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Author Topic:   Grocks' Props

grocks posted 10-20-2009 02:46 AM ET (US)
I have a 2003 Yamaha 90 2 stroke on my 17 montauk I am looking for just a standard stainless prop who knows the correct size of prop i would be looking for
deepwater posted 10-20-2009 06:22 AM ET (US)
You can try a search in here or back channel Tom Clark,,He will have many questions as to your intended use like fresh or salt water how your boat is loaded do you do lots of trolling or long high-speed runs or how many ppl do you normally carry do you boat in fast moving water do you want speed or power are you pulling skiers ,,Questions like that so he can give you several types of props suggestions
jimh posted 10-20-2009 08:40 AM ET (US)
What is the gear ratio of a 2003 Yamaha 90-HP two-cycle engine?
number9 posted 10-20-2009 10:35 AM ET (US)
The gear ratio of a 2003 Yamaha 90-HP two-cycle engine is 2.00.
Tom W Clark posted 10-20-2009 10:58 AM ET (US)
There is no such thing as a "standard prop" or a "correct size" for every given boat/motor combination. There are, however, certain models of propeller that are known to work well.
When choosing a propeller size one needs to start with the basic parameters:
- Speed of the boat
- Recommended WOT RPM range of the motor(s)
- WOT RPM of the boat as currently propped
- Gear ratio of the motor(s)
- Size (especially pitch) of the current propeller
- Specific model of the current propeller
In this case we know, thanks to Bill, the gear ratio, 2:1. Not much other information is provided so let's do some homework.
Off the top of my head, I believe the recommended WOT RPM range of this motor is 5000-5500 RPM.
A Montauk with a 2003 Yamaha 90 two stroke should be capable of reaching 40-42 MPH.
Using the Propeller Calculator in the Reference Section, http://continuouswave.com/cgi-bin/propcalc.pl , we can plug in what we know and, assuming propeller slip of 10 percent, and the desired WOT RPM of 5500 RPM, it tells us you would need 17-1/2" of pitch to get there.
Well, there is no 17-1/2" pitch propeller out there so 17" pitch would be the closest.
This is a good pitch recommendation for the Yamaha Painted Stainless Steel propeller which is a good fit on the Montauk.
We also know from prior experience that another good model of propeller is the Stiletto Advantage but the Advantage generally will produce results with little or no (calculated) prop slip, so in this case I would recommend you reduce pitch to 15" if selecting this model of propeller.
number9 posted 10-20-2009 11:23 AM ET (US)
Tom,
4500-5500 RPM recommended WOT range per the owner's manual.
Bill
Tom W Clark posted 10-20-2009 11:28 AM ET (US)
I stand corrected. How does that alter the propeller recommendations offered above?
deepwater posted 10-20-2009 07:21 PM ET (US)
See ^@^,,Hey Max
L H G posted 10-20-2009 07:48 PM ET (US)
A Mercury Vengeance 18" would be a good choice for this engine/boat combination. I like the polished SS type prop over those black Teflon coated ones that Yamaha sells.
Tom W Clark posted 10-20-2009 07:57 PM ET (US)
The 18" Vengeance is too much pitch, though the 16" Vengeance might be OK. Try one if you can get you hands on one.
The Yamaha Painted Stainless Steel propellers are, not surprisingly, painted, not Teflon coated.
Polished props like the Stiletto, Mercury and Yamaha Performance Series (which is nothing more than a Stiletto Advantage with a different name) are much prettier...and likely to be stolen.
Polishing does absolutely nothing to enhance performance, it just makes them prettier.
jimh posted 10-20-2009 08:46 PM ET (US)
Buffing and polishing a stainless steel propeller to a high luster also increases the cost, but without any performance benefit, it's really just boat bling.
Tom W Clark posted 10-20-2009 08:57 PM ET (US)
Oh, absolutley. A polished surface attracts propeller buyers. It has nothing to do with the quality of the prop.
PowerTech Propellers is great in that they offer all their stainless steel propellers in either a Polished finish or a Satin finish.
The Satin finish is usually about $30 less.
RJG posted 10-20-2009 10:56 PM ET (US)
One might also say the polished prop attracts propeller thieves.
L H G posted 10-21-2009 01:29 AM ET (US)
You guys really are amazing (and cheap too it appears). If you like your black SS props, be my guest. Go for it. But not classy enough for my Whalers! I'll take my chances with the crooks. I like Merc's high end shiny props like Rev-4's, Enertia's, Tempest Plus, and Laser II's.
