Piranha Composite Propellers

I have a llot of info on these, DoD, and some good suggestions. But you done scared me off I am staying out of it.........
 
I had a comprop on my 70 eveinrude and loved it. so i tryed one on my honda 90 and found that it flexed to much trying to get no plane. I really loved the 4 blade props so i ended up going with a alum 4 blade by solas. That has the advantages of a four blade and the stiffness of a alum prop. the cost was low too.
 
DoD - I've been thinking about trying the Piranha prop for a while, but just haven't gotten to the buying stage.

From what I read, they recommend their SB-4 hub together with their A-4 blade to get the full 14" diameter Suzuki permits. sounds like a pretty good solution to me ... I just haven't given it a try yet.

I've been using a ProPulse 4-blade for a couple years (have tried 17, 18, and 20 pitch). I don't haven any complaint with ProPulse, but would like to try something that permits the full diameter. My ultimate objective is to find something that will let me get closer to 4mpg with the Suzuki 90 at cruise (about 4200rpm).

Let me know if you go for the Piranha.

Casey
C-Dory Naknek
 
I have been told the Suzuki and Johnson 90 are the same motor and they look identical. Is the lower end and the gearing the same?

I bought a propulse 4 blade for the Johnson but it is too small. Got a deal at the WM discount area so I can't take it back.

I would like to try another 4 blade though.
Steve
 
Steve,

As far as I know the Johnson and Suzuki are exactly the same, (including the gearing) just different decals and paint.

Like you, I have the ProPulse. Best pitch setting seems to be 17inches. As mentioned earlier, I am not dissatisfied with the Propulse, but would like to maximize performance (and hopefully get a slight mileage increase in the process).

Since it sounds like you and Dan (and others maybe...) have Suzuki/Johnson's we might want to compare notes. I have a couple of spreadsheets with performance data I've collected that plot speed and fuel mileage with the ProPulse and the original Suzuki prop (14" x 17P x 3). If you want the spreadsheet drop me a note at: lorencasebeer@aol.com

Casey
C-Dory Naknek
 
Wow that is an interesting prop DoD, I will be very curious to see how it does.

The prop on my Suzuki 90 is looks huge already and I dont have the math savy to work out all the pitch and diameter variables so for those of us mathematically challenged..your leading the way!
 
My question for some of you smarter folks than me out there is going from a three blade to a four blade prop should the pitch remain the same? I'm presently running a 14 dia x 15 pitch on my etec. I do have a propulse that is left over from my previous motor that will fit. The pitch range however is 16-20 and it is only 13" dia. the pirahna however does one in both a 14x15 and a 14x13. I will give the propulse a try when I get the chance but will I be losing something by going to the decreased dia? Thanks in advance.
Norm
 
Norm-

Sorry the gang didn't pick up on your question earlier!

Dan has given you the straight story about what can be expected in your situation.

The only thing left to do is to mount it up, give it a spin, and see what happens!

It seems that we have some some foot dragging on making predicions about props these days.

That's because nothing seems less predictable than propeller performance.

Too many variables and unaccounted for performance details.

Stick your neck out and those prop blades will get you every time!

Not to worry, just give the other prop the whirl and give us the straight spin on what you get.

Joe.
 
this is all very technical to a noobie. :disgust I'm reading with interest, since the honda 90 I'm looking at buying has no screw attached. Now I get a chance to try understanding metal vs plastic or something, 3 vs 4 blades (unless Beaver Cleaver designs it), diameters and effective blade area, pitch . . . hubs . . . yikes! :smileo

Assuming I don't know how any of these materials, designs, or screw geometries translate to speed, economy, and engine life, and assuming I want the potential to push my 22' classic at a max speed of about 30knots light (no, I don't generally drive it there), and a probable cruise speed of 13-15 or thereabouts loaded, and get the best economy and life out of this honda 90, and assuming I'm gonna run over kelp with it, can one of you more-smarter-than-me guys make a recommendation for a starter prop? What would I expect to pay for one? Is it safe to buy a used one? Does it help to wax it?

Maybe I need more coffee?

:roll:

Thanks in advance!

rooter
 
computer-rooter

Short answer-

!.) Basic prop: OEM Solas 3 blade aluminum. 15 inch pitch, about 13.5 to 13.75" diameter.

2.) Eliminate the first step and go directly to Solas 4 blade, 15 inch pitch, 13 inch diameter aluminum Amita prop- this is the best all around prop for this engine on a C-Dory, and probably is especially true considering the flat bottom of the Classic 22.

