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  Best Prop - Planing at low speed in rough water

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Author Topic:   Best Prop - Planing at low speed in rough water
Smithsm posted 06-03-2009 08:41 AM ET (US)   Profile for Smithsm   Send Email to Smithsm  
We just splashed out New-to-us 1998 Outrage 20 with a 225 FICHT RAM '2000 engine and 17" aluminum omc prop.

The engine likes to run at 4100 RPM doing about 32 mph on calm water. When I try to follow a bigger boat home through rougher water the engine does not like trying to maintain plane at 25 mph - it just does not want to run in that RPM range (based on my interpretation of sound and the boats behavior) Perhaps this hull just does not want to plane at these lower speeds. It was 3/4 tank of gas and my lightweight wife and myself on board only.

I have purchased a 19" Mirageplus prop and will put it on when it arrives. I believe it will perform better than the 17" aluminum in terms of economy as measure by MPG - and speed - and it may or may not end up being our final prop. With 225+ HP on a 20' Outrage I have HP to spare.

One of the challenges of our boating environment are BOTH he waves and size of our bay. We boat on the Raritan bay in northern NJ/Southern NY. Due to its size and huge opening to the north atlantic it can get rougher than waters usually described as "bays". (a typical "bay boat" is too little boat for these waters) And it's size often means I have many miles to cover to get home in these conditions - especially at the end of a fishing day when the wind has been going for a while and the bay shows the effects. So the challenge both rough water AND miles of rough water.


Here is the point: When the water gets rough and I need to cover lots of miles to get home I want to run the boat on the SLOWEST POSSIBLE PLANE. Planing at 30-32 mph tends to send us airborne in moderate waves.

Based on my latest research perhaps a 18" pitch 4 blade prop will ulitmately give us performance similar to the 19" Mirageplus but ALLOW US TO MAINTAIN PLANE AT A LOWER SPEED - without sacrificing too much MPG (that also matters a lot to me).

Does this make sense to you guys ?
I am looking forward to your comments.

Peter posted 06-03-2009 10:37 AM ET (US)     Profile for Peter  Send Email to Peter     
In the past, I have equipped the Johnson 150 that pushes my 18 Outrage with a 15 1/2 x 17 inch pitch MiragePlus and found that it produced a terrible rough water ride. The propeller could not hold plane at a slow enough speed and as soon as any air was introduced it had a difficult time sheding it. I switched to a 14 1/2 x 19 inch pitch OMC SST. It performs almost exactly the same as the MiragePlus from an RPM to speed basis but the ride comfort is significantly better because the propeller doesn't lose traction sharply like the MiragePlus did.

The only way to truly know what propeller will work best is to try a bunch of them.

Tohsgib posted 06-03-2009 11:39 AM ET (US)     Profile for Tohsgib  Send Email to Tohsgib     
My 20' Hydra-Sports with 225 OMC would not like to run slower than 3500rpm and about 25mph. It sounded like the engine was seriously straining. It liked 3900-4k and about 31-33mph. I do however think a set of trim tabs would have cured that as I could dig them in and throttle up so the engine was happy but speed was slow. Secondly I notice this with most OMC 225's that they don't like it under 3500 where a Yamaha or Mercury would just pur at 3k and not complain. Weird.
Jeff posted 06-03-2009 12:13 PM ET (US)     Profile for Jeff  Send Email to Jeff     
Find a prop that works well for how you use the boat in all conditions. Then invest in a set of 9x9 or 9x12 Lenco trim tabs.
Smithsm posted 06-03-2009 02:49 PM ET (US)     Profile for Smithsm  Send Email to Smithsm     
Tohsgib

your writup pretty much describes my engine and boat combo so far.

I try my Mirageplus and see how it goes.

Everything is great on calm days - but this bay can get rough in a hurry and 25 mph is the speed I seek.

In all honesty, so far based on my limited experience with the 1998 Outrage 20 I would say that my 1988 Outrage 20 with twin OMC 60's handled the chop better. I ran at 4500 RPM at 25 mph and the more narrow hull took the chop much better at the slower speeds and more narrow dimensions.

but I really like other things about the newer outrage - so I will be on a quest to try different props

so far no one has commented on 4 blades vs 3.

any 4 blade comments out there ?

acseatsri posted 06-03-2009 06:12 PM ET (US)     Profile for acseatsri  Send Email to acseatsri     
My vote is Bennett M120 trim tabs. I had these on my 18 Outrage and they let me cruise at any speed without the bow in the air. I have Lenco 12 x 12's on my 22 Outrage now. If given the choice, I would go back to the Bennetts.
L H G posted 06-03-2009 06:27 PM ET (US)     Profile for L H G    
The best prop out there for maintaining plane at lower speed and RPM is a Mercury Revolution-4, followed by the Vensura. Since an Outrage 19/20 is a little small for the Rev-4, and since the OMC gearcase does not handle it well, I would go for the Vensura. You will like it. Mirage Plus for your app? Forget it.

