stilleto on my yamaha 60

[cleve]

i have posted earlier about my 60 yamaha with a 2.33-1 gear ratio on a stick steer bass boat. i am overpowered a little (rated for a 50) and the large gearcase really isn't suited for my boat but it is what it is. i have a 19 pitch yamaha prop now and av plate is raised one bolt hole on transom(about 3/4 inch above keel, semi-v). i think i could raise more but have not yet. my max rpm wot, trimmed wide open is 5700-5800(range is 4500-5500). my top speed is 38-39 mph(gps) which i think is lacking. hole shot and midrange is excellent. i'm thinking a 21 pitch quality prop and raising the motor more would theoretically be more suited for my setup(big motor,light boat). the turning point web page says 19 pitch for heavy loads and 21 pitch for top speed. the stiletto advantage 1 21 pitch 13 1/4x21(stainless) is $215. this is the more affordable prop that i have looked at. i am trying to make an educated guess and not spend a huge amount of money. is the stiletto a quality prop? am i doomed with the large gearcase which is for heavy loads and not performance? if so, what could i do to unleash this motor? like i said, low and midrange are phenominal and it feels like i should be screaming on topend but i'm not.

 

[cleve]

Re: stilleto on my yamaha 60

could someone at least tell whether the stiletto advantage 1 is a good choice.

 

[Rocky_Road]

Re: stilleto on my yamaha 60

i have posted earlier about my 60 yamaha with a 2.33-1 gear ratio on a stick steer bass boat. i am overpowered a little (rated for a 50) and the large gearcase really isn't suited for my boat but it is what it is. i have a 19 pitch yamaha prop now and av plate is raised one bolt hole on transom(about 3/4 inch above keel, semi-v). i think i could raise more but have not yet. my max rpm wot, trimmed wide open is 5700-5800(range is 4500-5500). my top speed is 38-39 mph(gps) which i think is lacking. hole shot and midrange is excellent. i'm thinking a 21 pitch quality prop and raising the motor more would theoretically be more suited for my setup(big motor,light boat). the turning point web page says 19 pitch for heavy loads and 21 pitch for top speed. the stiletto advantage 1 21 pitch 13 1/4x21(stainless) is $215. this is the more affordable prop that i have looked at. i am trying to make an educated guess and not spend a huge amount of money. is the stiletto a quality prop? am i doomed with the large gearcase which is for heavy loads and not performance? if so, what could i do to unleash this motor? like i said, low and midrange are phenominal and it feels like i should be screaming on topend but i'm not.

I think that you will find that the Stiletto is one of the most respected props, by members of this forum. I have one on my Mercruiser 470, and my Mercruiser 3.0...and love them!

One thing to consider, though.

I am almost sure that the Stiletto is a progressive pitch design. That means that the stamped pitch, is actually the average pitch of the total prop's range (in the case of a 19"...prop performs from 17", to 21"...depending upon the forward, and rotational, speed). You may find that you will have to control your max RPM's, with your throttle. That's what I do....

 

[Frank Acampora]

Re: stilleto on my yamaha 60

Raising the engine is going to raise the RPM some and you are already too high. With a 2.33 ratio lower unit, I think a 21 pitch prop would definitely be a good choice. It would probably take the RPM down to about 5300. ( 2 inch pitch increase usually lowers RPM by about 400-500) I think if you compare the theoretical top speeds and the actual you are getting now, Theoretical with a 19 pitch at 57-5800 will be either close or the same as a 21 pitch with 5300 RPM. The actual top speed will most likely be higher by about 2-5 MPH with the 21 pitch because less power is wasted turning the higher pitch prop through the water at a slower RPM so more engine power is used to actually drive the boat forward.

Think about it this way: A propeller has a defined thickness to the blades and leading edge. It takes a certain amount of power to just move the blade through the water. All other things being equal, the faster you try to move it, the more power it will take. Don't believe it? Take your hand with the fingers together and flat. Dip it into the water vertically while the boat is moving slowly. Not much resistance. right? Now do it while the boat is going 30. Pushes your hand back a bit, doesn't it? Takes a lot more effort on your part to keep it vertical.

However, theory being just that--theory, It would be best to try to find a loaner prop to test before buying.

 

[cleve]

Re: stilleto on my yamaha 60

thanks guys

 

[cleve]

Re: stilleto on my yamaha 60

I think that you will find that the Stiletto is one of the most respected props, by members of this forum. I have one on my Mercruiser 470, and my Mercruiser 3.0...and love them!

One thing to consider, though.

I am almost sure that the Stiletto is a progressive pitch design. That means that the stamped pitch, is actually the average pitch of the total prop's range (in the case of a 19"...prop performs from 17", to 21"...depending upon the forward, and rotational, speed). You may find that you will have to control your max RPM's, with your throttle. That's what I do....

been thinking about what rocky road said on the progressive pitch design and i guess i don't fully understand what that means. wondering if you could explain a little more for an ignorant soul like myself.

 

[cleve]

Re: stilleto on my yamaha 60

i also forgot to say that my prop now is aluminum.

 

[Rocky_Road]

Re: stilleto on my yamaha 60

been thinking about what rocky road said on the progressive pitch design and i guess i don't fully understand what that means. wondering if you could explain a little more for an ignorant soul like myself.

A progressive pitched prop, is pitched lower at the leading edge, and higher at the trailing edge...enabling the prop to better adjust to the current power band requirement. In short...it is like putting a 3, or 4, speed transmission in your outdrive.

