Prop options

[silverbullet]

My stock VP prop was an alum 3 blade 14.25x21, on a Regal 2000 5.0GXI/sx 1.6 ratio.
Subjectively, it was a dog out of the hole, though midrange punch was good and top end was 54 on gps with a couple more likely to be had. Neglected to check top speed RPM- DOH! Seemed over propped in general.
In an attempt to get some bottom end, I got a VP alum 4 blade19x14. Now its great out of the hole, planes much quicker, great midrange, top speed 50 @ 5000 rpm, no more to be had. Oddly, at idle rpm, it goes faster through idle zones... efficiency?

Question is- what might be a good option to regain some top end without loosing holeshot and planning and maybe drop 200 rpm? SS 3 blade 21p? Alum 4 blade 21p? Would these two options perform equally except for strength?

Lastly, in trying out this new 4 blade over about 15 hrs run time it flaked off some paint off of the tips of a few blades in a very irregular pattern about 1" square- not as with wear/abrasion or impact (though there were a couple of small nicks on the leading edge...)

Question- could the wifes over-trimming while doing about 30 mph to the point of a few seconds of ventilation and increased rpms "vibrate" the paint off by harmonics? Or is it more likely factory paint defect?

 

[steelespike]

Re: Prop options

Not an expert but::I wouldn't worry about the paint though it may indicate a remanufactured prop.generally speaking a 4 blade will help low end performance but cost a little top end.Those nicks could be cause for a prop that isn't up to top performance.Was the prop new?Without your max rpm with original prop it is difficult to know where you were at.It would be good to have those figures.Usually a 2 inch change in pitch will result in 300 to 400 change in rpm.Going up to a 4 blade might temper that some.
If your boat had a dog hole shot but was reaching max rpm then something
was up.Did you trim in for hole shot?

 

[TilliamWe]

Re: Prop options

Try a 4 blade 20 pitch prop next. Good luck

 

[silverbullet]

Re: Prop options

Steelespike- the four blade was new in the box. I always have the trim fully down when standing start and trim up. Yea, I know I need to get my original prop back on for an RPM check at WOT.

In theory, since I don't have that number, if I were to get say 4800 rpm with the 3 blade 21 (dog holeshot), should I expect rpms higher or lower or same than that with the 21 4 blade?
The reason I mentioned 21 is I'm kinda inclined to stay with OEM unless I get get good reputable recommendations on an aftermaket prop company that's been around a while, especially if going to say a 20 p. Suggestions??

Does stainless hold any performance advantages or disadvantages for me and my situation and dimensions? SS 4 blade?

 

[Tail_Gunner]

Re: Prop options

My stock VP prop was an alum 3 blade 14.25x21, on a Regal 2000 5.0GXI/sx 1.6 ratio.
Subjectively, it was a dog out of the hole, though midrange punch was good and top end was 54 on gps with a couple more likely to be had. Neglected to check top speed RPM- DOH! Seemed over propped in general.
In an attempt to get some bottom end, I got a VP alum 4 blade19x14. Now its great out of the hole, planes much quicker, great midrange, top speed 50 @ 5000 rpm, no more to be had. Oddly, at idle rpm, it goes faster through idle zones... efficiency?

Question is- what might be a good option to regain some top end without loosing holeshot and planning and maybe drop 200 rpm? SS 3 blade 21p? Alum 4 blade 21p? Would these two options perform equally except for strength?

Lastly, in trying out this new 4 blade over about 15 hrs run time it flaked off some paint off of the tips of a few blades in a very irregular pattern about 1" square- not as with wear/abrasion or impact (though there were a couple of small nicks on the leading edge...)

Question- could the wifes over-trimming while doing about 30 mph to the point of a few seconds of ventilation and increased rpms "vibrate" the paint off by harmonics? Or is it more likely factory paint defect?

