Looking at perhaps going from a 17P three blade to maybe a four blade (not sure on pitch) on a Yamaha VF115 SHO. I think I'm under-pitched a little with my current prop (WOT is a tick over 6400 RPM read off NMEA, around 42-43 MPH on GPS). I get cavitation pretty easily in turns and on the hole shot if I don't trim down quite a bit. I figure a 4 blade will have better grip and less cavitation, but I wanted to see what other folks' experiences have been.
JW sounds like you have a couple things going on with your set up. Can you give us some detail about what boat you have and what your prop to pad measurement is. It also sounds like you are also over revving so it is likely that a higher pitch prop may be required. I would not consider a 4 blade until we know what your other numbers might be.
Quote from: J.W. on April 29, 2022, 08:46:03 AM
Looking at perhaps going from a 17P three blade to maybe a four blade (not sure on pitch) on a Yamaha VF115 SHO. I think I'm under-pitched a little with my current prop (WOT is a tick over 6400 RPM read off NMEA, around 42-43 MPH on GPS). I get cavitation pretty easily in turns and on the hole shot if I don't trim down quite a bit. I figure a 4 blade will have better grip and less cavitation, but I wanted to see what other folks' experiences have been.
Four blade will definitely give you more grip and generally you drop 1" in pitch in pitch when moving to a 4 blade, but the big question is weather a 17 pitch is the best three blade. If you're running too small of pitch to begin with you'll get cavitation under almost all conditions. 17 sounds about right but, I agree with bud, prop to pad distance would be a good information to have before making any recommendations or suggestions.
Quote from: Princeton_Man on April 29, 2022, 09:35:54 AM
Four blade will definitely give you more grip and generally you drop 1" in pitch in pitch when moving to a 4 blade, but the big question is weather a 17 pitch is the best three blade. If you're running too small of pitch to begin with you'll get cavitation under almost all conditions. 17 sounds about right but, I agree with bud, prop to pad distance would be a good information to have before making any recommendations or suggestions.
Right. I'm thinking I should be on at least a 19P for 3-blade. If the motor is mounted too high, then I'm going to trim down and just live with it until I can bite the bullet on a TH Marine Micro Jacker and a water pressure sending unit.
On measuring pad to prop, you guys might have to educate me. I don't really have that flat pad area like on a bass boat. It's a War Eagle Blackhawk. Kind of a shallow V all the way back.
I sold and rigged a lot of boats over twenty years. It would be a rare deal indeed for a four-blade not to be an overall improvement in almost any fishing/bass boat. A SLIGHT loss in speed is the only real issue and that is more than offset with the benefits gained.
Still, your base set up needs to be close. A four-blade should not be a BANDaid.
You still measure flat off the bottom to get your height. War Eagles are tremendous boats- I'm sure that they can be of help to you to get a base line, and I'd for sure start with them. The Ward family (do they still own War Eagle?) were/are GREAT folks.
Dale
Quote from: D.W. Verts on April 29, 2022, 02:57:38 PM
I sold and rigged a lot of boats over twenty years. It would be a rare deal indeed for a four-blade not to be an overall improvement in almost any fishing/bass boat. A SLIGHT loss in speed is the only real issue and that is more than offset with the benefits gained.
Still, your base set up needs to be close. A four-blade should not be a BANDaid.
You still measure flat off the bottom to get your height. War Eagles are tremendous boats- I'm sure that they can be of help to you to get a base line, and I'd for sure start with them. The Ward family (do they still own War Eagle?) were/are GREAT folks.
Dale
I'll measure it when I get home.
Yessir, the Ward family still owns War Eagle. Still built in Monticello.
Alright just measured the gap and it's 4" with the engine mounted on the second hole. Got busy building recirculators for the livewells, and just got around to measuring.
J.W. just to confirm your measurements, here is a drawing showing the correct way to measure.
(https://imagizer.imageshack.com/v2/xq90/924/iUz1m7.jpg) (https://imageshack.com/i/poiUz1m7j)
Quote from: J.W. on May 01, 2022, 11:22:59 AM
Alright just measured the gap and it's 4" with the engine mounted on the second hole. Got busy building recirculators for the livewells, and just got around to measuring.
If you measured properly, your prop shaft is 4" below the pad, and you have as much trouble with cavitation as you say, then I would suggest your prop is too small of pitch.
This does not seem to add up for me. Please re check your prop to pad measurement using the sample drawing I provided earlier. My sense is that your prop is actually too shallow. This however can be verified by re doing the measurement. The conditions you describe sure do indicate a too shallow condition in my book.
It looks as if the 19P prop should be good for this unit although it seems a bit light when comparing to a traditional bass boat set up. I understand this is not a bass boat and I see that a 19P is fairly common on this make of boat. I'll just bet if you move the motor to the top hole it may help your problem but let the measurement numbers confirm all of that.
The blow out condition you describe should not happen with a proper set up. My strong opinion is set up first then prop consideration second.
