8"x5-1/2" vs 8"x4-1/2" propeller for Evinrude Yachtwin 3hp?

[LargemouthBass21]

I stored my motor upright over the winter and the prop got broken somehow. It bothers me but there isn't much I can do now. The aluminum was very brittle so would've probably broken eventually. Anyway, I found a propeller for sale that is a 8"x5-1/2", (which is what the evinrude parts diagram suggests), but the broken one on my motor is a 8"x4-1/2". It lists the 8"x4-1/2" as optional. Would the 5 1/2 be a higher top speed or what? Mine is the non weedless model btw.

Thanks!!

 

[Crosbyman]

depends on load ...were you satisfied with what you had…? .Don't expect to much mph from a 3hp

 

[F_R]

As the name suggests, the Yachtwin was originally intended to be used on sailboats where high thrust is needed. However, a bunch of them wind up on fishing boats and the high thrust prop may cause over-revving. Thus the availability of a higher pitch prop to keep things under control.

 

[racerone]

On a canoe you might get some " speed " out of a 3 HP motor.

 

[LargemouthBass21]

On a canoe you might get some " speed " out of a 3 HP motor.

That’s exactly what I’m using it on! I have a cheapo sun dolphin canoe I got at a local sporting goods store. I have seen YouTube videos of people booking along pretty fast. So to get this clear, the 4 1/2 is the high thrust one?

 

[LargemouthBass21]

depends on load ...were you satisfied with what you had…? .Don't expect to much mph from a 3hp

Im fixing this up, I haven’t used it yet. I found it on the side of the road last fall. The price is right on the 5 1/2 and I think I will buy it.

 

[racerone]

You would want the 5 1/2 on a canoe.

 

[LargemouthBass21]

As the name suggests, the Yachtwin was originally intended to be used on sailboats where high thrust is needed. However, a bunch of them wind up on fishing boats and the high thrust prop may cause over-revving. Thus the availability of a higher pitch prop to keep things under control.

Thank you for that information, that helps a lot. Now is the 4 1/2 the high thrust one and the 5 1/2 the fishing boat one? I am using it on a small canoe in small lakes and rivers so I’d rather have a little more top end than high thrust.

 

[LargemouthBass21]

UPDATE: I ordered a brand new 8x5-1/2 for less than $20. Had its box and everything!

 

[Tim Frank]

Have you done some basic forensic checks on this motor?
A compression test would be a great starting point.
A new prop here, and in another thread new coils is more $$ than you might want to put into a zero compression motor.

 

[Crosbyman]

On a canoe you might get some " speed " out of a 3 HP motor.

agree ! beats rowing in the wind !


largemouth… pitch on a prop is like gears on a bike….


low gear (pitch) = bigger push with less speed
high gear (pitch) = less push more speed but a pain to get going

 

[LargemouthBass21]

agree ! beats rowing in the wind !


largemouth… pitch on a prop is like gears on a bike….


low gear (pitch) = bigger push with less speed
high gear (pitch) = less push more speed but a pain to get going

Makes sense to me, thanks!
i got a killer deal, a brand new 8x5-1/2 for $20 new!

 

[LargemouthBass21]

Have you done some basic forensic checks on this motor?
A compression test would be a great starting point.
A new prop here, and in another thread new coils is more $$ than you might want to put into a zero compression motor.

Yes, compression is good, haven’t done an actual test with gauge but got it to run last fall and I recently put a new head gasket on. Both cylinder walls and rings looked fine so I believe the compression is nothing to worry about. Thanks!
the ol thumb on spark plug hole showed compression as well, pretty decent too!

 

[Tim Frank]

"

Yes, compression is good, haven’t done an actual test with gauge ....so I believe the compression is nothing to worry about. Thanks!

"

OK....what I thought. You have NOT done compression test.
Your beliefs notwithstanding, compression is indeed something to worry about.
Especially if the engine does not currently start.

"

the ol thumb on spark plug hole showed compression as well, pretty decent too!

"

When was the last time you had your thumb re-calibrated? Thumbs are notoriously inaccurate in the range above 5 PSI.

The secret to effective troubleshooting is to work systematically and to use the correct tools. Then you know, rather than "believe" and have a true baseline rather than "pretty decent".

Just sayin'

 

[Crosbyman]

Thumbs are notoriously inaccurate in the range above 5 PSI.:thumb: :lol:​

 

[LargemouthBass21]

""

OK....what I thought. You have NOT done compression test.
Your beliefs notwithstanding, compression is indeed something to worry about.
Especially if the engine does not currently start.

""

When was the last time you had your thumb re-calibrated? Thumbs are notoriously inaccurate in the range above 5 PSI.

The secret to effective troubleshooting is to work systematically and to use the correct tools. Then you know, rather than "believe" and have a true baseline rather than "pretty decent".

Just sayin'

The reason the motor does not start is there isn't spark. I am replacing the coils soon

 

[LargemouthBass21]

""

OK....what I thought. You have NOT done compression test.
Your beliefs notwithstanding, compression is indeed something to worry about.
Especially if the engine does not currently start.

""

When was the last time you had your thumb re-calibrated? Thumbs are notoriously inaccurate in the range above 5 PSI.

The secret to effective troubleshooting is to work systematically and to use the correct tools. Then you know, rather than "believe" and have a true baseline rather than "pretty decent".

Just sayin'

after replacing the coils, and if I get spark and still can't start the motor, I will get a tester and check compression. I really reefed on those bolts and they are definitely over 7 ft/lb

 

[jimmbo]

Really reefing on bolts going into Aluminium is not the best idea. Many a Heli-Coil have sold because of that