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I need a new propeller for my 1990 18' Outrage with a 2014 150 HP Mercury Fourstroke engine. My current propeller is a Stiletto Advantage 14 1/4" x 19" P/N E600319 three blade polished stainless. You can find a performance report on it here:

http://www.whalercentral.com/forum/vi...rowstart=0

That prop performs excellent for 95% of my use, but a couple times of year, I find myself in predictably larger expected sea states and experience unacceptable levels of ventilation, or lack of "hook up", in more extreme conditions. Most recently, crossing Death's Door while returning to Fish Creek in Door County WI from Washington Island off the tip, heavy rollers were the last straw. I could not keep the prop connected to maintain a slow plane speed of 16-18 MPH to prevent launching off each wave. I kept falling off plane, while maintaining RPM, and would have to back off the throttle, settle the boat and re-engage the propeller to run again.

Frustrating, even possibly dangerous, my young boys and wife enjoyed the roller coaster ride while I battled speed, throttle and 6-8' rollers with regular giants while quietly guessing the miles remaining. Remarkably, when we made it to Gills Rock where I met my wife and a boy with the truck earlier in the day heading north, I asked her to go and retrieve the trailer so we could tow it down the peninsula, rather than running it the rest of the way solo. I fished for smallmouth in Hedgehog Harbor and had a beer while I waited, killed 'em too...

I run the boat in Lake Michigan, Lake Superior, Lake Winnebago, Lake of the Woods and then various other inland lakes, some occasional salt. Its regular trips to the first two where the problem has arisen.

The motor is mounted 3 holes up, that is, in the 4th of 5 holes total. Its high, and I don't want to lower it. The Stiletto I have on it now is a speed propeller for lack of a better term; high top end and high cruising speed at 4000 RPM sweet spot and 35 MPH. I'm willing to sacrifice speed for better grip.

The boat can porpoise at some RPM and trim combinations, I can always trim out of it, but perhaps the Stiletto is creating some bow lift. With the added weight of the Fourstroke, I think some stern lift may be a possible improvement, perhaps even lowering minimum planing speed.

My goal is a prop with more bite, despite the high outboard mounting position. I'd like some suggestions. Physics say the additional blade area of a 4 blade prop would be beneficial, and I like the idea in concept. Of course, every prop model / brand performs differently. Perhaps someone else running this rig has a recommendation.

Patrick
Milwaukee, WI

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P -

In checking the member recommended prop sheet, the prop you have is one of the two recommended for that hull/engine combination.

If you are willing to sacrifice speed for grip why not consider going down a hole? You will only loose ~125-200 rpm's at WOT. The benefits will be less ventilation (prop is sucking air).

In doing a search I did find this comment from a member that may be helpful. While it was a few years ago, he has the same model and issue you have.



If you are willing to spend the $, - -

Consider Larry's prop suggestion here - http://www.whalercentral.com/forum/vi...ost_138580

I do agree that a 4 blade will give you the grip, hold the planing speed in conditions. As for sizing, remind me what the gear ratio and WOT range is for that year/model.

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Patrick - A few thoughts for you to consider.

First of all, as Phil suggests, I am absolutely positive the engine is up too high. With a Mercury engine, this puts the anti-vent plate 2-1/4" above the water flow, which Mercury says is the realm of high performance sport, flats and racing boats. It is too high for an offshore Whaler. Originally, Whaler recommended the engine on an Outrage 18 be run 3/4" high, but better prop technology has allowed more running height, and the 1-1/2" setting can be used with success for maximum all around good performance. Nothing is gained by going over 1-1/2" high on a Whaler.