OK 3 blade alum 21p is doing 54 mph @ unknown rpm
4 blade 19 is doing 50 mph @ 5000
The 3blade 21 is probably doing 4800 (guess work)

That give's the 19p 4 blade 11% slip which is good
And the 21p 3blade doing 11% slip @ 4900 using the same slip ratio

Some ideal's......... it seems your stuck right in the middle here, aka 3 blades come in 17,19,21 odd number's and 4 blades do even number's...and then i look at your spec's where the heck did you get a 19 pitch 4 blade are you sure of that???/

Ahh Volvo of course... Serious question when your at wot with the 19p four blade do you or can you remeber ever hearing a ever so slight of a miss from the motor, it last's just millesecond's

 

[silverbullet]

Re: Prop options

Tail gunner- no missing at WOT-very steady and solid and stuck at 5000. Also that would surely freak me right out until I figured it was the rev limiter? ( I vividly remember in 1989 my 240 SX Nissan doing that @ 110?mph scared the poop out of me....thought I blew the engine.....really more of a speed limiter that cut out the ignition completely for a few seconds!)
There is however a cyclical/harmonics like vibration at many speeds that subtly vibrates the hull say every 4-7 seconds and a very shudder only when adjusting trim and at heavier throttle loads....FWIW.

Any suggestions on 20 p 4 blade prop manufacturer if it comes to that? (Plan is to keep the 4bl 19 as spare/tow day and e bay the 3bl 21).

 

[Tail_Gunner]

Re: Prop options

Best overall performer: http://www.iboats.com/mall/propfind...id=645&**********=559343248&*******=332123010


Probably best topend: http://www.iboats.com/mall/propfind...7117=1&**********=314110523&*******=884720447

Or a Merc enertia 20p 3blade top speed good grip and should drive it the fastest........but spendy

The Stilletto BayPro 11's just have to much cupping, a 20p will act like a 21 and a 18 will give you great midrange and hole shot but id bet youd only do 51.....You could alway's see if they will let you start with a 20 and go to a 18 but the michigan was reviewed by WH as a good prop and should outrun the 19 and keep you in the rpm range

 

[silverbullet]

Re: Prop options

Tail_gunner- that MW looks very interesting. I'm thinking that being 4blade my bottom end will still be good and the pitch will help the top end.

A merc prop on a VP? Won't I get some sort of matter-antimatter/oil-water/ice cream-jalapeno type reaction?

Thanks for your help.

 

[Tail_Gunner]

Re: Prop options

The merc Enertia is a intresting prop, from what i have gleaned, you need to keep it above 4900 rpm and then it does very well, under that and it's just another prop and for it's price.........who care's.

One thing that bother's me is the volvo prop, on my I/O it was a very poor prop and doing 50 with a four blade @ 5000 show's as much. I had a 3 blade 19 volvo that did 50 but the boat could hit the rev limiter ever so often. I put a 4 blade stilleto on it and gained 5 mph and a lot of other good thing's

 

[silverbullet]

Re: Prop options

Is that 4 blade stilletto you're referring to the Bay Pro II 14.25 x20 (with too much cupping)? Are you thinking that it( as a result of the cupping) would be too much prop/drop the R's too much?

 

[Tail_Gunner]

Re: Prop options

Yes the baypro'shave a lot of cupping, so much so that when measuring slip on 18.6 boat it reads 4%. The boat is a bow rider with a 20 degree hull and 2800 lbs, nothing special as far as fast hull design's. WH told me that if id used a 21p (prop calc) i would get a more reasonable slip which was 9%

In additon i ran a 3 blade stilletto in a 21p which gave me the same slip ratio of 9% and a 1 mph gain, but the lift the baypro's gave and the smoothness of there operation outweighed the top end, so that is where i stayed.

There have been a few member's here who have used those prop's with 20+ foot boat's and 5.0 w/efi both ended up with 18's. Another example of how much grip they have is RC Contruction's boat. We have indentical boat's and drive's but one diff. He has a 5.7 4bl with 300+hp and while he can swing a 22 to 4800 @ 60 i can only swing the same 22 to 4200 @ 53 with a 220 hp 4.3 efi v6........i would need 75 more pony's to get her up to speed and that's only a two inches of pitch.

 

[ron7000]

Re: Prop options

Yes the baypro'shave a lot of cupping, so much so that when measuring slip on 18.6 boat it reads 4%. The boat is a bow rider with a 20 degree hull and 2800 lbs, nothing special as far as fast hull design's. WH told me that if id used a 21p (prop calc) i would get a more reasonable slip which was 9%

In additon i ran a 3 blade stilletto in a 21p which gave me the same slip ratio of 9% and a 1 mph gain, but the lift the baypro's gave and the smoothness of there operation outweighed the top end, so that is where i stayed.

aren't you really comparing a 4-blade (baypro) to a 3-blade (stiletto) prop? I would think that's what is affecting a calculated slip (4% vs 9%) the most.

for the original comparision- 3x14.25x21 aluminum at 54mph ? rpm versus 4x14x19 aluminum at 50mph at 5000 rpm,

stainless props have less drag, less blade flex, and are more efficient than aluminum props. I would first go with stainless prop at 3x14x21.

