Four blade prop

[zenoahphobic]

The above can be categorized as *****ing because the OP's thread has been hijacked. But I believe it is not *****ing because it is not malicious, it is not deliberately trying to attack or "set" anyone up; it is not argumentative, but it is arguing. All sorts of professions argue, it is part of their work: lawyers, scientists, polititions, researchers etc.etc. Arguing is good.

Things sometimes need to travel around a bit to get to the nubb.

The last point does start to bring it back to the OP, it is actually pertinent but way way out of the scope of the OP's question, again perhaps *****ing becoming self interest. But it is not malicious. To be called a ***** I regard as offensive, when it is used to be meant as derogatory as this term seems to have become.

[rodbolt17]

yall are all *****s.
I mean we all know aussie poppycorn cooks from the top down.
we all know that aussie toilets flush up.

we all know that 4 blade props are not as good as 5 or 6 blades

but at the end of the day four strokes tend to react worse if overpropped.

if you can find a prop shop or dealer that will let you try varios 350-550 dollar props, good on ya.

cause at the end of the day that's about all you can do for YOUR rig.

some years back I rigged and mounted a pair of F225TXRB motors on a 336 grady.
got the WOT RPM at 5900 RPM.
next year the guy was back, whining.

motors were mutts max RPM was about 4000 and its just not right and its still under warrenty.

I went mobile to the boat to address his issues.
yimminies.
he had added a full tower second station with curtains and a second station sunshade.

ya think it dropped the WOT RPM ?
propping aint black magic.
to get the absolute optimum for that INDIVIDUAL rig may take a lot of time and money.
most times its simply not worth it.

maybe tomorrow I will get my aussie built .303 enfield out .

[RayBersch]

if you can find a prop shop or dealer that will let you try varios 350-550 dollar props, good on ya.

You're hot on that one 'cause that's what I did but, um, the price was well north than that - BUT we worked together and got it right to both my satisfaction and the health of the motor.

Townsend - pass me a large bag please.

[TownsendsFJR1300]

Townsend - pass me a large bag please.

Here ya go, don't spill it!

I was fortunate enough when my boat was re-powered in '07, they obviously did NOT sea test it. It would barely hit 5,000 RPM.

I brought that aluminum prop to my local prop shop, told them what it was doing and bought a SS prop (not a Yamaha-but still a 3 blade) different pitch, etc.

Brought the engine RPM's up to 5,800-5,900 depending on the trim.

A entirely different engine with the correct prop. It'd jump out of the hole now and comparably to my old 150 V6 Evinrude..

[dngharvey]

I think I like it!

Found a like new Solas alum four blade 13 X 15 for $75 bucks. Replaced a 13 X 17 three blade SS.
Top speed WOT with 3 blade was 5800 at 40 mph
4 5600 at 38 mph
Min planing with 3 was 3200 at 17 mph
4 2900 at 15.5
Above are half tank and just my 260#

With four full size adults and three kids, 5400 WOT/ 3100 at 16 mph. Need those tabs with the load to hold plane, though.

I did not check time to plane but was very pleased with the way she climbed over the bow wave when loaded heavy. I hope and believe I hit real close with the first change out.

Hope this helps some along the way somewhere, guess you really don't know till you try.
Having said all this, I have thoroughly enjoyed the back and forth on this thread, Rodbolt never fails to entertain with his vast knowledge and quick wit and I'm sure he knows he is appreciated here!

[RayBersch]

Well, that's absolutely wonderful and contrary to what I would have thought based upon my experience. I accomplished a lower plane speed but not a faster time to plane (hole shot) so I figured you would find the same but be dissatisfied with the results. So the most important thing is that you are happy with with results, and you certainly spent a whole hell of a lot less than I - but then, I was playing with a stainless prop.

Great job and thanks for the followup - now I will save the popcorn for later tonight when I watch a movie.

[TownsendsFJR1300]

I'm sure you already know, but especially with a heavy load, moving some folks (weight) forward (especially when accelerating) should make a bit a difference planing out..

Glad you close / happy with the outcome..

Now to find another thread to finish my popcorn!

[dngharvey]

Even more pleasant results

Took another group of adults, five this time, and found I can use a lot more trim before cavitation sets in. Also tried getting on plane without the tabs and glory be, she popped right up! Bow definitely stays down a lot more. That must be the "lift" everyone references.
I'm happy.

[zenoahphobic]

Took another group of adults, five this time, and found I can use a lot more trim before cavitation sets in. Also tried getting on plane without the tabs and glory be, she popped right up! Bow definitely stays down a lot more. That must be the "lift" everyone references.
I'm happy.

I'm glad that this thread ended with your results as positive and informative. Still puzzled about why the "expert" advised against a four blade; as I don't think there is enough anecdotal evidence out there. Well done.

[boscoe99]

I'm glad that this thread ended with your results as positive and informative. Still puzzled about why the "expert" advised against a four blade; as I don't think there is enough anecdotal evidence out there. Well done.

So called "experts" advise all of the time but most of the time it is pure speculation. It might be based on what worked before, but which won't necessarily work in a different application.

There are some very general guidelines that can be followed with propping a motor. My experience indicates that at the end of the day a number of propellers have to be tested to determine the best fit. Each boat and motor configuration is different and what one fellow wants out of a propeller can be completely different from what another fellow wants, even if it is on the same boat and motor.

Propellers seem to be the number one item where people want "silver" bullets given to them in the form of the brand, model and exact pitch that they should be using. Does not work. It takes testing. And money. Money and time folks don't want to spend.

Oh, let's not forget about engine height and trim angle. Which will affect a propellers performance.

[zenoahphobic]

And what is interesting that Dngharvey got less slip (greater grip) and comparable revs per speed with an aluminium four blade to his original SS prop.

Makes you think if you could get that Solas at 14 pitch, his revs will meet 40 mph he originally had but better planning characteristics !

[almetelo]

There are some very general guidelines that can be followed with propping a motor. My experience indicates that at the end of the day a number of propellers have to be tested to determine the best fit. Each boat and motor configuration is different and what one fellow wants out of a propeller can be completely different from what another fellow wants, even if it is on the same boat and motor.
.

Most of us when propping a motor think mainly on the pitch but is much more than that...

On my buddy Yamaha 50 2strk we tested 3 diferent ALU 13 pitch props and we had 3 completely diferent results.

Yamaha 10-3/8 13 , Yamaha 11-1/4 13 and Honda 11-1/8 13

He ended buying the Honda prop which was the best for his application while on my Skiff/F40 Yamaha 11-1/4 13 was the best option on the 13 pitch range.
I'm using a Yamaha 11-1/4 14 (5800rpm's WOT with usually load) but next week will test a 11X15 prop.

As Boscoe mentioned best thing is test the propellers but that requires have some loan props or spend some money.