The technical stuff can get overbearing...but here is a quote from a prop gurhu, and then some simple links to descriptions (and drawings) of what a progressive prop is designed to do:

"Props come in a variety of configurations known as flat pitch, regressive pitch and progressive pitch. Props with a flat or straight pitch have the same pitch on the leading edge as on the trailing edge and are usually considered the fastest. Props with a progressive pitch are the most common and are the best for overall performance, these have a lower pitch on the leading edge for hole shot purposes and a higher pitch on the trailing edge for speed. These props are generally stamped with a median number, an example being a prop stamped 25 pitch will more likely read 27 to 28 pitch under the cup when measured on a pitch gauge..."

http://books.google.com/books?id=XZ...X&oi=book_result&resnum=10&ct=result#PPA14,M1

http://shopping.msn.com/reviews/sti...ropeller-3-blade-13-25-dia-x-17-pitch-st21317

http://www.rundquist.com/how_change_pitch.htm

 

[cleve]

Re: stilleto on my yamaha 60

thanks again. i understand progressive pitch now. i'm seriously considering ordering the advantage 1.

 

[Rocky_Road]

Re: stilleto on my yamaha 60

thanks again. i understand progressive pitch now. i'm seriously considering ordering the advantage 1.

You have got my curiosity...can you post a link?

Have you considered eBay for your prop? I found a perfect Stilleto, for $90....

 

[cleve]

Re: stilleto on my yamaha 60

i did look on ebay and did not see a 21 pitch advantage.

 

[cleve]

Re: stilleto on my yamaha 60

sorry if i'm beating a dead horse, but i was wondering if i should go with a 19 instead of a 21 being it's progressive pitch? i was planning on raising motor more on the transom which raises rpm's right? i'm concerned about the ss prop 21 bringing my rpm's to low, but the manual says output is 60hp @ 5300 rpm. i am overpowered a little , on a lighweight boat. do ya'll think the 21 would drop the rpm's too low even though i'm a little high now with 19 pitch aluminum?

 

[cleve]

Re: stilleto on my yamaha 60

i hate to revive an old post but i've just now got around to buying and testing my new prop(stilleto 21). went out yesterday by myself, 2 batteries, fishing gear etc. and wind was a little stout and there was a pretty good chop on the water. anyway, i was disappointed with the prop. it performed fine with hardly any noticable differance than the aluminum 19 pitch. my gps batteries died so i can't give you an accurate top speed but it may have been 1-2 mph faster if that. here's the kicker, top rpm's were no more than 4600-4700. like i said it was hard to get a good run going with the wind and chop but that's all i got. is it possible to lose that many rpm's by going up one size in pitch. i also raised motor one more bolt hole, no venting problems. i feel like i am wasting my time and that i wasted my money. would iboats allow exchanges? it seems like with evrything i've tried the performance is still the same, good hole shot and midrange with no topend and now i'm lugging the motor with low rpm's. could someone steer me in the right direction?

 

[Dhadley]

Re: stilleto on my yamaha 60

Just shows what a good bite that prop has. The trick is what you've already said - you raised it and it didn't vent. Go up more. You simply need to dial in the set up for that prop. You're already faster and have better acceleration. As you go up and lose drag you'll gain even more.

 

[Rocky_Road]

Re: stilleto on my yamaha 60

i hate to revive an old post but i've just now got around to buying and testing my new prop(stilleto 21). went out yesterday by myself, 2 batteries, fishing gear etc. and wind was a little stout and there was a pretty good chop on the water. anyway, i was disappointed with the prop. it performed fine with hardly any noticable differance than the aluminum 19 pitch. my gps batteries died so i can't give you an accurate top speed but it may have been 1-2 mph faster if that. here's the kicker, top rpm's were no more than 4600-4700. like i said it was hard to get a good run going with the wind and chop but that's all i got. is it possible to lose that many rpm's by going up one size in pitch. i also raised motor one more bolt hole, no venting problems. i feel like i am wasting my time and that i wasted my money. would iboats allow exchanges? it seems like with evrything i've tried the performance is still the same, good hole shot and midrange with no topend and now i'm lugging the motor with low rpm's. could someone steer me in the right direction?

Based upon the pitch range of a progressive pitched prop, you have installed a prop that runs from 19" to 23". That explains the loss of rpm's at WOT.

You should have seen better results from a 19" Stilleto...at both ends of the spectrum.

I suspect that you 'felt' a hole shot improvement, by going from an aluminum prop (flexes), to the stainless steel.

 

[cleve]

Re: stilleto on my yamaha 60

hole shot was good but i wouldn't say better than the aluminum, about the same. at wot you could definately tell the motor was not anywhere near top rpm range. as far as height goes i'm about 2 inches above the keel now. it still amazes me that i lost 1000 rpms. it seems like the 19 still would not get me in range. theoretically where would i stand with a 17 or 19 pitch?

 

[Dhadley]

Re: stilleto on my yamaha 60

You went from a 19 aluminum with probably little rake or cup to a quality 21 ss with pretty decent cup (in angle and placement) and probably more rake. Assuming the aluminum prop was in great shape and you tested at the same X dimension, the ss prop did exactly what would be expected - the same speed at less rpm. If the aluminum prop was worn at all, visable or not, there's more of the improvement.

Now, we'll max out the set up for the new, and different style, prop. Start by raising the motor. That should improve everyting from holeshot to top rpm. Once you do that and can get a good test in on decent water we'll know more.