A 4-blade prop, because of the extra blade hopefully obvious, will have more bite (less slippage) but at the result of drag so you'll need more horsepower to turn it at high rpm's, or your top end will be slightly slower (less mph less rpm) because of the drag of the extra prop.
4-blades are more for heavier boats, in my opinion 24' and larger. For your regular 20' boat, I think you'd be better off with a 3 blade. If you're hole shot sucks because the motor holds steady around 3000 rpm as the boat is planing, then your prop is biting and it's a horsepower not a prop issue- either get more power out of the motor or lower the prop pitch but then it's at the expense of top end speed. What you can do in this case is find a prop with exhaust ventilation holes, they will help the prop slip when the boat planes by routing exhaust over the blades, it'll let the motor rev more into it's power band which might help. Or you can find a 3-blade prop with slightly less diameter, 14" or 13.75" is very common. On the other hand, if you can go full throttle and the rpm's shoot to 3500-4000 but the boat don't get on plane fast then it is a prop issue and you're not getting good bite- a 4-blade will definitely help here but so might a better 3-blade prop. In your case, you got great holeshot out of a 4x14x19 because you dropped 2" in pitch and added an extra blade!
Try any name brand stainless prop, they are all pretty good,
tiletto or turbo (both by precisionpropeller),
or solas,
or any of the stainless' by michigan.


I would bet your were turning 4800 rpm with your original 3x14x21 aluminum prop at 54mph given ~10% slip.

Ratio	1.6				
Efficiency = 0.91  (9% slip)					
rpm/pitch	18	19	20	21	22
1000		9.7	10.2	10.8	11.3	11.8
1500		14.5	15.3	16.2	17.0	17.8
2000		19.4	20.5	21.5	22.6	23.7
2500		24.2	25.6	26.9	28.3	29.6
3000		29.1	30.7	32.3	33.9	35.5
3500		33.9	35.8	37.7	39.6	41.5
4000		38.8	40.9	43.1	45.2	47.4
4200		40.7	43.0	45.2	47.5	49.8
4400		42.7	45.0	47.4	49.8	52.1
4600		44.6	47.1	49.6	52.0	54.5
4800		46.5	49.1	51.7	54.3	56.9
5000		48.5	51.2	53.9	56.6	59.2
5200		50.4	53.2	56.0	58.8	61.6
5400		52.4	55.3	58.2	61.1	64.0


Ratio	1.6				
Efficiency = 0.96 (4% slip)					
rpm/pitch	18	19	20	21	22
1000		10.2	10.8	11.4	11.9	12.5
1500		15.3	16.2	17.0	17.9	18.8
2000		20.5	21.6	22.7	23.9	25.0
2500		25.6	27.0	28.4	29.8	31.3
3000		30.7	32.4	34.1	35.8	37.5
3500		35.8	37.8	39.8	41.8	43.8
4000		40.9	43.2	45.5	47.7	50.0
4200		43.0	45.3	47.7	50.1	52.5
4400		45.0	47.5	50.0	52.5	55.0
4600		47.0	49.7	52.3	54.9	57.5
4800		49.1	51.8	54.5	57.3	60.0
5000		51.1	54.0	56.8	59.7	62.5
5200		53.2	56.1	59.1	62.0	65.0
5400		55.2	58.3	61.4	64.4	67.5

 

[Tail_Gunner]

Re: Prop options

Take it for what is worth, going to a SS will cost you 200 rpm, as to the cupping your just adding bite or effective pitch. Yep the 3 blade was a stilletto and as was the 4 blade.....same cupping......just one more blade...effectively more bite.....Umm alum deform's ron, and when it does it also deform's the pitch effectivley Umm and it is also thinner which allow's the higher rpm,........Umm that's why the Merc's x7 alloy is supposed to be such a big to do... that is it turn's as fast a a alum it's just as thin with no deformation....allowing higher rpm and higher speed..


"aren't you really comparing a 4-blade (baypro) to a 3-blade (stiletto) prop? I would think that's what is affecting a calculated slip (4% vs 9%) the most."

Think of it like this.....Prop mfg claim's if you use my 4 blade SS it will reduce your slip by 50%......Not gonna happen the prop in this instance just had more grip called cupping.