Brother, do you have a blade out of whack? Asking for a friend...
Dale
I'll see if I can take some pictures tomorrow.
Ok, trying to post pics for the first time here.
Hopefully they aren't huge.
So because I don't have a pad, that keel ridge runs all the way to the stern. Do I include that in the measurement? If so, it's around 15" from the ground. If I ignore that ridge, it's around 16" to the ground. The centerline of the prop nacelle is about 11 from the ground. Reason I say "about" is I don't have pavement at my house to check it on. Hopefully those pics do a better job than I could at explaining it.
Sorry, I don't know why the pictures came out sideways.
JW, please use the picture drawing I posted a couple days ago in this thread. This has nothing to do with the ground. It is a measurements from (in your case) the bottom of the boat to the center line of the prop. It is important to have the boat level and the motor trimmed down perpendicular to the boat. So in fact the motor is straight up and down and the boat is level front to back. We are looking to establish a measurement to determine how far below the bottom of the boat your prop center line is. Most likely this baseline number is around 3 to 4" If you read the text around the drawing I provided it will also give you the correct way to set up the boat and motor for measurement. The pictures you provided do not indicate you are making the correct measurement. You might want to go someplace where you can take this measurement on a hard surface just to be accurate. In this kind of set up a 1/4" or 1/2" can make a big difference.
I'm not much good at determining optimal setups but I have a few ideas.
I have a VF115 sho on my stratos. The setup is a 13.125" 19p. It's a good all around performer. I don't run it at max throttle very often and still pull 48mph on the gps.
I think your 17 is too small of a pitch and it shows with your blowing out and super high rpms. You're almost maxed out at 6400 and I think most people are trying to stay under 6k.
The Yamaha prop selector shows even stepping up to a 20 or 21p to get those rpms down some.
Try and level your boat up best you can and check those setup measurements. If those are in the ballpark id start looking for a bit more pitch. Good luck!
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Quote from: Bud Kennedy on May 02, 2022, 09:04:12 PM
JW, please use the picture drawing I posted a couple days ago in this thread. This has nothing to do with the ground. It is a measurements from (in your case) the bottom of the boat to the center line of the prop. It is important to have the boat level and the motor trimmed down perpendicular to the boat. So in fact the motor is straight up and down and the boat is level front to back. We are looking to establish a measurement to determine how far below the bottom of the boat your prop center line is. Most likely this baseline number is around 3 to 4" If you read the text around the drawing I provided it will also give you the correct way to set up the boat and motor for measurement. The pictures you provided do not indicate you are making the correct measurement. You might want to go someplace where you can take this measurement on a hard surface just to be accurate. In this kind of set up a 1/4" or 1/2" can make a big difference.
Thanks Bud. I looked at it, but I mentioned measuring from the ground because I thought you were supposed to get pad-to-ground measurement ("A" in that diagram) then prop shaft-to-ground measurement ("B") and then finally take the difference to get the gap. Sounds like maybe I'm misunderstanding it? I got 15"-11"= 4" if I'm going about it the right way, but like you said, it's definitely not on pavement. If I need 1/4" accuracy I'll have to do it somewhere else. The only level concrete I have is in my shop, and the trailer won't fit in there. I can take it to some level pavement and get some more certain numbers later this week if it'll help.
Based on what I see in the pictures, you should be measuring from the weld, not the triangle point. Your boat isn't running on the triangle point, but rather the rest of the pad. If I was in your shoes without any concrete or asphalt, I would get a rigid yard stick or 1x2 that is straight and flat and hold it along the pad and have someone measure the gap between prop shaft and yard stick.
A rigid yardstick that is flat and straight can held against the pad of the boat and the boat doesn't have to be level. You can then match the level of the yardstick by trimming your motor until it is exactly parallel to the yardstick. Then measure the gap to the nearest 1/4".
Quote from: apenland01 on May 03, 2022, 09:22:58 AM
Based on what I see in the pictures, you should be measuring from the weld, not the triangle point. Your boat isn't running on the triangle point, but rather the rest of the pad. If I was in your shoes without any concrete or asphalt, I would get a rigid yard stick or 1x2 that is straight and flat and hold it along the pad and have someone measure the gap between prop shaft and yard stick.
A rigid yardstick that is flat and straight can held against the pad of the boat and the boat doesn't have to be level. You can then match the level of the yardstick by trimming your motor until it is exactly parallel to the yardstick. Then measure the gap to the nearest 1/4".
Thanks! I will try that.
From everything I've seen so far, I'd certainly be looking at trying a 19P. You're not that high. If you have a marine dealer on the water or a dealer who does some kind of trial, I'd be talking to them. Some shops have demo props for the sole purpose of helping you find the right prop. You currently have far too much much slip with that 17P, more than you have adjustment for.
