Prop recommendations for 1986 Evinrude 90HP on Montauk

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Author Topic:   Prop recommendations for 1986 Evinrude 90HP on Montauk

wjriling posted 06-07-2005 08:53 AM ET (US)
Hello all,
Any recommendations for aluminum propeller for 1986 Evinrude 90HP on my Montauk? Size, brand, etc.
Thanks for all your help!
Regards,
Wendy
Teak Oil posted 06-07-2005 09:58 AM ET (US)
Please use the search function, this has been talked about many many times.
I like OMC aluminum props and use a 13x19 for light loads
Tollyfamily posted 06-07-2005 12:59 PM ET (US)
Same setup with 13X17 gives me 5500 rpm.
Dan
WHALETEX posted 06-07-2005 01:21 PM ET (US)
The stock OMC 3 blade aluminum in 17 pitch for Montauks with moderate loads and skiing. Same prop in 19 pitch for light loads. For very heavy loads (maybe overloads) I have used the same prop in a 15 pitch to pop the boat up, but you must watch the rpm to keep from overreving once on plane. These props are readily availble used and rebuilt at most prop shops, boat dealers, and on the net and they represent a good value.
A good setup is both a 19 and 17. Put the one on the motor that best fits the need of the day and keep the other aboard for a spare. Also keep several spare cotter pins (don't reuse), a spare nut, spare washer that goes under the nut, a spare thrust washer that goes behind the the prop, and a wrench to fit the nut.
jimh posted 06-07-2005 01:38 PM ET (US)
There are more articles and threads about the propellers and performance for MONTAUK 17 than any other boat model, and most of those are for a 90-HP situation. My advice would be to read some of those previous articles.
Or just get a three-blade 17-inch pitch and start from there.
LHG posted 06-07-2005 08:04 PM ET (US)
With a Merc 2-stroke 90 on a Montauk, the aluminum prop of choice is a 21" pitch, 2.33 gear ratio. But it is a poor performer compared to an SS model.
The Chesapeake Explorer posted 06-07-2005 09:31 PM ET (US)
13 1/4 X 17 !
jimh posted 06-07-2005 10:27 PM ET (US)
Here are 90 other discussions on propellers, Montauks, and 90-HP:
http://continuouswave.com/cgi-bin/sw.pl?Search=propeller+montauk+90-HP
jimh posted 06-07-2005 10:30 PM ET (US)
If those articles aren't enough, try this one, with leads to many more:
http://continuouswave.com/whaler/reference/16-17/repower.html
rumrunner posted 06-14-2005 04:50 PM ET (US)
Interesting. 1986 90hp Evinrude on Montauk, 13x19 prop, WOT 4200 rpm 32 s.o.g according to GPS
Seems like you guys do quite a bit better. Thinking of switching to a 13x17 to go skiing and tubing.
Teak Oil posted 06-17-2005 09:19 PM ET (US)
rumrunner your engine is performing very poorly and certainly needs to see a mechanic.
Only getting 4200rpm I bet you are not even running on all cylinders
Joe Kriz posted 06-17-2005 09:40 PM ET (US)
We haven't seen wjriling here in 10 days so I don't know if he is still interested.

Question?
Why do most people bring up the diameter of the prop?
It has absolutely nothing to do with anything except for the engineers...
The only thing that matters is the pitch... Let the engineers keep track of the rest. Example, cupped, double cupped, etc... Just think about pitch in the beginning.
I agree with Chesapeake Explorer and jimh, try a 17 pitch OMC aluminum prop.
rumrunner,
your 19 pitch seems too much for your setup. I would also try a 17 pitch and go from there. As others have mentioned, your engine should be up a minimum of 1 hole.
I had the same problem on my Montauk as many others have had by the dealer installing the engine using the blind holes and the engine was mounted all the way down. I never did raise my engine because I did not want to fill the holes. Many times though, I wished I had.
Two factors on getting your engine up to the recommended WOT RPM's is the prop and the mounted engine height.
Unless of course you still have your trailer attached underneath the boat or are dragging a sea anchor.. :-)
For the engine height... First rule of thumb is make sure you are not throwing a large rooster tail from the cavatation plate.. This will tell you immediately your engine is too low.
After that, try other props to get your engine up to the recommended WOT set by the manufacturer. For many OMC's it was either 4500 to 5500 rpm's or 5000 to 6000 rpm's... Anything other than the above and you are not even in the playing field. (read your manual for other brands of engines).
Let us know what you come up with and make sure your tach is working properly when you run the tests.
rumrunner posted 06-18-2005 08:51 AM ET (US)
Joe,
Good suggestions here. I'm going to go through each of your points. I noticed on a couple of occasions late last summer the tach (which is a 6000 rpm tach) fluctuated a little, so I had the OMC shop check it out this winter. Naturally, when they did there was no problem.