Mercury says that when a pitch calculation comes out bewteen available props, like 17-1/2", to go up to the next number. Hence my recommendation for 18".
I can't believe a Yamaha 90 on a Montauk, with 2.0 gears, can't turn an 18. I know someone with a old "throwback" Merc 90 tower on a Montauk, also 2.0 gears, and it will turn a 21" Laser II to 5000, which is the same as a 19" Laser II to 5500. So the less powerful Yamaha 90 should be able to turn an 18. So should an E-tec 90 for that matter?
But then again, maybe I'm overestimating the power of those 3 cylinder 90's, and a 17 is a better fit.
jimh posted 10-21-2009 09:14 AM ET (US)
There is nothing wrong with boat bling, and a lot of people enjoy it and admire it. But in the case of the propeller, a polished and highly reflective surface on the propeller blades doesn't make the boat go faster. A highly polished propeller might help with fishing; maybe it will attract fish more effectively than a dull or painted propeller. The irony of the polished propeller is when it's in use you can't see it.
Peter posted 10-21-2009 09:45 AM ET (US)
The Yamaha black painted stainless steel K-series propeller, 17 inch pitch, would be a good choice for a Yamaha 90 2-stroke on a 17 Montauk. With some patience, you should be able to get a used one on e-bay for about $150. Typically, some of the black paint wears off on these propellers and often times people just sand off the rest of the paint making the propeller have an unpolished stainless steel look.
number9 posted 10-21-2009 10:14 AM ET (US)
Tom,
Sorry about the WOT reference, wasn't trying to correct you, I just didn't see your 5,000-5,500 reference. Must have had one of those close to senior moments.
Bill
Tom W Clark posted 10-21-2009 10:58 AM ET (US)

quote:
Mercury says that when a pitch calculation comes out between available props, like 17-1/2", to go up to the next number. Hence my recommendation for 18".
This is a perfect example of why it is not always such a good idea to blindly make all your choices based on manufacture's promotional literature.
In this case we have a great body of knowledge with the particular boat in question, the motor and the propellers being considered. We know the 17" Yamaha Painted Stainless Steel Propeller is a good fit. We also know the Stiletto with two inches less pitch will yield about the same RPM as the Yamaha prop.
We also know the intermediate gearcase size Vengeance to run as if it is has a little more pitch than stated so it seems reasonable, that in the case of this model, to choose the next lower pitch rather than the next higher pitch.
Personal experience trumps a regurgitated rule-of-thumb any day of the week.
L H G posted 10-21-2009 02:39 PM ET (US)
Well, Tom, I would have to agree with your statement in most cases:
"...it is not always such a good idea to blindly make all your choices based on manufacturer's promotional literature"
Many feel that way about Evinrude's advertizing and attacks on the Yamaha 4-strokes, and the Mercury "head-to-head" engine testing advertizing!
BUT, Mercury is widely respected in the propeller business, something I know you agree with, and makes an excellent product for any line of engines. So in this particular situation, I think what they say and advise can be taken seriously. In the interest of selling as many propellers as they can, it would make no sense to promote a propeller only to have the customer unhappy with it. I have followed their guidelines and prop decriptive applications, with good success. I can't think of any other engine or prop company that is such a wealth of information on outboard propellers and their proper selection and application.
If you go to their on-line prop calculator, you will see that when a pitch calculation comes in at a mid-point fraction, they always recommend the next pitch up, rather than down. In general, this gives better performance, higher top end and lower fuel use, while still keeping the engine within a 500 RPM max band.
Now if the 18 Vengeance is a higher efficiency prop, showing up as a higher than rated "effective pitch", that I wouldn't know, since I do not have a boat that uses this particular model propeller. But I do know thye are an excellent prop line, and deliver really solid performance and top end speed.
Peter posted 10-21-2009 04:11 PM ET (US)
Mercury makes some good propellers and they make some that would probably serve better as a paper weight than a propeller.
My experience with the Mercury on-line prop calculator is that it always recommends a propeller that I know has too much pitch based on experience.
Tom W Clark posted 10-21-2009 04:16 PM ET (US)
The Vengeance is an OK prop. It would not be my first choice for a Yamaha 90 on a Montauk.
The trouble for Mercury, which offers a wide assortment of props for large outboards and sterndrives, is that they offer very little for intermediate gearcase motors.