Nick - it's not weird at all, just superior powerhead design.

John W posted 06-03-2009 06:28 PM ET (US)     Profile for John W  Send Email to John W     
As other have said, trim tabs will make the biggest difference. But to answer your question, a four bladed prop - in general - will allow for planing at slower speeds, it will pop on plane quicker, and it will handle better in rough water. You will give up some top end speed, and perhaps a very slight reduction in cruise speed efficiency.

If you have traditional push-pull type control cables, you will also see less RPM "drift" when running & you will have to adjust the throttle less in order to hold a particular rpm with a 4 blade prop as well (if you have electronic controls this won't be an issue regardless of the prop).

I'm sure some prop guru will post to say that certain 4 blade props do not perform as outlined above, but in general the above holds true. I can't help much with particular brand or pitch for your boat, though. Hopefully someone else can.

John

jimh posted 06-03-2009 11:01 PM ET (US)     Profile for jimh  Send Email to jimh     
I have used a Mercury MIRAGEplus propeller on my Evinrude 225-HP. I have published many comments about it, measured its speed and slip, and charted its boat speed. My notes show that the last time out with this propeller it did not seem to provide much of a bite in rough seas.

For a propeller to use in rough seas and for trying to maintain plane at lower speeds, I also suggest a four-blade propeller. BRP has a line of four-blade propellers called OFFSHORE. There is also a new line from BRP called the CYCLONE.

I have tested a CYCLONE four-blade propeller with an E-TEC 250 H.O. It produced very good fuel economy and was able to maintain the boat on plane at a lower speed than other propellers tested.

My published comments and test data appear in several articles:

http://continuouswave.com/whaler/reference/ETEC250HO.html
http://continuouswave.com/whaler/reference/propellerWDSingle.html
http://continuouswave.com/ubb/Forum4/HTML/004799.html

In total about 15 propellers have been tried on my boat. At the moment I own four of them.

Peter posted 06-04-2009 08:00 AM ET (US)     Profile for Peter  Send Email to Peter     
I should also add that about 5 years ago I used this same 15 1/2 x 17 Mirage Plus (as well as its counter rotating counterpart) off shore in a significant sea state on my 27 Whaler WD and the pair produced a similarly uncomfortable ride. Not long after that experience, I acquired a pair of Revolution 4 4-blade propellers for 27. (I also tested a bunch of others including the Offshore that Jim mentions). Ride difference between them is almost as distinct as night is from day. The 27 Whaler with the Rev 4 powers through waves whereas those same waves would almost stop the 27 Whaler in its tracks with the Mirage Plus propellers.
Calm water fuel economy is better with the Mirage Plus but rough water fuel economy is better with the Revolution 4 simply because it doesn't lose traction like the Mirage Plus does.
Tom W Clark posted 06-05-2009 10:27 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
Skip,

Propellers are not generic pieces of hardware that vary merely by diameter, pitch and the number of blades. In all cases you must consider the model of propeller used and the boat and motor on which it is used as well as how the motor is mounted to the boat.

I do not know what model and size of propeller will be best for maintaining minimum planing speed on a 1998 Outrage 20 with a 2000 Evinrude Ficht 225.

I do know from personal experience on my own different Whaler that the Mercury Revolution 4 works well on that boat, a Revenge 25 with twin 150 Mercurys, for that specific task.

I also know that the Mercury MIRAGEplus works fairly well for maintaining low planing speeds and yields better fuel economy and higher top speed than the Revolution 4, but this may not be the case on your boat.

I know as well, that the Mercury VenSura (Offshore) is a lousy prop on my boat and ventilates so easily that the motors cannot be trimmed out at all. It would be a very poor choice for maintaining minimum planing speed on my boat.

ASIDE: The Mercury VenSura (Offshore) is know to be a prop that has to be run fully submerged to avoid ventilation. It will not tolerate higher motor mounting heights as will the MIRAGEplus and Revolution 4. This may account for why it performed so poorly on my boat where the the MIRAGEplus is superb.


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