubt that would be manifested in the ventilation of the propeller.

Ventilation of the propeller occurs when air above the surface of the water is sucked down into the water and envelops the propeller blades. I do not believe that failure of a spark coil could be the actual cause of this phenomenon.

Richard Shears posted 05-16-2014 03:26 PM ET (US)     Profile for Richard Shears  Send Email to Richard Shears     
Well we changed the aluminum prop to the 15 Enertia. What a difference. Although I still get a some cavitation or ventilation when I take off, it disappears in a few seconds. Still not quite sure what causes it but compared to when I was dealing with, the new Enertia is a 90% improvement. 25 knots at 4300 RPM when I was at 5000 RPM @ 20 knots. Thanks to everyone on the site for their input. Most helpful and appreciated!!!
Tom W Clark posted 05-16-2014 04:29 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Richard -- I am glad you have solved your problem simply by installing a stainless steel propeller.

I suspect your old aluminum prop was ventilating because it was sightly damaged; it is easy to bend an aluminum blade, throw the geometry off and still have it look normal to the untrained eye.

Richard Shears posted 05-16-2014 07:53 PM ET (US)     Profile for Richard Shears  Send Email to Richard Shears     
Actually the aluminum prop was new...right out of the box!
jimh posted 05-17-2014 02:04 AM ET (US)     Profile for jimh  Send Email to jimh     
I like Tom's theory, which, if I may, I express as follows: sometime during the operation of the boat with the aluminum propeller, something happened, perhaps one of those incidents with fouling on a crab pot, that caused the aluminum propeller to become deformed very slightly, but the deformation was enough to affect the operation of the propeller and caused the ventilation.

It is quite interesting to know you got the ENERTIA propeller and the ventilation has been solved.

sosmerc posted 05-18-2014 11:41 PM ET (US)     Profile for sosmerc  Send Email to sosmerc     
I have seen numerous cases where the shipping pin (like a tilt pin, only steel, not stainless) was not removed by the installer. This would limit the available negative trim which definitely can affect ventilation upon initial efforts to plane out. The pin should be removed. It's purpose was to keep the engine upright in the shipping crate. Can't remember if the new 150 EFI FourStroke ever had one, but worth a look.
The Enertia should be able to run pretty high without ventilation. Are you PVS plugs solid, or do they have holes in them? You can purchase or drill holes of different sizes to fine tune the amount of initial slippage to aid in acceleration. But it sounds like you are already getting some slippage perhaps from not being fully trimmed "IN" for takeoff.

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