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I have repowered my 1989 Outrage 18 with an Evinrude 115 E-TEC and just love the engine. Now I'm dealing with every boat owner's greatest challenge: what prop do I use. The engine came with a 15" x 15" aluminum prop (bought the 2006 engine used, with 86 hrs on it). It turns 5700 RPM @ WOT.

That's OK, but it will not hold plane and will fall off in RPM's when I throttle back under 4000 RPM. I do not care to run over 35 MPH but I need to be able to run in the 3000-3500 RPM range when I'm in 3 ft seas. I'm thinking about going to a four blade prop to get more power with some sacrifice to the top end.

Please share all recommendations, especially if you have an Outrage 18 and have faced the same challenge.

Thanks, Dennis

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Dennis,

Something does not add up here. The 25" shaft length Evinrude E-TEC 115 (which I presume you have, as the Outrage 18 takes a 25" shaft motor) uses the V-6 size gearcase and a 2.25:1 gear ratio.

Are you telling us you can only hit 57570 RPM with that prop? It would not even be going 35 MPH at that engine speed.

What is your measured top speed?

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Top speed is about 34mph.

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Tom, I measured the speed with my gps, top speed 34.6mph. Thanks.

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That aluminum prop is absorbing/wasting more power than you think. Been there, done that. I don't know much about 4 blade props with that setup, but I'd guarantee you that putting the right sized 3 blade SS prop on will get you out of the hole better and be more responsive through your power range.

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Thanks Bo. Yes, I know that Alum props lose bite, power and flex too much. I'm trying to find a 13 7/8 X 17 to try out bebore a mess around with 4 blade props.

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OK, 34.6 MPH at 5700 RPM with a 15 inch pitch propeller is possible, though the calculated propeller slip is less than 4 percent, very low indeed.

Can you tell us what 15" x 15" aluminum prop it is? Is a BRP? Is there a part number?

A 13-7/8" x 17" will not fit your motor, it is for intermediate gearcase motors.

My first thought is a 14-1/4" x 15" Stiletto Advantage.

Also, what set of holes is the motor mounted with?

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Tom, now that we are coming out of winter down here on the gulf coast (and we really had winter this year with snow twice in Mobile and many dead mullet in the bay from the cold water), I am now ready to buy the right prop. I was told in another thread that you are the expert, so I appreciate your feedback.

To review, I have an "89 18 ft Outrage that I have repowered with a 2008 115 ETEC. Love the engine! Yes, 25" shaft with 2.25 gearcase. The cheap alum (no brand name) prop is 15 X 15, no cup. Engine is mounted on the 2nd hole and lines up just right with the transom. It get out of hole quickly, but will not hold plane/RPM's below 3800, @ 4500 RPM I cruise @ 28 mph and @ WOT 5600 I get 34.8mph on the GPS. I would like to get more speed if possible, max out fuel efficiency, but most of all be able to run @ lower RPMs in 2-3 ft seas. What is your recommended prop? I will get a stainless one. Do I want to go with a 4 blade?

Also, do you have any idea how much an '89 18 ft Outrage weighs? The old spec sheets says 1250 lbs dry, but that seems so low when you consider the new ones are 2000 lbs.

Thanks,

Dennis

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With a 2.0 gear ratio, and assuming the engine runs as strong as other brands of 115HP, and that your hull is dry and normally set up with no bottom paint, you should be running a SS 17" cupped prop, which should give you 40-42 MPH top end.

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Dennis,

I still recommend a 14-1/4" x 15" Stiletto Advantage 4.75 or a 14-3/4" x 16" Mercury Enertia.

You could try a four blade if holding plane at low speed is your primary goal, but most other aspects of performance will suffer.

I also recommend the motor be raised at least one more set of holes. It is too low now.

Yes, the classic Outrage 18 weighs 1250 pounds, though there has been some debat about that. The new 18s are completely different boats, much larger by volume, so you can't compare them.

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Thanks to all replies!

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The new prop is here! Big time kudos to Ken at www.Propgods.com for analyzing my statistics, listening to what I wanted to accomplish and recommending the right prop the first time. We exchanged several emails before we spent about 30 minutes on the phone. I'm in Mobile, AL, he's in Sarasota, FL. He had the same recommendation as Tom Clark, 14 3/4 X 16, but in a 4 blade SS prop. Bought it from him on Wed afternoon and it was here Friday morning shipped directly from PowerTech in Shreveport, LA, $379.00.

Here are the results: 1) Previously I could not hold rpm's under 3800 with my 15 X 15 alum prop on my '89 Outrage 18. Now I can hold any RPM speed. 2) I cruised @ 28 mph @ 4500 rpms with the old prop, now I can get 32 mph @ same rpms. 3) WOT previously was 34.8mph @ 5600 rpms. Now I'm just under 40 mph @ 5500rpms. Incredible.

Put it another way, I can cruise @ 28 mph at 400rpm less. Hello better fuel efficiency!

If any of you have an older Outrage 18 like mine and want to get away from the big 150 hp's like I did and drop down in HP and get better gph, speed and performance, put a 115 ETEC on your boat with a 4 blade 14 3/4 X 16 and you'll love it. I also need to move the engine from the 2nd hole to the 3rd like the bass boat guys do. Will probably get some more top end with the reduction in drag.

Another comment: these engines use so little oil when set up for the synthetic HD100 oil. I got the engine the end of August last year, have used the boat most weekends even through winter, and just finished my 2nd gal of oil last week.

Thank you Tom and all others for all your input. All of your info played a big role in leading me to the four blade prop.

Dennis

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Ken Reeves is a good guy.

I'm glad the new prop is working well for you but could you tell us what four blade 14-3/4" x 16" PowerTech prop you bought? They make quite a few different models.

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Tom, I got the Powertech SFS4, 14.25 X 16 SS. When I move the engine to the 3rd hole it will be optimized.

Thanks! Dennis

PS. Accidentally said 14.75" in a previous message.