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salmonboy -- We are discussing an Outrage 18 with a Honda BF150. You have a Mercury 150. Those two motors have different RPM ranges, and different gear ratios so it *might* be they need different propellers. Let's explore the possibilities for your boat in a new thread you start while we continue to discuss Tim's boat here. I have some solid advice for you I will share in your new thread.

Hi Tom,
Sorry, I have not been in the forum long and didn't mean to step in at the wrong time. The props I refer to above are Mercury aluminum. I don't know anything other than that. These props came with the boat and are obviously older than the motor.

Once agian, I have a 1986 Outrage 18 and a Mercury 150 Optimax. When I run the 19 pitch prop I don;t think I will reach the range. The 17 pitch prop does get me closter to the range from wjhat I can tell so far. I will continue to try and get a better read but can only do that when the seas permit. Any suggestions on what you think I should look at for a prop would be much appreciated.

Marc

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The Mercury OptiMax 150 uses a 1.87: 1 gear ratio and has a 5250-5750 RPM WOT engine speed range.

We know an Outrage 18 with 150 HP is good for 45-48 MPH so to get to that speed at 5750 RPM you'll need a 17" pitch propeller assuming it is a model of propeller that typically yields low calculated slip.

I do not recommend an aluminum prop be used on your boat. There is no good reason, except the costs savings for buying an aluminum prop and even that goes away after a while as it will not be as durable and long lasting as a stainless steel propeller.

The only propeller model that Mercury makes that is a particularly good fit here is the Laser II but Mercury does not offer it in pitches below 19" so it's out of consideration.

A better choice would be the 14-1/4" x 17" Stiletto Advantage 4.75. This is a very commonly fitted propeller on the Outrage 18s. It is also not very expensive at all.

You should also check and make sure the motor is mounted up at least two bolt holes (mounting bolts going through third, middle, set of holes in motor mounting bracket) as shown below.

o
o
o <-- Bolts should go through these holes. This is the "Two Holes Up" position
o
o

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Thanks Tom. This is great stuff. I will get the prop on order. As of now the motor is one hole up. I'll raise it to the next hole first chance I get. Will I notice any handling differance by raising the motor?

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Yes, the steering effort will be lighter.

You should not have to pay more than $250 for the Stiletto Advantage. You'll need the DE-501 hub kit or you can use a Flo-Torq hub kit if you already have one.

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I am not finding that prop for less than 280. Can you suggest a source? Also are you talking about the Advantage I, II or III? Some of the sites I looked at suggested only the 13 1/4 x 17 prop for that motor?

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The Stiletto Advantage I, II ad III are obsolete model names, though many vendors (and even some at the factory) still use the old names.

The current product is known as Advantage 4.25, Advantage 4.75 and Advantage Plus 4.75, the number indicating the size of the gearcase the propeller is designed to fit. For example, the Advantage 4.25 will fit intermediate size gearcases that have a bullet that is roughly 4-1/4" in diameter and use propellers with a hub that is 4-1/4" in diameter. This prop used to be known as the Advantage I.

The model names also represent the older version of the props that had pressed-in rubber hubs. Since 2006 or 2007 Stiletto has gone to a modular, field-replaceable hub kit and that is when they changed the model name. The propeller itself is unchanged, but have the ability to swab hubs allows one prop to be used on any brand of outboard with the appropriate hub kit.

(Almost) all Advantage 4.25 (I) propellers have a 13-1/4" diameter. (Almost) all Advantage 4.75 (II) have a 14-1/4" diameter. All Advantage Plus 4.75 (III) have a 14-1/2" diameter.

You need an Advantage 4.75 (II) with its 14-1/4" diameter. Whoever tried sell you a 13-1/4" diameter Stiletto does not know what they are talking about. That prop will not fit your motor.

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Its always better to buy a new propeller rather than repairing .Stainless propeller is better for achieving speed and also for good balance.

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Hi All, Its been a few years since this string started and the Stiletto(17P) has worked great, giving me a WOT at about 5300 rpm. The motor is mounted two holes up.

Over time I made some changes to the boat including a Yamaha 9.9 kicker and electric motor hanging on the transom. I modified the console and have all four of my batteries in there. Currently with all that, a half tank of gas and two guys (a normal load) I get up to 5100 rpm. I do want to get that higher and hope to get closer to 5750 rpm maximum if possible.

My questions are:
1. should I stick to the Stiletto and go to a 15 pitch?
2. Would a different motor height help?
3. is there another prop I should consider?
4. Would a cupped prop help?

Any suggestions or help would be most appreciated.

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1- Based on perfomance reports and your loading, yes. A 15" would be appropriate.
2 - It may. Trial and error will tell.
3. Possibly the Enertia but it is expensive
4. All prop blade designs have some degree of cupping.

With the added weight, you are below the sweet spot at WOT so dropping in pitch is recommended if you stayed with the same make/model.

While a 17"Enertia prop is typically recommended for the Optimax 150, given your added kicker, batteries, motor, I would start with the 15".

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Thanks Phil. I was hoping someone had some experience with heavier loads in the classic 18' outrage and could give some real life data. I think I am going to go with a 15P SST, probably a Mercury prop unless anyone has a better suggestion.