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After mounting my new etec one hole up using lag bolts in the bottom holes, I convinced my mechanic to move it to the three hole up position as advised repeatedly on this site. He did an outstanding job . The new bottom holes entered the splash well very close to the old "blind" holes allowing a large washer to cover them almost completely. I took her for a short test spin yesterday after picking her up. Although conditions were far from perfect (10 knot winds and a light to moderate chop) I was able to reach 40 mph (GPS) at WOT at 5500 RPMs. I was a bit concerned that it was at the top of the recommended RPM range (5000-5500) for this engine. I would be grateful for any prop suggestions which might improve performance for this set up. I am currently running an aluminum prop 13 3/4 X17. We have a lot of shallow water and submerged rocks here so I don't want to run a stainless prop. When this motor was mounted one hole up, it was running 38.5 mph at 5200 RPM. So I did not see quite as much performance improvement as I was expecting. Again though, it might be explained by water conditions. I have also noticed that the steering is rather squirrely with this new motor. Steers fine if trimmed up to the perfect position, but a hair lower or higher results in rather violent pull to port or starboard. Is this normal? Maybe I was just spoiled by my old 90 spl which I never had to trim at WOT. I think I will be pleased with this motor once I get used to it. Right now I can take comfort in knowing it will stay attached to the transom with bottom through bolts. Goodbye and good riddance lags!

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I have an E-TEC 90 mounted three holes up on my 1984 Montauk 17. At idle speeds the steering is not affected much by trim but when on plane it is a bear to handle trimmed down. I had looked at a Yamaha 70 before I went for the E-TEC but the salesman told me that having to run through shallow water to the lake I should opt for an aluminum prop to avoid engine damage if I hit something. In my opinion he didn't know what he was talking about so I went elsewhere. Outboard propellers ride on a rubber hub designed to slip should the prop hit something. Modern stainless steel propellers are surprisingly tough and can withstand hits that would destroy an aluminum prop. If you hit a sandbar with an aluminum prop you will need to have it repaired or replaced. With Stainless steel you raise the engine, push the boat off the bar then go on your way.

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What size SS prop do you use with your etec?

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Since you asked for propeller recommendations, I will give mine. Disclaimer - Most people here know I am a Mercury guy, so take that into consideration.

First of all, a Nauset is a lighter hull than a Montauk, so it should run faster under most conditions. Most Montauk owners here indicate an average top speed of 40MPH with an Evinrude 90 raised up as yours is, some a little more, and some a little less, So you are in the ballpark already. You MAY be able to get 42 or 43 with a better prop. Also remember, not all engines of a given brand and HP are created equal, so some speed depends on what you got off the production line.

Regarding the alum vs SS prop applications, I have a fairly fast Montauk and for different purposes I use both, either a Mercury Black Max aluminum, or Mercury Laser II SS performance prop, both in the same pitch. From my observations and testing, the Mercury aluminum props are the best you can buy, if you want aluminum, and perform remarkably well. They have recently come out with a new 4 blade aluminum, which they say is just as fast as the three blade, but with better acceleration and holding. It's called a Mercury Spitfire or Quicksilver Nemesis. Do some research on it. Without hub kit, one can be purchased for about $110-$120. Someone here is now running one of these on his Etec 90, and says it performs very well, better than his previous "generic" aluminum prop did..

So if you want aluminum, I would recommend a 4 blade "Spitfire" or "Nemesis" for your rig, in 17" pitch. It should give you more speed and better holding than what you have, especially since you are raised up.

One last thing. to eliminate propeller torque feedback to the wheel, set your trim tab straight back, and for any given speed, trim the engine for equal (neutral) pull in both directions. That is you most efficient running trim position, and gives maximum speed. These are Mercury's recommendations, not mine. The trim tab can be used to counter feedback, by setting it to the right when looking at the engine from behind. but this is most useful only for slower running speeds and rought conditions when the engine has to be trimed way in. Otherwise, I would not do it. At higher speeds like 40 MPH and up, it will slow top speed (more drag) and cause more problems than it corrects. So the stright position works best and gives the best performance. I have used this prinicple for 30 years with no problems at all.

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The old bolt holes should be filled with wooden plugs (not dowels) and sealant at a minimum.

13.75x17 does not mean anything if you don't list the make and model.



This is exactly why you should be using a stainless steel prop. It will take more to damage it then aluminum.

The E-TEC 90 hp motor has been installed on dozens of 16 and 17 foot models and heavily tested using different props.