Teak oil,
the reason I don't think it is a powerhead issue is that it is about 5 hrs. out of a tune-up, carb rebuilding, thermostat change and everything was fine. It runs absolutely flawless in terms of starting, acceleration. Has 300 hrs on it, and compression on all cylinders is excellent. Did have some water issues in the fuel this spring, but the Racor filter seemed to straighten that out. It is definitely running on all cylinders, and gives absolutely no indications of having any powerhead issues. That's what has lead me to suspect prop/trim/mounting combo is to blame. I'm curious to see the difference the 13x17 will make.
Bottom line, I'm more curious than concerned. A top end of 4200 rpm doesn't cramp my style for what I do, and the waters I'm in usually prohibit running anything close to that anyway.
Joe Kriz posted 06-18-2005 04:34 PM ET (US)
rumrunner,
Here is the answer to your curious question that way I see it.
You can run almost any prop on your boat at 3,000 RPM. Is it the right prop?
Probably not.
Look at it like this. How much work is your engine doing to keep the rpm's at 3,000? The engine may be working too hard even though it is running at 3,000 rpm. In this case, even though the motor is running 3,000 rpm's, it is working too hard. Maybe not getting the optimum fuel mileage, etc...
I am exaggerating here, but you could probably turn a 3 foot diameter prop at 1,000 rpm... Would that work for us if all we wanted to do is 1,000 rpm?
No, the engine would be working way too hard. I think you get my point here.
The engine manufactures list the WOT rpm's in their manual for a reason.
You want the correct prop on your engine to achieve these recommended WOT rpm's. Then, when you are running at 3,000 rpm (example), your engine will be working as it should. It is not straining nor is it loafing. It is working as it the load was designed for.
You want the right prop to achieve the correct rpm's for your particular engine.
Your engine will most likely last longer and you will have the optimum fuel economy.
What tach are you using? Even though many brands are being sold and used for, let's say OMC, I would suggest and OMC tachometer. That's just my opinion. OMC designed the tach for their engines and that is what I stay with. You can buy them brand new on eBay fairly cheap if you don't have an OMC.
Second, get the right prop. I would start trying the 17 pitch OMC. Try borrowing one from someone first. When you get the right prop, you should be between 4500 and 5500 (read your manual to make sure about this) rpms at Wide Open Throttle with a light load and between 1/2 to full fuel tank(s).
rumrunner posted 06-18-2005 06:34 PM ET (US)
Joe,
All good points, and well taken. Re the tach, it is o.e.m., so I "assume" it is OMC (or endorsed by them), however, in absence of a logo on the face of it, can't be sure.
I'm going to try a 17 prop out of curiosity (need a spare anyway), and see how that works. Like I have said, don't feel as if there is a problem with the engine, just a matter of optimal prop/trim I believe.
Thanks for all the input!

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Author	Topic: Prop recommendations for 1986 Evinrude 90HP on Montauk
wjriling	posted 06-07-2005 08:53 AM ET (US) Hello all, Any recommendations for aluminum propeller for 1986 Evinrude 90HP on my Montauk? Size, brand, etc. Thanks for all your help! Regards, Wendy
Teak Oil	posted 06-07-2005 09:58 AM ET (US) Please use the search function, this has been talked about many many times. I like OMC aluminum props and use a 13x19 for light loads
Tollyfamily	posted 06-07-2005 12:59 PM ET (US) Same setup with 13X17 gives me 5500 rpm. Dan
WHALETEX	posted 06-07-2005 01:21 PM ET (US) The stock OMC 3 blade aluminum in 17 pitch for Montauks with moderate loads and skiing. Same prop in 19 pitch for light loads. For very heavy loads (maybe overloads) I have used the same prop in a 15 pitch to pop the boat up, but you must watch the rpm to keep from overreving once on plane. These props are readily availble used and rebuilt at most prop shops, boat dealers, and on the net and they represent a good value. A good setup is both a 19 and 17. Put the one on the motor that best fits the need of the day and keep the other aboard for a spare. Also keep several spare cotter pins (don't reuse), a spare nut, spare washer that goes under the nut, a spare thrust washer that goes behind the the prop, and a wrench to fit the nut.
jimh	posted 06-07-2005 01:38 PM ET (US) There are more articles and threads about the propellers and performance for MONTAUK 17 than any other boat model, and most of those are for a 90-HP situation. My advice would be to read some of those previous articles. Or just get a three-blade 17-inch pitch and start from there.
LHG	posted 06-07-2005 08:04 PM ET (US) With a Merc 2-stroke 90 on a Montauk, the aluminum prop of choice is a 21" pitch, 2.33 gear ratio. But it is a poor performer compared to an SS model.
The Chesapeake Explorer	posted 06-07-2005 09:31 PM ET (US) 13 1/4 X 17 !
jimh	posted 06-07-2005 10:27 PM ET (US) Here are 90 other discussions on propellers, Montauks, and 90-HP: http://continuouswave.com/cgi-bin/sw.pl?Search=propeller+montauk+90-HP
jimh	posted 06-07-2005 10:30 PM ET (US) If those articles aren't enough, try this one, with leads to many more: http://continuouswave.com/whaler/reference/16-17/repower.html
rumrunner	posted 06-14-2005 04:50 PM ET (US) Interesting. 1986 90hp Evinrude on Montauk, 13x19 prop, WOT 4200 rpm 32 s.o.g according to GPS Seems like you guys do quite a bit better. Thinking of switching to a 13x17 to go skiing and tubing.
