Props, Props, Props

[THerbert]

Good morning everyone, I have a 2011, 20ft Maycraft CC w/ Yamaha 150F 4 stroke - Apollo Prop XHS # 993023 - 15 1/2" Dia / 17 pitch, that was supplyed with the boat when purchased (upgrade) Purchased the boat from Ed's Marine in VA (best price). I'm very happy with the boat and motor. with that said, when I took it in for service the the first year (ussually do my own servcie , but wanted a professional to cheack it out for the initall inspection) for routine maintenance and service, i asked the mechanc to check it for a rattle type noise and vibration at idle. I hear the noise at low idle in gear, drop it out of gear and it goes away. Mechanic said prop was the wrong one for the application and was out of round. The clearance is very close, but when you rotate the prop the blades run true. the the flare on the exhasust is slightly out of round and gives the impression of a wobble. I was going to go back to Ed's with the issue, but Michigan Wheel list this prop as an option for the 150F. Anyway at WOT the boat runs 42 mph @ 5100 - 5200 RPM. Any thoughts?

[99yam40]

Isn't the F150 upper range 6K

Might check hear to see what you should be getting and what prop they used on a set up close to yours. http://www.yamahaoutboards.com/owner...ance-bulletins

Believe I have heard that the heavy stainless props cause noise at idle in gear

The motors do not come with a prop, dealer puts on what is needed for the set up. deal with them on the prop

[cruiser54]

Hi therbert.

I have same motor and had similar problem.

First, Yamaha specify a wot rpm between 5000 and 6000, closer to 6000 the better.

With your prop I suggest that the prop is too big and heavy - you are experiencing PROP CHATTER. You will hear prop chatter at low rpm (<1200 rpm) and it will go away as you increase RPM. I would start off with the standard 17 inch painted black stainless steel Yamaha prop, I think it is 13 3/4 x 17 (17M). Apparently Yamaha suggest their Reliance prop for F150s, this being the case the 17 inch Reliance prop will suit. You will have to fiddle with props but I suggest go no higher than a 14 1/4 diametre. Your current 15 1/4 prop must be almost touching the trim tab anode! Motor height should also be checked

Cheers,
Cruise54
Australia.

[BaileysBoat]

Hi therbert.

I have same motor and had similar problem.

First, Yamaha specify a wot rpm between 5000 and 6000, closer to 6000 the better.

With your prop I suggest that the prop is too big and heavy - you are experiencing PROP CHATTER. You will hear prop chatter at low rpm (<1200 rpm) and it will go away as you increase RPM. I would start off with the standard 17 inch painted black stainless steel Yamaha prop, I think it is 13 3/4 x 17 (17M). Apparently Yamaha suggest their Reliance prop for F150s, this being the case the 17 inch Reliance prop will suit. You will have to fiddle with props but I suggest go no higher than a 14 1/4 diametre. Your current 15 1/4 prop must be almost touching the trim tab anode! Motor height should also be checked

Cheers,
Cruise54
Australia.

A lot of good advice in this thread. THerbert your numbers don't add up, getting negative slip with the rpm/speed readings. Are those GPS?

I am using the Yamaha 17P aluminum and get good performance, 44MPH plus.

[THerbert]

Thanks all, Yes it barely clears the Trim Tab Anode. I was pretty heavy the other day full tank of gas water in the live well cooler of iceup front. With a lighter load I have seen RPMS around 5400 and speeds around 44-45 mpg. Speedo and GPS track about the same at WOT. I agree with everyone about it being to big. Would like to get rid of the prop chatter. What else might I gain with a smaller dia.

[Sparkieboat]

I have heard of issues with 4 strokes if they are not propped for the upper rpm range, I would try a 15 on it, see if you can get it to 5800 or so.

[THerbert]

Prop Chatter

Reserched Yamahas performance bulletins for boats in my lenght/ beam / weight range and could not find one recomendation for 15 1/2" / 17 on a F150. Most popular was 14 1/4 / 17 and the next was 13 3/4" / 19. Also serched boards for prop chatter and the root cause is heavy SS props. Seriously looking to down size would like to see RPMS closer to max and get rid of prop chatter. Also would be nice to get rid of the clung going in gear. any thoughts?

[cruiser54]

Reserched Yamahas performance bulletins for boats in my lenght/ beam / weight range and could not find one recomendation for 15 1/2" / 17 on a F150. Most popular was 14 1/4 / 17 and the next was 13 3/4" / 19. Also serched boards for prop chatter and the root cause is heavy SS props. Seriously looking to down size would like to see RPMS closer to max and get rid of prop chatter. Also would be nice to get rid of the clung going in gear. any thoughts?

My initial prop which created a lot of prop chatter was about 15 1/4 x 17.
I replaced it with a 13 3/4 x 17 (Yamaha painted SS 17M) and the prop chatter went away. You will eliminate prop chatter by reducing prop size. As stated you may need to test different prop sizes to reach specified WOT rpm and eliminate the chatter.

The clunk/crunch/metallic sound when selecting gear (f&r) is another story.
All F150s do it. I have heard stories that by fitting a prop with a rubber bush may reduce the noise. Techs have told me by "swiftly" selecting gear reduces the noise and to make sure that idle rpm is set at the lower side of the spec (around 600 rpm). The noise is actually the dog clutch, quite normal but sounds ordinary. I did not investigate the rubber bush prop option, I have got used to it.

What makes it noticable for me is that my previous motor (Etec) did not have this issue. I think Yamaha have released a rubber bush prop that reduces/elimates the gear select noise but the prop is not suited to the F150.

Cheers,
Cruiser54

[THerbert]

Thanks Cruse54, I was leaning towards the 13 3/4 / 17. I'm going to speak with the dealer that sold me the boat and supplied the prop. Don't think it will make a diference been to long now (2yrs). Other than the prop chatter and not hitting peak RPM the boat performs well. I think if I lose anything it will be staying on top at lower RPMs. Something else to add to the neverending list.

[rodbolt17]

that prop chatter is rather inherent for a large bore 4cyl 4 stroke motor.
its caused by the acceleration the deceleration of the crankshaft at low speeds due to 1 cylinder fires and speeds the crank down then the next cylinder is coming up on tdc compression stroke and slowing the crank down.
this causes the pinion and fwd gears to speed up and slow down.
this causes the shift clutch and propshaft to speed up and slow down.
this causes the clutch dogs to move away from the gear dogs then the gear speds up and slaps the clutch again.
annoying but ok.
best prop I tried on my F150 also made the most noise at low speeds.
that F150 MUST be propped to run above 5700 RPM with the load THAT day.
yamaha released a series of SS props designed for the F150.

[BaileysBoat]

that prop chatter is rather inherent for a large bore 4cyl 4 stroke motor.
its caused by the acceleration the deceleration of the crankshaft at low speeds due to 1 cylinder fires and speeds the crank down then the next cylinder is coming up on tdc compression stroke and slowing the crank down.
this causes the pinion and fwd gears to speed up and slow down.
this causes the shift clutch and propshaft to speed up and slow down.
this causes the clutch dogs to move away from the gear dogs then the gear speds up and slaps the clutch again.
annoying but ok.
best prop I tried on my F150 also made the most noise at low speeds.
that F150 MUST be propped to run above 5700 RPM with the load THAT day.
yamaha released a series of SS props designed for the F150.

I finally heard why props chatter, thank you Rodbolt.

[rodbolt17]

stupidly simple aint it