For pitches 19" and above, they offer the Laser II. For pitches 18" and below, they offer the old Vengeance. That's it for stainless steel three blade propellers.
I'll put a Stiletto Advantage up against a Vengeance any day of the week.
jimh posted 10-21-2009 09:41 PM ET (US)
Mercury's propeller calculator has always computed propeller selections for my application which have proved to be completely unsuitable when I actually bought or borrowed the recommended propeller and tried it.
15ft90hp posted 10-21-2009 11:05 PM ET (US)
Put on a 5-6" manual jackplate, and get the motor up and out in clean water than put a 19 pitch Lazer II on her.
Those props like to run up in shallow water.
jimh posted 10-22-2009 01:03 AM ET (US)
I agree with Tom's recommendation; start with a 17-inch pitch propeller.
grocks posted 10-22-2009 01:24 AM ET (US)
thanks for all your comments you all are so informed on the subject. My use is limited to basic day use with some fishing and a little watersking application. Just all around family use.
Tom W Clark posted 10-22-2009 10:21 AM ET (US)
Yes, the Yamaha Painted Stainless Steel, Performance Series, Mercury Vengeance and Stiletto Advantage are all excellent propellers for general day use, fishing and waterskiing.
grocks posted 10-23-2009 12:49 AM ET (US)
Looked on ebay this this what I should be looking for? What is the 13 and a quarter mean as well as left hand
NEW, STILETTO , ADVANTAGE II , stainless steel prop , 13 & 1/4 " x 17 " LEFT HAND , part # 30217 , YAMAHA
Tom W Clark posted 10-23-2009 01:05 AM ET (US)
13-1/4 is the diameter as measured in inches.
"Left hand" is slang for counter-rotation, in other words, it is designed to rotate the opposite direction of what you need.
deepwater posted 10-23-2009 04:34 AM ET (US)
Left hand is for a 2 motor set up,,One prop spins clockwise and the other spins counter clockwise to off set the torque effect of the motors,,You need clockwise
Slick 50 posted 10-25-2009 10:16 AM ET (US)
I will likely get my hand slapped for saying this but I have had good experience with propping the 90 HP Yamaha for 6000 RPM rather than 5500 RPM. The boat's all around performance will improve significantly.
Rick

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Author	Topic: Grocks' Props
grocks	posted 10-20-2009 02:46 AM ET (US) I have a 2003 Yamaha 90 2 stroke on my 17 montauk I am looking for just a standard stainless prop who knows the correct size of prop i would be looking for
deepwater	posted 10-20-2009 06:22 AM ET (US) You can try a search in here or back channel Tom Clark,,He will have many questions as to your intended use like fresh or salt water how your boat is loaded do you do lots of trolling or long high-speed runs or how many ppl do you normally carry do you boat in fast moving water do you want speed or power are you pulling skiers ,,Questions like that so he can give you several types of props suggestions
jimh	posted 10-20-2009 08:40 AM ET (US) What is the gear ratio of a 2003 Yamaha 90-HP two-cycle engine?
number9	posted 10-20-2009 10:35 AM ET (US) The gear ratio of a 2003 Yamaha 90-HP two-cycle engine is 2.00.
Tom W Clark	posted 10-20-2009 10:58 AM ET (US) There is no such thing as a "standard prop" or a "correct size" for every given boat/motor combination. There are, however, certain models of propeller that are known to work well. When choosing a propeller size one needs to start with the basic parameters: - Speed of the boat - Recommended WOT RPM range of the motor(s) - WOT RPM of the boat as currently propped - Gear ratio of the motor(s) - Size (especially pitch) of the current propeller - Specific model of the current propeller In this case we know, thanks to Bill, the gear ratio, 2:1. Not much other information is provided so let's do some homework. Off the top of my head, I believe the recommended WOT RPM range of this motor is 5000-5500 RPM. A Montauk with a 2003 Yamaha 90 two stroke should be capable of reaching 40-42 MPH. Using the Propeller Calculator in the Reference Section, http://continuouswave.com/cgi-bin/propcalc.pl , we can plug in what we know and, assuming propeller slip of 10 percent, and the desired WOT RPM of 5500 RPM, it tells us you would need 17-1/2" of pitch to get there. Well, there is no 17-1/2" pitch propeller out there so 17" pitch would be the closest. This is a good pitch recommendation for the Yamaha Painted Stainless Steel propeller which is a good fit on the Montauk. We also know from prior experience that another good model of propeller is the Stiletto Advantage but the Advantage generally will produce results with little or no (calculated) prop slip, so in this case I would recommend you reduce pitch to 15" if selecting this model of propeller.