Teak Oil	posted 06-17-2005 09:19 PM ET (US) rumrunner your engine is performing very poorly and certainly needs to see a mechanic. Only getting 4200rpm I bet you are not even running on all cylinders
Joe Kriz	posted 06-17-2005 09:40 PM ET (US) We haven't seen wjriling here in 10 days so I don't know if he is still interested. Question? Why do most people bring up the diameter of the prop? It has absolutely nothing to do with anything except for the engineers... The only thing that matters is the pitch... Let the engineers keep track of the rest. Example, cupped, double cupped, etc... Just think about pitch in the beginning. I agree with Chesapeake Explorer and jimh, try a 17 pitch OMC aluminum prop. rumrunner, your 19 pitch seems too much for your setup. I would also try a 17 pitch and go from there. As others have mentioned, your engine should be up a minimum of 1 hole. I had the same problem on my Montauk as many others have had by the dealer installing the engine using the blind holes and the engine was mounted all the way down. I never did raise my engine because I did not want to fill the holes. Many times though, I wished I had. Two factors on getting your engine up to the recommended WOT RPM's is the prop and the mounted engine height. Unless of course you still have your trailer attached underneath the boat or are dragging a sea anchor.. :-) For the engine height... First rule of thumb is make sure you are not throwing a large rooster tail from the cavatation plate.. This will tell you immediately your engine is too low. After that, try other props to get your engine up to the recommended WOT set by the manufacturer. For many OMC's it was either 4500 to 5500 rpm's or 5000 to 6000 rpm's... Anything other than the above and you are not even in the playing field. (read your manual for other brands of engines). Let us know what you come up with and make sure your tach is working properly when you run the tests.
rumrunner	posted 06-18-2005 08:51 AM ET (US) Joe, Good suggestions here. I'm going to go through each of your points. I noticed on a couple of occasions late last summer the tach (which is a 6000 rpm tach) fluctuated a little, so I had the OMC shop check it out this winter. Naturally, when they did there was no problem. Teak oil, the reason I don't think it is a powerhead issue is that it is about 5 hrs. out of a tune-up, carb rebuilding, thermostat change and everything was fine. It runs absolutely flawless in terms of starting, acceleration. Has 300 hrs on it, and compression on all cylinders is excellent. Did have some water issues in the fuel this spring, but the Racor filter seemed to straighten that out. It is definitely running on all cylinders, and gives absolutely no indications of having any powerhead issues. That's what has lead me to suspect prop/trim/mounting combo is to blame. I'm curious to see the difference the 13x17 will make. Bottom line, I'm more curious than concerned. A top end of 4200 rpm doesn't cramp my style for what I do, and the waters I'm in usually prohibit running anything close to that anyway.
Joe Kriz	posted 06-18-2005 04:34 PM ET (US) rumrunner, Here is the answer to your curious question that way I see it. You can run almost any prop on your boat at 3,000 RPM. Is it the right prop? Probably not. Look at it like this. How much work is your engine doing to keep the rpm's at 3,000? The engine may be working too hard even though it is running at 3,000 rpm. In this case, even though the motor is running 3,000 rpm's, it is working too hard. Maybe not getting the optimum fuel mileage, etc... I am exaggerating here, but you could probably turn a 3 foot diameter prop at 1,000 rpm... Would that work for us if all we wanted to do is 1,000 rpm? No, the engine would be working way too hard. I think you get my point here. The engine manufactures list the WOT rpm's in their manual for a reason. You want the correct prop on your engine to achieve these recommended WOT rpm's. Then, when you are running at 3,000 rpm (example), your engine will be working as it should. It is not straining nor is it loafing. It is working as it the load was designed for. You want the right prop to achieve the correct rpm's for your particular engine. Your engine will most likely last longer and you will have the optimum fuel economy. What tach are you using? Even though many brands are being sold and used for, let's say OMC, I would suggest and OMC tachometer. That's just my opinion. OMC designed the tach for their engines and that is what I stay with. You can buy them brand new on eBay fairly cheap if you don't have an OMC. Second, get the right prop. I would start trying the 17 pitch OMC. Try borrowing one from someone first. When you get the right prop, you should be between 4500 and 5500 (read your manual to make sure about this) rpms at Wide Open Throttle with a light load and between 1/2 to full fuel tank(s).
rumrunner	posted 06-18-2005 06:34 PM ET (US) Joe, All good points, and well taken. Re the tach, it is o.e.m., so I "assume" it is OMC (or endorsed by them), however, in absence of a logo on the face of it, can't be sure. I'm going to try a 17 prop out of curiosity (need a spare anyway), and see how that works. Like I have said, don't feel as if there is a problem with the engine, just a matter of optimal prop/trim I believe. Thanks for all the input!