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After asking around on this site about props someone suggested raising my 2003 90hp yamaha 2 stroke up on my 1988 Montauk to get better rpms and overall better performance. Im greatly considering raising the engine very soon, as in tomorrow soon. I just looked at the engine and it isn't All the way down on the transom. It's about an inch above it. The ventilation plate is pretty much in line with the bilge drain tube. I was wondering if this seems good as it is or should I go up one hole? As of now the engine is on the first hole (counting from the top down.) any help is greatly appreciated

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**The ventilation plate is actually about an inch below the bulge drain tube

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What holes are the bolts inserted in the engine bracket?
http://www.whalercentral.com/articles...cle_id=106

Let us know.

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It is bolted all the way down as represented in the diagram from the link you provided above.

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The bolt is in the first hole

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That is too low....

Some engines can be raised all the way up, however, I would start off by mounting it in the third hole which would be 2 holes up...

If you have any problems with the lower holes, see this article.
http://www.whalercentral.com/articles...icle_id=82
However, you shouldn't have any problems with your 1988 model....

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Ok so you think moving the engine up two holes?

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That is where I would start... 2 holes up, the bolts in the 3rd holes..

Also, see this post where he mounted his engine 2 holes up and his report....
http://www.whalercentral.com/forum/vi...rowstart=0

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Thank you for the fast response Joe. It's greatly appreciated

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How high you mount the motor depends, to some extent, on what propeller you are using.

Can you tell us what propeller you are using now? Brand, model and size? If you're not sure what brand and model it is, look for a part number on it and I can decipher that for you.

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Tom,
The prop I was previously Using was a Yamaha 13 1/4x17. The prop I will be putting on and using is Solas 13.5x15. Th reason for change is the old prop is in rough shape and needs reconditioning. The prop I'm putting on is a spare I hot with the boat

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By the way, I may put the original prop on during the season. A friend can get me a good deal during the summer to recondition the prop.

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But which Yamaha 13-1/4x17? Aluminum? Painted Stainless Steel? Performance Series? Which?

Don't bother with your spare Solas. It doesn't even matter which model of 13-1/2x15 it is, it is too little pitch for that motor.

NEVER run a damaged prop on an outboard motor. Replace it, or get it fixed first.

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In terms of how high to raise the motor, it will be more efficient to raise it three sets of bolts holes first, not just two.

If you raise it three sets of bolts holes (all the way up) and the boat performs fine, you are done. If you are not happy and lower it one set of bolt holes, you've moved the motor twice.

If, on the other hand, you move the motor up two sets of bolts holes and it performs fine, you still do not know if three holes up will be better, so you have to move it to the highest position to find out. Now you've moved the motor twice. If you then find out the motor is too high you have to move it back down a set of bolt holes, at which point you will have moved the motor three times, not just one or two.

Based on my experience and the experience of many others, I think you will find your Yamaha 90 will do just fine mounted as high as it can go on the transom of your Montauk. I have yet to hear of one single person who mounted their Yamaha 90 all the way up on the transom of a Montauk and found they had to lower it back down a set of holes.

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It's a k series aluminum prop made by Yamaha.

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OK. I don't think you should spend money trying to repiar it. Just buy a new one or better yet, get a good stainless steel prop. It will be, by far, the best $250 you ever spend on your boat's performance.

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Tom,

Is there any brand of motor on a 16'7" Classic Whaler that you do not recommend raising all the way up?

I see you mention E-Tec and Yamaha raising them all the way but what about the other brands?

Maybe we should start an article?

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Tom,
I just called a local Yamaha dealer, they'd have to order the prop for me and it would be $150. I looked online and found them for $125 on a site, then found a couple on eBay for $100. I think I will just get the same prop as I have now and wait till I get some money to purchase a stainless steel one. I did however raise the motor two holes up.(I didn't see your post in time). It was fairly easy, only took about an hour. Thank you for all the help guys. I really appreciate it.

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**The prop mentioned above is the same type as the one I have now.

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Did you have a chance to try it out yet?

I don't mind moving the engine up or down as it is fairly simple as you found out.

So the prop you are using and now buying a new one, is a Yamaha 13 1/4x17 K Series.....?

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I did not have a chance to try it out and might not for a little while. I wouldn't mind doing it again if I had to. It is fairly simple

Yes that's the prop which I used and will most likely buying

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It's not about brand so much as the particular model and the particular propeller being used. As I have said elsewhere, my thinking (and personal experience) on this subject has evolved very slowly. It is dawning on me that I have yet to hear of anybody complaining that mounting an outboard as high as it can go on the transom of the classic 16'-7" Whalers will not work and results in excessive ventilation.

However, I suspect that if a guy were using an aluminum propeller, like Whalkin88's 13-1/4" x 17" Yamaha Aluminum propeller, the highest mounting position be result in excessive ventilation, but since I only use stainless steel propellers, I cannot address that possibility myself. As we all know, aluminum propellers cannot support as much cupping and always result in lost performance because of their thicker blades and more conservative blade geometry as well as the flexing it suffers under load.

I would also hesitate to mount a smaller motor with the 3-1/2" (3.5) gearcase as high as it can go, but again, we need somebody to try it to find out what will really happen.

One thing I do know, is that the traditional all-the-way-down and the one-hole-up mounting positions that were used 25 years ago are obsolete for all motors and propellers made today. There is no reason for a motor to be mounted so low on the transom of a classic 16'-7" Whaler. None whatsoever. Long time experienced dealers and mechanics need to get over this primitive practice and get with the program.

Note on Yamaha propeller nomenclature: "K" Series is NOT a model of propeller. It simply identifies a propeller as having a 4-1/4" (4.25) hub diameter and meant for a 4-1/4" gearcase.

