new 4 blade SS went worse then my 3 blade al prop :S

[Markov1985]

Hey guys, I made the change on my 5.7ltr four winns H190 from a 19 pitch 3 blade aluminium prop (which was pretty banged up) to a brand new 17 pitch SS 4 blade prop. Straight from the word go, it went like a pig. lot slower (top end i expected but its like 10mph less) and it now turns like the titanic and engine revs less. I put the old prop back on while still at the lake, hard turning is back and speed and engine sounds better (more rpm). My volvo penta already seemed too quiet for a v8 since i purchased it, but with the new prop, it just feels sluggish n engine isnt reving as much. 2 pitch down u expect revs not to drop :S

 

[Markov1985]

Re: new 4 blade SS went worse then my 3 blade al prop :S

p.s. new prop is a power tech ELE4R17MS275

 

[Bifflefan]

Re: new 4 blade SS went worse then my 3 blade al prop :S

Speaking only to the prop, it sounds to me like it did exactly what I would have expected.
If you were good with a 3 blade, why go to a four? All be it that the 3 blade was banged up. A "banged up" prop will usually give a higher RPM, because it has less grip on the water, thus more slip.
Adding one blade gives you about 25% more grip on the water, then going from a "not perfect prop" to a new one will add (lets say) another 25% grip. Now you increased your prop bit by 50% over the bad 3 blade. Of couse things are going to change. RPM drop and so on. Plus a 4 blade will normally turn harder than a 3.
Now, with a 5.7 in a 19 foot boat, I would think a 23p prop should work, so if you cant push a 17 4 blade (close to an 18 3 blade), then I think you may some other issues that need addressed.
Also remember that the less hull in the water, the less it will turn. A 4 blade will tend to have more bow rise, try trimming in when you turn.

As for the sound of the motor, if you want it louder, go with thru hull exhaust. That will be plenty loud, I would use cut outs so you can change it back to normal when you want to. Keeps the DNR off your back.

 

[Dhadley]

Re: new 4 blade SS went worse then my 3 blade al prop :S

Sort of hard to figure out what's going on without some specific numbers - true speed, true rpm and gear ratio. We'll assume the motor is running correctly although that needs to be confirmed. If the 4 blade prop you went with was not designed specificaly for a sterndrive that will be a factor also.

 

[NHGuy]

Re: new 4 blade SS went worse then my 3 blade al prop :S

I agree with Biff. In fact I have a 19 footer that runs a 23 pitch 3 blade. It's a vee hull with 21 degrees of deadrise and weighs about 25 or 2600 lbs. It will run to redline with 4 people in it.
How is your engine running? Bottom clean? Do you carry a lot of weight?

 

[Markov1985]

Re: new 4 blade SS went worse then my 3 blade al prop :S

thanks guys

Well the old prop took too long to bring bow down, and i use it for wakeboarding with 5-6 adults in boat at any one time. 3-4 prop shops here in aus recommended a 17 pitch 4 blade SS prop for my application and same was recommended from the american stores, All said improve your hole shot and low end power, losing some top end, but i didnt really mind loosing top end.
Shame though, waste of 500 bux if i cant sort it out somhow :S

 

[Robbabob]

Re: new 4 blade SS went worse then my 3 blade al prop :S

Only thing nobody knew, was how badly damaged the old prop was. Slip was obviously worse than you thought. Going from a good 19p 3-blade to a good 17" 4-blade would have worked just as everyone stated.

Without getting into changing gears (not sayin' you should), not sure what you can do to "sort it out". What are the specifications with the new 4-blade (new max rpm at WOT, etc.)?

Good Luck!

 

[Markov1985]

Re: new 4 blade SS went worse then my 3 blade al prop :S

hrmmm in not really sure what to say about the rpm, my rpm guage doesnt work :S just my speed, fuel, voltage etc, everything but the rpm. So i was going just from feeling n engine sound. i just know the engine sounds like its reving harder with the 19 pitch 3 blade al prop and is able to turn boat much more sharp etc. the 17pitch ss four blade lays the boat on its side, taking a much larger circle to turn around, engine just doesnt sound like its working as hard, and you can feel the difference is no good

 

[Riegfrghtl]

Re: new 4 blade SS went worse then my 3 blade al prop :S

I first would get rpm gauge fixed or replaced. Find max rpm and speed (by gps) for the 3 blade and then the 4 blade. Compare your max rpm's of both props with what the manufacturer max rpms for your motor. Then you will have some baselines to work with. Your props need to turn as close as possible to the high side of man. max rpms. You will also be able to narrow down problem to motor, boat, or wrong prop.

 

[Tail_Gunner]

Re: new 4 blade SS went worse then my 3 blade al prop :S

hrmmm in not really sure what to say about the rpm, my rpm guage doesnt work :S just my speed, fuel, voltage etc, everything but the rpm. So i was going just from feeling n engine sound. i just know the engine sounds like its reving harder with the 19 pitch 3 blade al prop and is able to turn boat much more sharp etc. the 17pitch ss four blade lays the boat on its side, taking a much larger circle to turn around, engine just doesnt sound like its working as hard, and you can feel the difference is no good

Info is vital in making a prop selection from a laptop or home computer. Wiht that said is this boat new to you???? I know this may sound incredible but people do not always take care of there boats properly hmmm cars to..

The fact the tach is not running may indicate maybe theres been some negelct. Are you capable of tuning or checking the engine by your self....do you have access to a freind who can help.....I boats is a treasure trove of DIY boating....About the only thing that is not disscussed is building boats from the ground up....Now some have cut there boats in half and extended it a bit...Truly a amazing thread....Tinkering at its finest..