3.) Read endless prop discussions archived here, on other boating groups, and elsewhere in the known and unknown Universe. Come to same conclusions as above. Start over with #1 and proceed to #2.

4.) Don't like your results? Don't blame me! I've got a Yamaha! Instead complain to dogon dory Dan, a Suzuki guy ! Then find a Honda guy and chew him out good for not answering your questions.

5.) Drink six more cups of coffee and return to #3. Take the reading materials to the bathroom since you'll be spending most of the evening there.

6.) Look for used props on ebay. You can find the 3 blade OEM ones for about 1/2 price. Be sure to ask if they're dinged, like this post. You won't likely find the 4 blade Solas Amita there. Too prized to sell.

7.) Now get out the wax for your new prop. It MIGHT make it FASTER, or i t MIGHT make it SLOWER. Some offshore racers actually minutely rough up the back side of their props to get more grip (!!!) Go figure. Prop theory again. Skull it though all you want to and you still have a 70% chance of being wrong somewhere. Have several more of cups of coffee. It's gonna be a long night.

Joe.
 
Joe,

Very good reply!

Like DoD and others, I wish there was a more definite answer regarding the "which-is-the-best-prop-for-my-situation" question. But there are just SO many variables, it seems to take endless experimentation.

I guess you could say it's a fluid situation. (...er, er, er)

Just when you think you've arrived at prop-nirvana the paramaters change. ...you change the load/altitude/trim, etc. You collect all your performance data in fresh water - then go on a saltwater trip. Whatever.

But all-in-all, for some of us it's the fun of being anally retentive geeks trying to maximize the performance of our little adventure machines. Years ago we used to talk about how to get the best performance out of our prized 289/327/409cid engines; seems like yesterday. ...but it's still fun eh?

Maybe we should begin a thread on how to maximize C-Dory performance using a 10-20hp outboard! With the way gas prices are going we'll be there before we know it.

Anyway - thanks again for putting the prop variables in perspective!

Casey
C-Dory Naknek[/i]
 
Luckly for me, I know that there is no end to some debates, and some, like spark plugs and motor oil, shouldn't be engaged in at all. :) I'd been reading pitches everywhere from 12" to 18", diameters of nearly the same range, etc. My local marine shop suggested a 16-pitch. The guys at the dock got into heated arguments about whether the 13.131214 3-blade was more efficient than the 13.545 4-blade, between 2100rpm and 2600rpm, except on Saturday, when they load up on halibut. I have no illusions about attaining perfection on my first experiment, I just needed a reasonable baseline to start chucking props at, since I had nothing at all and no clues.

The consensus seems to be the aluminum, 4-blade 14 or 15-pitch on a 13" diameter. Since the pitch seems to be the "final drive gearing" part of the equation, I'm going to start with the taller gear and try the 15-pitch. I'm prepared to make adjustments up or down from there.

Also, while studying up on shaft length and such, I got a close look at my existing prop on the suzuki 100 and discovered a ding in a blade. I don't remember striking anything, but one leading edge is definitely curled. Can I pound that flat again, does it need to see the doctor, or has this prop been ruined? Is it damaging something to run it like that? I do notice a little vibration in my feet at cruise revs.
 
computer-rooter

Standard fun tools for prop repair:

Vice
Big block of soft wood
big hammer- leather, wood, or rubber
series of files of increasing fineness
sandpaper-varing from about 120-400
black or while paint to hide what's left

You might have to take some off the other three blades to keep it balanced if it's really dinged.

About the only thing you can't do is weld it, unless you have the equipment.

Have fun!

Joe.
 
Sea Wolf":3drhruv7 said:
computer-rooter

Standard fun tools for prop repair:

Vice
Big block of soft wood
big hammer- leather, wood, or rubber
series of files of increasing fineness
sandpaper-varing from about 120-400
black or while paint to hide what's left


Joe.

Yeah, I got all that and I see where it's headed. But -- can anything be fixed without a sawzall and duc tape?

This is just a little curl on the edge of one blade. I think I can hammer it flat and file it smooth without losing more than a few grams of metal.

Finally -- if I go ahead with my choice of new prop, is there interchangeability between the suzuki 100 2-stroke and the honda 90? In other words -- could I replace it on the suzuki and then move it to the honda if I buy the honda, or are hubs or something different? Both engines seem to have the same basic RPM range . . .
 
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