updated: tried re-propping a Yam 150; look at these numbers; too big?

[Home Cookin']

SEE UPDATE BELOW

I think from my numbers the prop I just tried is too big, that is, it's lugging my motor. Do you agree?

My objective is to replace the "stock" alumuinum with a stainless, for better performance, durability (shallow water/sandy bottom) and to have a spare.

I ran the old prop and immediately ran the new, so all conditions are equal.
2003 21' Sea Hunt center console, bottom paint, 150 Yam 2 stroke TXRB (basic motor). The "old prop" numbers are consistent w/ the published test data, just a little lower, which could be the paint. I use it for general family use; top speed is not a goal, though.

Old prop 141/2 x17 alum:
3000rpm 21mph
4000 30-32
5000 39
5500 top 41.5

Hole 3 sec

New prop 15x19 SS
3000 24.5
4000 34-36
4700 top 41-43

Hole 5 sec

A reputable boat shop is selling some overstock and used props at great prices, and I can take the new one back. others they have in my motor's range are a 15 1/4" x 17" and a 14" x 19". Since I'll take a painted prop, I have options. So if you agree that the 15x19 is too agressive, which should I try next?

thanks!

 

[wildspeed]

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

I run the the same engine 150 TXRZ(2001) on a KW 2020DC.

Replaced the 17 stock aluminium with a 14-1⁄4 x 18 Performance Serie 3 Blades (MAR-GYT3B-V6-18)

Run 44 MPH at 5300 with a 1/2+ load.

Tried running a 14-1/4 x 17 Reliance Serie (68F-45972-00-00), performances were very close to the 18 but the engine started the chatter and rattle noise at idle and slow speeds. (Making me nuts...)

Put back the 18 and noise was gone. Also been thinking about trying a performance 4 blades (MAR-GYT4B-V6-18),

 

[Home Cookin']

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

thanks. I got a lot of vibration with the 19 at low speeds

so I don't know if it's better to get more pitch/less diameter (14x19) or more diameter/same pitch (15 1/4 x 17) than what I have (14 1/4 x 17)?

 

[wildspeed]

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

I don't think the 15+ diameter are recommended for those engines.
Here is the list of yamaha prop
http://www.yamaha-motor.com/outboard/powermatched/08_prop_pdfs/150~300, F150 ~F250.pdf

You could try the 19, but seems to much pitch. i think something close to your al prop dimension will be your best bet since those performance # look pretty good

 

[Dhadley]

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

It sounds like you're trying different styles of props without changing the motor height. If you are not going to adjust the set up you'll be better off to go from the 14 1/4 x 17 aluminum to a standard14 1/4 x 15 stainless.

 

[PROPer]

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

You want to be sure that your motor can get to the the correct RPM range. In your case it should be 5500 - 5800 RPM. I would recommend trying a SS prop that is close in size to your existing AL prop. It sounds like you were proped correctly.

 

[Home Cookin']

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

thanks, all.
wildspeed, that chart is very interesting: it appears that even a 1/4" in diameter takes a prop off the recommended list. I didn't realize that the tolerance was that low. but meanwhile the numbers apply to motors from 150-300: I would not have thought the 150 can handle the same prop as a 300 can.
There's always so much to learn!

 

[Dhadley]

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

It's not so much the diameter itself but what they do with the extra blade area. Typically a larger diameter prop will have more technology in the blades. That will, in most cases, allow you to move the motor higher which results in less drag which means increased efficiency.

There are props with 13 3/4" diameter that bite harder than props with 14 1/4" diameter.

 

[Home Cookin']

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

I took a SS 151/4 X 17 on trial basis. It was a windy day but I tried to average the speeds and find calm water.
Old prop 141/2 x17 alum:
3000rpm 21mph
4000 30-32
5000 39
5500 top 41.5

New prop
3000 21.6-23
3500 28.5
4000 32-32.7
5000 39.3
top 5100-5300 40-41
really hard to get to 5300 But as I said before, I get no increased response when I push the throttle the last 2 inches, and I wander if I am leaning out the motor.
Great hole shot

should I keep it and not worry about the top end? My purpose is to get a SS for shallow water, rather than for speed, and I usually run around 3500. Local marine shop is having a "yard sale" so I get it for $250. Thre's a 14 x 19 but I think I learned that the 19 is too much. Thoughts? Thanks, all!

 

[Dhadley]

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

Once again - if you are testing the props at the same height then you are not getting the full potiental from the props with more technology. While you may not be concerned with top speed you will need to make sure the chosen prop allows the motor to reach the top end of the target rpm. The 19 ss probably does have too much bite at this motor height. You can do 1 of 2 things - raise the motor and test the 19 again or if you are not going to change the motor height then test a 14 1/4 x 15 ss prop.

 

[Home Cookin']

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

thanks, dhadley, and just to confirm, you are referring to raising the motor on the transom (unbolt and rebolt) and not to trimming the motor up with the PTT (which I did)?

 

[Cannondale]

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

thanks, dhadley, and just to confirm, you are referring to raising the motor on the transom (unbolt and rebolt) and not to trimming the motor up with the PTT (which I did)?

That's exactly what he meant....unbolting the motor from the transom, raising it a mounting hole or two, then rebolting it to the transom.

I was taught long ago that, as a rule of thumb with everything else being kept the same (mounting height, etc.), that when moving from an AL to SS prop, to achieve the same rpm range, you drop the pitch by 2" and keep the same diameter. So Dhadley's suggestion of testing out a 14 1/4 x 15P SS prop is what you really need to do. Obviously the SS props you've tested aren't correct for the boat.

 

[Home Cookin']

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

sorry to be tiresome but I am learning and appreciate all the help. the recommendation for a 14 1/4 x 15 makes sense, but that combo is not shown on the yamaha chart posted above. There's a:
14 1/2 by 15 reliance,
a 14 1/4 x 16 performance,
14 1/4 x 17 reliance (wildspeed says it rattles, he has the same motor and a similar boat)
14 1/4 x 18 performance (recommended by wildspeed).
(my current alum is the stock 14 1/2 x 17)
I just don't know enough to know if 1/4 inch diameter difference is that important. I'm leaning toward WS's recommendation even though the pitch is moving in a different direction.
Like everyone 'd like to save some $$ by getting either one of the close-out props from the store, or a used/refurbished from the prop shop or a used boat store nearby. If I save $ on a sale/used prop with a bigger diameter but then have to spend the savings on time/money to raise the motor, I'm not getting ahead.

thanks all and I hope this exercise is helpful for other readers; I know I have learned a lot here.

 

[Dhadley]

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

If you're not going to change the motor height I'd go with a 3 blade 15 in stainless. If you are willing to work with engine set up I'd be willing to bet that you might be able to spin a good 19 stainless. All things being equal if you can spin a 19 at 5700-5800 you'll obviously be going faster than spinning a 17 at 5700-5800.

 

[wildspeed]

Re: tried re-propping a Yam 150; look at these numbers; too big?

Re: tried re-propping a Yam 150; look at these numbers; too big?

Home Cookin' what the last update ?