number9	posted 10-20-2009 11:23 AM ET (US) Tom, 4500-5500 RPM recommended WOT range per the owner's manual. Bill
Tom W Clark	posted 10-20-2009 11:28 AM ET (US) I stand corrected. How does that alter the propeller recommendations offered above?
deepwater	posted 10-20-2009 07:21 PM ET (US) See ^@^,,Hey Max
L H G	posted 10-20-2009 07:48 PM ET (US) A Mercury Vengeance 18" would be a good choice for this engine/boat combination. I like the polished SS type prop over those black Teflon coated ones that Yamaha sells.
Tom W Clark	posted 10-20-2009 07:57 PM ET (US) The 18" Vengeance is too much pitch, though the 16" Vengeance might be OK. Try one if you can get you hands on one. The Yamaha Painted Stainless Steel propellers are, not surprisingly, painted, not Teflon coated. Polished props like the Stiletto, Mercury and Yamaha Performance Series (which is nothing more than a Stiletto Advantage with a different name) are much prettier...and likely to be stolen. Polishing does absolutely nothing to enhance performance, it just makes them prettier.
jimh	posted 10-20-2009 08:46 PM ET (US) Buffing and polishing a stainless steel propeller to a high luster also increases the cost, but without any performance benefit, it's really just boat bling.
Tom W Clark	posted 10-20-2009 08:57 PM ET (US) Oh, absolutley. A polished surface attracts propeller buyers. It has nothing to do with the quality of the prop. PowerTech Propellers is great in that they offer all their stainless steel propellers in either a Polished finish or a Satin finish. The Satin finish is usually about $30 less.
RJG	posted 10-20-2009 10:56 PM ET (US) One might also say the polished prop attracts propeller thieves.
L H G	posted 10-21-2009 01:29 AM ET (US) You guys really are amazing (and cheap too it appears). If you like your black SS props, be my guest. Go for it. But not classy enough for my Whalers! I'll take my chances with the crooks. I like Merc's high end shiny props like Rev-4's, Enertia's, Tempest Plus, and Laser II's. Mercury says that when a pitch calculation comes out bewteen available props, like 17-1/2", to go up to the next number. Hence my recommendation for 18". I can't believe a Yamaha 90 on a Montauk, with 2.0 gears, can't turn an 18. I know someone with a old "throwback" Merc 90 tower on a Montauk, also 2.0 gears, and it will turn a 21" Laser II to 5000, which is the same as a 19" Laser II to 5500. So the less powerful Yamaha 90 should be able to turn an 18. So should an E-tec 90 for that matter? But then again, maybe I'm overestimating the power of those 3 cylinder 90's, and a 17 is a better fit.
jimh	posted 10-21-2009 09:14 AM ET (US) There is nothing wrong with boat bling, and a lot of people enjoy it and admire it. But in the case of the propeller, a polished and highly reflective surface on the propeller blades doesn't make the boat go faster. A highly polished propeller might help with fishing; maybe it will attract fish more effectively than a dull or painted propeller. The irony of the polished propeller is when it's in use you can't see it.
Peter	posted 10-21-2009 09:45 AM ET (US) The Yamaha black painted stainless steel K-series propeller, 17 inch pitch, would be a good choice for a Yamaha 90 2-stroke on a 17 Montauk. With some patience, you should be able to get a used one on e-bay for about $150. Typically, some of the black paint wears off on these propellers and often times people just sand off the rest of the paint making the propeller have an unpolished stainless steel look.
number9	posted 10-21-2009 10:14 AM ET (US) Tom, Sorry about the WOT reference, wasn't trying to correct you, I just didn't see your 5,000-5,500 reference. Must have had one of those close to senior moments. Bill
Tom W Clark	posted 10-21-2009 10:58 AM ET (US) quote: Mercury says that when a pitch calculation comes out between available props, like 17-1/2", to go up to the next number. Hence my recommendation for 18". This is a perfect example of why it is not always such a good idea to blindly make all your choices based on manufacture's promotional literature. In this case we have a great body of knowledge with the particular boat in question, the motor and the propellers being considered. We know the 17" Yamaha Painted Stainless Steel Propeller is a good fit. We also know the Stiletto with two inches less pitch will yield about the same RPM as the Yamaha prop. We also know the intermediate gearcase size Vengeance to run as if it is has a little more pitch than stated so it seems reasonable, that in the case of this model, to choose the next lower pitch rather than the next higher pitch. Personal experience trumps a regurgitated rule-of-thumb any day of the week.
