five blade props

[jekyl]

I have been considering new props as my current Yamaha 17" pitch x 15 1/4" diam won't allow my 200hpdi's to rev out to 5600 lightly loaded. Max revs is 5300rpm.
I have been getting quotes from the US as props are exorbitant here in OZ.
Has anyone got anything good or bad to say about Hill propellors. specifically their 5 blade which is what has been recomended by their people?

 

[ocnslr]

Is that 5300 WOT with the engines trimmed out until just before the props ventilate?

Are you comfortable with the engine mounting height? Most manufacturers and dealers tend to mount them too low, to avoid complaints about blow-out in turns.

I have no experience with five-blade props on outboards (on Spruance class destroyers....), but my gut reaction is "no-way". Have also never heard of the props you mention, and I have read a LOT about propping boats.

I have had great success with PowerTech props. When we had the single 250HP OX66 on our Islander I did a lot of prop evaluation, and eventually went with a four blade - the OFS4-17. We had been running the 15.25x17" SWS prop, and were still able to make RPMs at WOT with the four-blade PT props.

We've had the F150s for over three years (735 hours) and were running the recommended "Black SS" 13.75x17". Tried several alternates, and went with PowerTech OFS series again. This time in 16" pitch, with some cup added by the local prop shop.

Brian

 

[Curmudgeon]

Put a stock 15" on it and don't look back. Should also get you closer to max (optimum) when loaded, too ... :wink:

 

[gradyfish22]

I'd avoid a 5 blade personally, you will likely have similar blade area if it is a good prop design, but typically the more blades the slower you go, sometimes they are better on fuel to a point, but typically not, I would think a 5 blade would be a horrible choice for your engines. I think you would be better off sticking with a 3 bleade, 4 blade max is warranted. You would do better getting a propeller with the right diameter and pitch.

 

[jekyl]

Thanks guys for the valuable feedback. Interesting none of you have heard of these guys, on the net of course.......
Brian what differences did you note with the 4 blades on the 150's, compared to the 3 blades.

 

[Little Buddy]

Hill Propellers

If this is Hill Propellers form Santa Ana California on the west coast, then I would tend to believe what they tell you. I've used them in the past when I use to take my old boat to the river and tear up props. I forget the main guys name but he new his stuff. I'd go in and tell him what I wanted the boat to do and he'd recommend a prop. He was right on all the time. If you give him all the correct information about what your boat currently does and tell him what you want it to do, you should be okay. As for 5 blade props, I have no experience. He had me switch from a 3 blade to a 4 blade on my 150 Merc and it fixed my hole shot and top end rpm.

 

[Grog]

5 blade? I don't see what that's going to do for you that a 4 blade wouldn't. There's more leading edge for more drag which will hurt max RPM.

If I buy another set of props they will be Mercury.

 

[gradyfish22]

I agree with Grog, the 5's will hurt you, they might seem better since they would have a better pitch and diameter ratio to suit your bot better, so it might seem better then what you have now, but really it will be worse then what you could have with less blades. We go to more blades qwhere I work for less vibration in the cockpit, but we lose speed while maintaining the same rpm between the two. We see similar low to mid range numbers but lower top end and usually more fuel burn for the midrange rpm's with more blades. Sometimes, a 4 blade can be very close in results to a 3, but a 5 is a bad choice for a boat your size, I think it will fall flat on its face when heavily loaded and not have the power to stay on plane well in rough seas at slower speeds.

I too will go to Merc props if/when I replace my current Yamaha's. A lot of guys have had great results going to a Merc prop on the Yamah's. Yamaha props are just ok, Merc does make a better prop.

 

[ocnslr]

Brian what differences did you note with the 4 blades on the 150's, compared to the 3 blades.

Didn't go to four blade on the F150. Went from Yamaha Black SS props in 13.75"x17" to PowerTech polished SS OFS3, in 15.25"x16", with additional cup added. Could probably have swung the PT props in 17", as I could hit the rev limiters on the 16" before the cup was added.

The PT props have given us a broad range of improvement from the Black SS, primarily due to more diameter = more blade area.

We went from a Yamaha SWS 3-blade to a PT OFS4 prop when we had the single 250HP OX-66. It stayed hooked up much better in sloppy seas, gave improved performance in the low and mid-range, with only slight loss of top end speed.

For what it's worth, my (trusted) prop guru says that the Yamaha SWS props are extremely well designed and, while he can usually improve hole shot OR mid-range OR top-end, it is difficult to find a better prop across the entire range.

Still have those questions re engine trim at WOT and mounting height.

Brian

 

[JUST-IN-TIME]

5 blade is for tow sports
4 blade hole shot cruise
3 blade top speed

 

[jekyl]

Great info thanks guys. I am absorbing it all . Sounds like 5 is out of the question.
Interestingly merc recomended their Inertia 3 blade I think.

Lots of you say Merc and I have heard that here as well.

Brian I had the motors trimmed out as far as I would ever have .
Looking at the cav plate it is still just under the water which makes me think I could go one hole higher. I may try it next time the boat is in the shop for a service. To big a job for me. The props never let go normally only when coming off plane quickly and they have been trimmed for cruise.