Just a thought your milage may vary.......... alot in this case...

 

[silverbullet]

Re: Prop options

On the other hand, if you can go full throttle and the rpm's shoot to 3500-4000 but the boat don't get on plane fast then it is a prop issue and you're not getting good bite- a 4-blade will definitely help here but so might a better 3-blade prop.


Ron- it looks like this should be the next peice of performance data I need to aquire, along with WOT RPM of the 3x14x21. Let's just say that I first check the 4x14x19 holeshot rpms and they're 3500-4000, would that mean I might should try a 4x14x20?

Does this pic if it works shed any light? New 4x14x19 after 15 hrs.

 

[silverbullet]

Re: Prop options

Well if you squint your eyes just right you'll see that two of the blades tips have lost their paint on the backside, one tip on the front side also. It wasn't worn off- more like flaked off with jagged edges..... cavitation damage?? or just lame paint?

 

[mrclean]

Re: Prop options

I put a 4 blade stilleto on it and gained 5 mph and a lot of other good thing's

Gunner
So you have a 18p 4 blade on your boat now? I ask because I have an 17p
Enertia on my 18'6 bowrider with 4.3 Gxi (225hp) with a 1.60 sx drive. I'm
not that happy with it for the price. It does jump out of the hole with good
mid-range but it will only go 50mph at 4700rpms. I'm looking for a little more
topend. What is your WOT mphs and rpms?
Thanks,

 

[Tail_Gunner]

Re: Prop options

Gunner
So you have a 18p 4 blade on your boat now? I ask because I have an 17p
Enertia on my 18'6 bowrider with 4.3 Gxi (225hp) with a 1.60 sx drive. I'm
not that happy with it for the price. It does jump out of the hole with good
mid-range but it will only go 50mph at 4700rpms. I'm looking for a little more
topend. What is your WOT mphs and rpms?
Thanks,

You should start a new thread, something is wrong........Your number's show 0% slip....... and that motor should be banging the rev limiter with a 17

 

[silverbullet]

Re: Prop options

Tail Gunner-
I'm starting to think that efficiency is a big part of my problem, like you mentioned. With the 4x19 VP from a idle speed start I have plenty of power as I only need a very brief shot of WOT to plane and quickly throttle back, yet last few mph at top end are slow to come around and doesn't overrev, yet with the VP 3x21 I'd floor it, make alot of noise and bow rise but not get out of the water. Obviously, I'd like to just buy only one more prop, not 2-3-4-5.

So out of the 7 props mentioned here would I have I correct in ranking them for best holeshot:

1)Stilletto BP II 4x18
2) Volvo penta 4x19
3)MW Apollo 4x20
4)Stilletto Advantage 3x19
5) Stilletto BP II** 4x20
6)Stilletto Adv 3x21
7) VP 3x21


-and best top end:
1)Stilletto 3x21
2) Stilletto 3x19
3)MW Apollo 4x20
4) VP 3x21
5)Still BPII 4x18
6)VP 4x19
7) Still BP II** 4x20

** probably unpullable

 

[Tail_Gunner]

Re: Prop options

Tail Gunner-
I'm starting to think that efficiency is a big part of my problem, like you mentioned. With the 4x19 VP from a idle speed start I have plenty of power as I only need a very brief shot of WOT to plane and quickly throttle back, yet last few mph at top end are slow to come around and doesn't overrev, yet with the VP 3x21 I'd floor it, make alot of noise and bow rise but not get out of the water. Obviously, I'd like to just buy only one more prop, not 2-3-4-5.

So out of the 7 props mentioned here would I have I correct in ranking them for best holeshot:

1)Stilletto BP II 4x18
2) Volvo penta 4x19
3)MW Apollo 4x20
4)Stilletto Advantage 3x19
5) Stilletto BP II** 4x20
6)Stilletto Adv 3x21
7) VP 3x21


-and best top end:
1)Stilletto 3x21
2) Stilletto 3x19
3)MW Apollo 4x20
4) VP 3x21
5)Still BPII 4x18
6)VP 4x19
7) Still BP II** 4x20

** probably unpullable

1 Stilletto 3 blade 19 best speed
2. Appollo 4 blade best overall performance and maybe speed
3. Enertia 20 but expensive
4. 18 pitch Baypro

5.Make sure your tach is accurate with in 100 rpm prior to buying if you can.

 

[silverbullet]

Re: Prop options

THANK YOU Tail-gunner!