Using Yamaha's Prop selector, inputting your data and boat type, Yamaha is recommending a 20P or 21P. I'd say they're right. Maybe a 20P FX4 four blade.
https://www.yamahapropselector.com/propSelector/web/inner.html (https://www.yamahapropselector.com/propSelector/web/inner.html)
Tried to measure it again using the straight edge technique instead of measuring from the ground, and got similar numbers. The gap is around 4" if I include the triangular cross-section of the keel rib. If I exclude that triangle, I get a gap that is between 5" and 6." Hard to measure that way because the tape is "floating" out next to the prop shaft if I keep everything square and level. I think it's good enough to say that the prop is not too shallow, though.
I guess I need to try some props in the 19"-21" pitch range maybe.
Sure sounds like it. I would have bet you were too shallow but you measurements indicate that is not the problem. Happy prop hunting.
Quote from: Bud Kennedy on May 05, 2022, 01:35:36 PM
Sure sounds like it. I would have bet you were too shallow but you measurements indicate that is not the problem. Happy prop hunting.
Thanks, Bud. PowerTech is local to me, I might see if they do to "try before you buy" thing.
JW, where are you in NW La? I live in N. Bossier and can try and stop by or meet up with you at a ramp or something and see if I can help out. Ive never owned a War Eagle, but I did have a Yamaha 115, and it had a 19 on it and it worked great. According to your RPM's, I think part of the issue is the pitch.
You're not far. I'm just north of Bossier.
Alright, made a few phone calls yesterday. Here's what I learned.
PowerTech in Shreveport does not do the "try before you buy" thing anymore. Crap.
Called Team Ward, the company that makes War Eagle boats. The fella I talked to was super helpful and confirmed that the dealer mounted the engine in the recommended holes, but was pretty shocked that it was propped with a 17P. He said he ran the exact same boat as me once with a 19P PowerTech PTR3, which is slightly bigger in diameter and cupped quite a bit more. He said it ran great, so I should probably be running a 19P at minimum.
I think I'm just gonna trim down some, lay off the throttle a little, and live with this prop for a little while until I finish getting these lithium batteries paid off, then I'm going to get a different wheel.
That Yamaha prop selector keeps hinting at props in the 20-21 pitch range, which sounds about right to me.
Quote from: J.W. on May 11, 2022, 10:00:17 AM
Alright, made a few phone calls yesterday. Here's what I learned.
PowerTech in Shreveport does not do the "try before you buy" thing anymore. Crap.
Called Team Ward, the company that makes War Eagle boats. The fella I talked to was super helpful and confirmed that the dealer mounted the engine in the recommended holes, but was pretty shocked that it was propped with a 17P. He said he ran the exact same boat as me once with a 19P PowerTech PTR3, which is slightly bigger in diameter and cupped quite a bit more. He said it ran great, so I should probably be running a 19P at minimum.
I think I'm just gonna trim down some, lay off the throttle a little, and live with this prop for a little while until I finish getting these lithium batteries paid off, then I'm going to get a different wheel.
That Yamaha prop selector keeps hinting at props in the 20-21 pitch range, which sounds about right to me.
Yup, that''s pretty much what I suspected. Dealers are notorious for not getting the setup right. At least they got the motor mounted at the recommended height.
When you are ready, BB Blades is an online company and has a try before you buy type deal. You pay a small fee to try out different props based on their availability and send them back within the time frame. I was going to use them but they were out of stock on the prop that I wanted to try and I got tired of waiting. They might work out for you. Check them out online.
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Quote from: FlatsNBay on May 14, 2022, 06:36:03 AM
When you are ready, BB Blades is an online company and has a try before you buy type deal. You pay a small fee to try out different props based on their availability and send them back within the time frame. I was going to use them but they were out of stock on the prop that I wanted to try and I got tired of waiting. They might work out for you. Check them out online.
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Hey, thanks! I'll bookmark it.
So I finally got around to re-propping this thing.
Ended up with a PowerTech PTR3 three-blade in 19 pitch. That's what PowerTech and Team Ward (boat manufacturer) both recommended, so I ordered one. It has way more rake and cup than the original prop, a bigger diameter, and two more inches of pitch. I put it on yesterday and ran it some with a full fishing load and three people in the boat.
Big difference. It dropped my rpms back into the recommended range, I can turn without blowing out, and my boat doesn't wander all over the place at low speed. The hole-shot is slightly slower now, but still excellent. It used to be pretty much instant with the 17P I had, but now it takes about 1-2 seconds. It also reverses much better now than it did before. Also increased my top speed from 43 mph to 46. There was a lot of chop when I ran it, so with less wind I might can squeeze one or two more mph out of it, but with this type of boat, speed was never really my concern to begin with. I'm pretty pleased with it so far.
i actually cant believe i missed this thread
way back in 2018 when i got the PHX, it was a 24 fury 3 blade and i did not like it at all. Switched first to a bravo 26 but dinged it up pretty good and then went to the 24 bravo.
the holeshot, and ride are just great and i can still touch 70 or get real close. normal speeds are about 50 - 55 -- the ride is just incredible at that speed. its like you are on a waterbed.