L H G	posted 10-21-2009 02:39 PM ET (US) Well, Tom, I would have to agree with your statement in most cases: "...it is not always such a good idea to blindly make all your choices based on manufacturer's promotional literature" Many feel that way about Evinrude's advertizing and attacks on the Yamaha 4-strokes, and the Mercury "head-to-head" engine testing advertizing! BUT, Mercury is widely respected in the propeller business, something I know you agree with, and makes an excellent product for any line of engines. So in this particular situation, I think what they say and advise can be taken seriously. In the interest of selling as many propellers as they can, it would make no sense to promote a propeller only to have the customer unhappy with it. I have followed their guidelines and prop decriptive applications, with good success. I can't think of any other engine or prop company that is such a wealth of information on outboard propellers and their proper selection and application. If you go to their on-line prop calculator, you will see that when a pitch calculation comes in at a mid-point fraction, they always recommend the next pitch up, rather than down. In general, this gives better performance, higher top end and lower fuel use, while still keeping the engine within a 500 RPM max band. Now if the 18 Vengeance is a higher efficiency prop, showing up as a higher than rated "effective pitch", that I wouldn't know, since I do not have a boat that uses this particular model propeller. But I do know thye are an excellent prop line, and deliver really solid performance and top end speed.
Peter	posted 10-21-2009 04:11 PM ET (US) Mercury makes some good propellers and they make some that would probably serve better as a paper weight than a propeller. My experience with the Mercury on-line prop calculator is that it always recommends a propeller that I know has too much pitch based on experience.
Tom W Clark	posted 10-21-2009 04:16 PM ET (US) The Vengeance is an OK prop. It would not be my first choice for a Yamaha 90 on a Montauk. The trouble for Mercury, which offers a wide assortment of props for large outboards and sterndrives, is that they offer very little for intermediate gearcase motors. For pitches 19" and above, they offer the Laser II. For pitches 18" and below, they offer the old Vengeance. That's it for stainless steel three blade propellers. I'll put a Stiletto Advantage up against a Vengeance any day of the week.
jimh	posted 10-21-2009 09:41 PM ET (US) Mercury's propeller calculator has always computed propeller selections for my application which have proved to be completely unsuitable when I actually bought or borrowed the recommended propeller and tried it.
15ft90hp	posted 10-21-2009 11:05 PM ET (US) Put on a 5-6" manual jackplate, and get the motor up and out in clean water than put a 19 pitch Lazer II on her. Those props like to run up in shallow water.
jimh	posted 10-22-2009 01:03 AM ET (US) I agree with Tom's recommendation; start with a 17-inch pitch propeller.
grocks	posted 10-22-2009 01:24 AM ET (US) thanks for all your comments you all are so informed on the subject. My use is limited to basic day use with some fishing and a little watersking application. Just all around family use.
Tom W Clark	posted 10-22-2009 10:21 AM ET (US) Yes, the Yamaha Painted Stainless Steel, Performance Series, Mercury Vengeance and Stiletto Advantage are all excellent propellers for general day use, fishing and waterskiing.
grocks	posted 10-23-2009 12:49 AM ET (US) Looked on ebay this this what I should be looking for? What is the 13 and a quarter mean as well as left hand NEW, STILETTO , ADVANTAGE II , stainless steel prop , 13 & 1/4 " x 17 " LEFT HAND , part # 30217 , YAMAHA
Tom W Clark	posted 10-23-2009 01:05 AM ET (US) 13-1/4 is the diameter as measured in inches. "Left hand" is slang for counter-rotation, in other words, it is designed to rotate the opposite direction of what you need.
deepwater	posted 10-23-2009 04:34 AM ET (US) Left hand is for a 2 motor set up,,One prop spins clockwise and the other spins counter clockwise to off set the torque effect of the motors,,You need clockwise
Slick 50	posted 10-25-2009 10:16 AM ET (US) I will likely get my hand slapped for saying this but I have had good experience with propping the 90 HP Yamaha for 6000 RPM rather than 5500 RPM. The boat's all around performance will improve significantly. Rick