Check the engine to make sure its tuned...plugs wires caps.. a 17p 4 blade sounds right dont be so quick to assume you have wiffed 500 scoots..it may be just bad plugs or wires

Here are some good points...take the time to follow them as close as you can it can be a real adventure.



When posting a question about propellers, you cannot get a reasonable answer unless you provide the following information in your post: Items 1-4 are essential for meaningful response to most questions.
1) Performance issue you are trying to correct.
2) Current prop manufacturer, model, aluminum or stainless as a minimum.
3) Current prop diameter and pitch (required).
4) Wide open throttle RPM and speed with an average load (very helpful)
5) Engine/drive make, model, year, and HP
6) Boat make model, year, length and weight

 

[Markov1985]

Re: new 4 blade SS went worse then my 3 blade al prop :S

Guys just a follow up on outcome for this thread i started a while ago and finally got test results. In the end the situation was the 4 blade SS was overall winner for my situation.
The two props I compared were my original OMC 19 pitch alumminium 3 blade prop (which I just had complete recondition at prop shop 2 weeks ago) and my PowerTech "E" Series SS 4 Blade(ELE4R17SM275) 17 pitch which i originally had issues with but had thrust bearing slightly machined so prop sat closer to boat (originally sat out a bit further then my 3 blade prop). Boat is a 97 fourwinns H190, 270hp 5.7 litre volvo penta sterndrive sx, weight approx 1800kg i think, 19ft.
Tested on wide, deep river, flat like glass, 8am, no wind, both props maxed out at 4500RPM, Both seemed to turn about the same, though i noticed the 3 blade tended to slip for a bit then grip quickly if i made a real sharp turn at higher speed where the 4 blade kept traction (im refering to 20-25mph then yanking that sterring wheel pretty sharp). The 3 blade was approx 3 mph quicker according to speed tach, but the 4 blade most noticable difference was its hole shot.... if i jammed throttle to like 1/2 or more, the boat would leap out of the water like a frog on heat, the 3 blade planed pretty quick aswel, but didnt "jump" out of the water. Later that afternoon, i had friends tubing off the back using the 4 blade SS, and 5 people in the boat, she still leaped out of the water ( i didnt do this test with passengers with the 3 blade though)

Hope this helps anyone else whos in similar situation

 

[steelespike]

Re: new 4 blade SS went worse then my 3 blade al prop :S

Nice to see you got things straightened out.Thats what a 4 blade is supposed to do.

 

[Tail_Gunner]

Re: new 4 blade SS went worse then my 3 blade al prop :S

Id still have the engine tuned by a pro....maybe a car mech not marine..sorry to say that but it is what it is..4500 is not prime time for a 5.7 more like 48-5000 a side bar here...lugging a motor is not good ...Now lugging a drive is worse.

 

[Markov1985]

Re: new 4 blade SS went worse then my 3 blade al prop :S

Id still have the engine tuned by a pro....maybe a car mech not marine..sorry to say that but it is what it is..4500 is not prime time for a 5.7 more like 48-5000 a side bar here...lugging a motor is not good ...Now lugging a drive is worse.

IN my volvo owner manual, it says WOT for my engine 1997 Carbie 5.7GS is 4400-4800rpm. So I can increase the rpm by tuning engine, not only changing props? So you recommend getting her to run at the 4800rpm mark? will the extra 300rpm make a noticable difference to motor except taking in more fuel i assume?

 

[Tail_Gunner]

Re: new 4 blade SS went worse then my 3 blade al prop :S

Well in a word yes to all, Heres the issue or maybe not....As i understand your boat is a 19' boat with a 5.7 liter motor .....270 hp.

Engine Specifications

Quantity: 1
Horse Power: 250
Type: Gasoline
Hull Material

Fiberglass
Beam

7'0"......
Net Weight

2430...............


The fact that you had mech issues with the prop......Its a light weight and narrow boat....it has 270hp and a lot of tourqe for that boat turning a 17 @ 4500 is suspect. Actually that boat should be a 60mph boat with people. But sitting here and your there its hard to be sure. A tune up should be looked at if you have not done so in 3 yrs

 

[Markov1985]

Re: new 4 blade SS went worse then my 3 blade al prop :S

Hrmmm, well i purchased the boat only 2.5 months ago, used it 3 times so far. Had electrical issue last outing but fixed that, boat lived in sydney, australia before i purchased it on the salt water, and judging from stickers i have found around boat, also lived in las vegas, USA. so alot of the connectors have corrosion. im just trying to think if it would be more of a engine issue or transmission issue if im losing this speed/rpm. You are right btw, im reading here that the 4.3ltr model in same hull has top speed range of 48-50mph, and im doing about 38mph with 17p SS 4 blade and 40mph with my 19 pitch aluminium 3 blade. P.S. I played around with the trim while doing thiis WOT test, incase anyone reading this assumes i didnt have trim set correct

 

[Tail_Gunner]

Re: new 4 blade SS went worse then my 3 blade al prop :S

A tune up is really a simple thing..Its just plugs..wires...Ohhh and that big carb thing... But any compent mech can do that. A carbed 5.7 really is very simple...Can you change plugs and wires....maybe get a good moblie tech to come out and check or clean the carb and timing...i cant be sure but it really sounds like there are some issues...A good spary and clean with WD-40 will clean up a lot of corrison.

The I/O forums are a great place for information and some of the best mechs you will come across.