The recommended props include:

13-1/4" x 15" Stiletto Advantage 4.25 (soon to be discontinued)
13-7/8 x 17 OMC SST II

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Thanks Finnegan for the tips. All good advice. Actually, I am not at all unhappy with 40 mph. I rarely go that fast anyway. But, I am more worried about the high RPMs. Would a SS prop lower my RPM ?. The only reason I am running aluminum is that I was advised that hitting one of the large submerged rocks around here with a SS prop could severely damage the engine whereas with an aluminum prop, engine damage would be less likely. But if that advice is incorrect, I would certainly rather be running SS. I suppose the best idea would be to not hit a rock, but they do move around a lot!

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Phil, I did not mean to suggest that the washers were used to fill or seal the old holes, I was only saying that cosmetically, they partially hide the old holes which were properly filled. I was incorrect about the prop size. It is actually a 13.25 X 17 Evinrude Model 765183. Sorry for the mistake. Also, I have received much conflicting advice about SS vs alum props and impact damage. Just to be clear, I am not so concerned about damage to an aluminum prop as they are relatively cheap and easy to replace. But isn't a SS prop going to be much less forgiving, therefor transfer more of the impact to the engine lower unit. This what I hear around here all the time.

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The four blade Mercury Spitfire will bring your RPM's down about 100-150 RPM I would imagine, with no loss in top end. If the RPM's remain the same, then you will get more top end speed. I doubt if you can go up to any 19" pitch prop without losing 400 RPM.

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I have a 1966 modified Currituck with a 1989 90 -2 stroke Yamaha mounted three holes up. The prop is black painted Yamaha, stainless steel. Sorry I can't tell you the size or pitch it is 150 miles away.
I was running 43 MPH at 5100 RPM and it had some throttle left to go. It was plenty fast. I too would be more than happy with 40 MPH but you are not running efficiently with an aluminum prop. If you try stainless one time you will never own aluminum again.

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The general consensus seems to be that a SS prop will improve performance on the new etec. I want to make one more test run on smooth water to get a little better idea where I'm at now before I make any changes. I guess I'm one of those who doesn't like change too much, and probably over-thinks everything. Thanks all for sharing your knowledge.

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Any chance you could put some photos of the engine mounted on the third hole up ?
With maybe a shot of the bottom of the boat and where it lines up on the engine shaft ?
Thanks for the report ;) looking at this set up for my 1972 Katama

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Yes, I will try to do that. I would welcome some input anyway on whether this motor is too high.

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I hope this link works for photos. It should show the new etec mounted three holes up. I also tried to show the cavitation plate in relation to the keel. I wasn't sure what trim position would be best for this. So the motor is simply trimmed perpendicular to the floor. I placed a straight edge on the plate and measured where the straight edge meets the transom. It landed about 2.5 - 3.0 inches above the keel. Of course it would be lower on the sternum if the motor was trimmed up. Does this seem excessively high? I was looking for 1.5 inches when mounted three holes up. I know I will need a test drive with two persons on board to check for ventilation. Any advice would be appreciated.


http://s1067.photobucket.com/user/bud...age=1</a>

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That height works well for a lot of us. I was out waterskiing with that setup all day yesterday including very tight and almost full throttle turns pulling a skier in the intracoastal and my Viper 17" never slipped at all.

Chris

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Thanks Chris. That's a beautiful Nauset you have there. Makes me wish I had redone my hull while the motor was off.

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bcross,

My boat and motor are almost identical to yours. My motor is mounted all the way up. Using the measurement method you illustrated, I see three inches above the keel. When I raised my motor last year, I switched to a stainless steel 13-1/4" x 15" Stiletto Advantage propeller. Since that time, I have observed slightly better performance overall with absolutely no negative effects.

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Tom,

It would make a difference on where the top holes were originally drilled. 1 1/2 inches or 2 inches from the top as an example.
Then the lower holes would have a difference of a half an inch.

You don't mention what lower holes you drilled.
Green or Yellow? Or something all together different.
http://www.whalercentral.com/articles...icle_id=82

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Joe, I can answer that question for my boat. The top bolts are exactly 1 7/8" OC from the top of the transom just as shown in your diagram. Bottom bolts are in the green holes.

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Outstanding.
That is the info we all need from everyone that responds.
That way we all know for sure and can see if there is any difference between the mounting holes.

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bcross, Awesome !!! photos are perfect thank you..... going to use my 1976 Evinrude this summer and put on the ETEC this winter !!!

thanks for posting !!

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Me too.