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Tom,

Thank your for the clarification on the propeller. On the Yamaha chart for props next to series it just says aluminum. Here is the chart I'm looking at:

http://www.yamaha-motor.com/outboard/powermatched/2010_props_oct_14_10/60~130,%20T50~F115.pdf

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Yes, that is correct. The 13-1/4" x 17" Yamaha Aluminum prop is part # 6E5-45945-01-EL.

That model is one of the very few propeller models Yamaha offers that is not made by Precision Propeller Industries, Inc. I believe it comes from a manufacturer in Japan.

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I believe I read somewhere that Precision Propellers and Solas propellers merged together, I believe they are the same company

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No, that is completely false. Solas is a Taiwanese manufacturer. They sell aftermarket props and make some for Honda.

Precision Propeller Industries, Inc (PPI) started as an aftermarket manufacturer of Stiletto and Turbo brand propellers. They also made propellers for Yamaha and other manufacturers.

In 2007 Yamaha was so happy with them they bought the whole company from its founder Jim Booe. Yamaha has expanded their manufacturing facilities and distribution network while they still manufacturer the Stiletto and Turbo branded propellers.

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In answer to Joe's question, I would say yes, brand matters. First of all, not all engine brackets have the same number of mounting holes. So "all the way up" has different implications by brand.

Some smaller and older Mercs only have three holes, the Evinrudes and Yamahas only have four, but most Mercs have five. Five holes is WAY UP (3") and can be too much. To be clear, the issue here is the running height of the anti-ventilation plate over the water flow coming off the bottom of the hull. This can be complicated, since it varies with speed and engine setback, and is very difficult to determine while underway at high speed. By setting the engine trim correctly and parallel with the boat bottom, you can visually measure this while on the trailer, a good starting point. If the plate is not so high in this situation that the water inlet holes would be exposed, you are probably all right, since there is always some swell rise and you should not be sucking air. Figuring out water swell coming off the transom at various speeds is more difficult, and basically required individual testing. Water pressure gauges are valuable when going for maximum height and speed.

One of the ways you can determine what is too much is by measuring from the underside of the ant-ventilation plate to the top of the water inlet holes. About 1/4" less than that dimension is your maximaum safe running height, regardless of prop choice. If you get the top water inlet holes above the water flow line, you are sucking air into your cooling and risking engine distruction.

The other brand issue is mid-section ACTUAL length. This can vary from the advertized 20, 25 and 30" listings. I can tell you for a fact that mid-range Mercs, 75-125 HP, and also the Big Foots, are taller than advertized, which means they can more easily tolerate elevated transom heights. I do not have information on the other 4 major brands.

In summary, holes on the transom bracket, or where the holes are drilled in the boat, are only a starting place. What counts is how high the anti-vent plate is running over the flow coming off the hull. I have found that for standard aluminum and SS props, 3/4" over flow provides good results. For performance props like most of the Mercury SS models, 1-1/2" gives optimum performance. Once you are up to 2-1/4" and higher over flow, you are in the realm of high performance top speed applications, not suited for Whaler type of offshore boating. This type of installation often requires low water pickups.

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Tom,

I think that is my point.... (for an article)

Many people don't want to spend $250 for a new prop...

For those with an older motor and an aluminum or older Stainless Steel prop, raising the motor 2 holes will probably help their performance without having to spend the money on a new prop...

Certainly, if someone wants to get the best performance, raising the motor to the optimum height and purchasing a new prop will accomplish what they are after....

I know on my prior Montauk I would have had better performance, less spray from the cavitation plate, and without having to purchase a new prop....

Still thinking about this for an article......

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Joe,
You mentioned raising your engine will lessen the engine spray?
I used to get a a lot of spray from the transducer, now since I've raised the engine do you think it will lessen the rooster tail or should I just move the transducer up?

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Whalin,

The transducer is another story...
Yes, you would need to adjust that to lessen the spray from it.

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Thank you Joe

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Larry makes a valid point that different motors have different midsection lengths, but it is NOT brand specific which is why I said it depends on the articular model of motor being discussed, not just its brand.

As an example, Mercury has models with the AV plate higher or lower, there is no standard for that distance. Larry cites several examples.

It is a common mistake to confuse the distance between the motor mounting bracket and the AV plate with the nominal "Shaft Length" They are not the same thing. "Shaft Length" is simply the height of the transom a given motor is designed to fit, nothing more.

Nor is motor mounting height simply a matter of getting the AV plate a certain distance above or below the surface of the water or the keel. It is not that simple.

Larger diameter propellers will need to have the propeller shaft itself, not just the AV plate, set lower in the water for the blade tips to wind up at a certain position relative to the surface of the water.

How the boat is used has to be considered as well. The level of the water's surface is always going to change with boat speed. It is NOT a static elevation that can be easily gauged.

If all if this makes setting motor mounting height complicated for a Montauk, fret not. For all the hundreds of propellers about there, there are not that many that will fit the typical motor used on the typical Montauk.

Likewise, the typical Montauk does not use a huge variety of motors, most are in the 50-100 HP class and use 4-1/4" geracases and props.

Furthermore, the typical Montauk goes between 25 and 50 MPH, a fairly common range so we don't need top consider extreme applications of propeller and motor mounting heights like we might if we were discussing some 80 MPH high performance boat.

Lastly, there are hundreds of thousands of small Whalers out there. Collectively, Whaler owners have a LOT of experience with setting them up and selecting propellers for all the common outboard motors used. A quick search of the discussion archives will reveal this topic discussed over, and over, and over again.