Note that I am using anti-vent plate height above water, and NOT bolt hole convention. Theoretically, if all engines were created equal, and all shaft lengths the same, the bolt hole convention would work, mainly 3/4" difference between each hole. This is the mistake being made and a lot of bad information is being given because of it. With the exception of the Mercury mid range engines, 75-125HP, which have VERY long shaft lengths, the Mercurys that I am familiar with seem to be at least the same as the convention, or even a little bit SHORTER. From what I can tell, the 20" and 25" designations vary from manufacturer to manufacturer. Much of this disinformation has arisen because of the Evinrude E-tec engines, which seem to have a longer than standard shaft length. They can therefore be bolted on higher because of this. For instance, it is widely accepted through testing, that an E-tec 90 on a Montauk CAN be bolted on in the highest set of holes, meaning 3 open holes above the bolts. But I doubt if it actually amounts to running the anti-vent plate 2-1/4" high. I tried this mounting height on a Montauk with a Merc in-line 6, and it was WAY too high for the prop to grab. So even though both engine are designated 20" shaft, the Merc is shorter(higher) than the E-tec and requires lower bolt hole mounting. I think this applies with your new Merc 150 also, which probably has a shorter shaft length then the E-tec 150. I know that to be the case on a Merc 150 that I own.

So, before spending $500 on a new prop, which may not be needed, drop the engine down a bolt hole. You will not loose top end and you will solve the offshore condition situation.

Another alternative, for about the same price as a new SS prop, is to install a 4" or 6" setback jackplate, simple to do with no other changes, and you will have instantly adjustable height for any condition. I recommend the Sea Star Solution (previously Detwiler) black anodized manual model, about $425. which is what I use

http://photobucket.com/gallery/user/l...jc=/?ref=1

Regarding props, the Stiletto you are using is basically similar to the Mercury Laser II, a prop Mercury has now discontinued for the large size gearcase. Their newer props simply make the large Laser II outdated. The new prop of choice for inshore and offshore center console boats is the Enertia. If you are going to spend for a new prop, that is what you want. Take a look at the performance reports on all of the new Whalers, and you will see the Enertia being used almost universally. They are a larger prop, with large blade area, and they provide great overall hull lift and fast top end. I am running a pair of them on my twin engine Outrage 25, and they are the best props I have ever run. If you buy an Enertia, be sure to also use the Flo-Torq IV anti clutch rattle hub kit. Mercury also makes this same propeller under their lower cost Quicksilver branding, called a Q3, for less money but without the venting system. See here:

https://www.generalpropeller.com/prop...er-name/q3

And finally for less money, if you want to consider a lower cost aluminum prop, Mercury's new Spitfire 4 blade prop is quite good, with excellent acceleration, holding and no loss of top end that most 4 blades have. The Quicksilver version is called the Nemesis.

Keep us posted with your results and decisions.

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Thanks for the input Phil and Larry, much appreciated.

In response, the Mercury Enertia is a recommendation I'll look into. Specifically, see if I have a prop shop in the area that does loaners. I won't consider an aluminum prop due to the power and speed potential. And I don't have length in my garage for even a short setback bracket, it has to go in diagonally already.

As to the engine mounting height, thats another distinct consideration. Measured from the keel, the AV plate is 2 1/4" up as noted by Finnegan. Not sure how that translates in distance to the water when underway.

Any other thoughts on appropriate 4 blade options are appreciated. Comments on props others are running on this relatively common rig would be great as well.

Patrick
Milwaukee, WI

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The installation guide that comes with all Mercury outboards contains an engine mounting height graph. These show that a 2-1/4" height for the anti-vent plate is only recommended for boats that run between 60 and 70 MPH top end. Patrick, if you drop the engine down a hole, you won't have to spend at least $500 for an Enertia prop, as the Stiletto should work fine. On an Outrage 18 with single Mercury engine, the 3rd (middle) hole mounting should be ideal.

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Larry's suggestion of lowering your motor 1hole is the solution to your problem. If your reported top speed id 51+ MPH, you are already going faster than one might expect. Unless I have your gear ratio wrong, your prop slip is only 3. That kind of number is high speed racing boat class. Lowering the engine 1 hole will not take more than a 1/2 mile of speed, and most likely can be restored by running at maximum tilt.