Prop recommendations for Yamaha F115

[Hacker]

I have a 2001 F115 on 19' 2002 G3 mod-V hull aluminum bass boat. I currently have the original 21P Yamaha stainless prop and my performance is not as I expected. With only myself on the boat with fishing gear, the gross weight is ~2250lbs and I am only topping out at 42.6 mph on the GPS at 5800-6000 RPM. Looking at one of the prop calculators, I would expect to get between 46 and 49 mph with ~10-14% slip (2.15 gear ratio). I feel I can get a little more RPM trimming up, but did not test there. The speed did not increase above the 6000 mark. Also for reference, my stabilization plate is ~ 2" above bottom of boat (just eyeballing it).
I'm looking to get a new SS prop and would like to get my speed up so I am cruising with 2 guys in low 40mphs. My guess is that I could go up to a 22P prop, but I do not want to slow my holeshot any more than I get with the 21P... So was thinking of a 21P 4-blade... But which one would be recommended to try and get me there? Or is there a recommended 3-blade that could benefit my mid and top end with still solid

Thanks for the help.

 

[steelespike]

Re: Prop recommendations for Yamaha F115

Seat of my pants;
Compared to similar smaller lighter boats I think your speed is excellent as well as your rpm. In my mind speeds above 43 would be the exception.Especially in a 19.
Cruising at above 40 doesn't seem likely to me. Its very likely a 4 blade will lower your top end.Prop calculators in my experience are overly optimistic. And slip calculators are only as accurate as their input.Someone with more prop smarts than me may be able to tweak your setup but don't hold your breath for a lot of increase.

 

[Hacker]

Re: Prop recommendations for Yamaha F115

Thanks. I agree that calculations are only theoretical as a water test is the only real way to know. My question is also more about some of the higher performance props with progressive pitch and cupping compared with stock props. I have looked at the Rubex HR4 Titan, the Michigan Apollo and the Stilletto Advantagein the 21P and the Quicksilver Lightspeed in the 22P... but these are just names to me. I don't feel good going and testing these at >$300 each. that gets expensive quick!

 

[Hacker]

Re: Prop recommendations for Yamaha F115

Does anyone have experience with the Yamaha performance SS props (Pro series or Performance series) compared with other brands like Solas or Michigan?
I talked to the local Yamaha dealer and he recommended a 13x23 Yamaha Performance series prop for my boat due to me hitting the 6000 RPM rev limiter before WOT (didn't know I had a rev limiter). I'm thinking this may be too much prop? And also have a problem with the >$600 sticker price. I've searched online and found the prop for $500, but that's still well about the ~$350 range of the other brands.

Thanks.

 

[mommicked]

Re: Prop recommendations for Yamaha F115

Yamahas outboard website has performance reports w info on speed and props used.I saw one for a 19 G3 jonboat says 48mph at 6000 w a 19 pitch w the 115. I think G3 bass boat hulls are different than the jons.and the new motors are fuel injected, my 03 F90 is carbed.chek the website

 

[walleyehed]

Re: Prop recommendations for Yamaha F115

Don't overlook your gear ratio....2.15:1 as opposed to 2:1 or 1.86:1.
You're going to use slightly more pitch to get the same results.
Do you have a jackplate? how high is the engine mounted?
There ARE 4blds out that you can keep or even gain speed with, but a jackplate is a must....if you can't get the engine up where it needs to be, you won't be able to use the technology of a good 4bld.
Oh, forget the apollo....look at the top of the prop forum and read my test results with the apollo-good prop, but not the fastest especially on the rig you have.
This may be a good application for a Turbo.....depends what year your yammy prop is...

 

[Fisher3491]

Re: Prop recommendations for Yamaha F115

I don't think a 13 x 23 is too much prop, if like walleyehed says, your engine is mounted high enough. Too low in the water and it will drag. I have a 13 x 21 on my F115 and its hits 6000 before WOT. 42mph with three people. It came mounted in the second hole from the top with the cavitation plate level with the keel. We moved it up to the bottom hole and still find its too low. Will have to get a jackplate. Get the motor as high as you can without it ventilating in the turns and you'll need a 23!

 

[Hacker]

Re: Prop recommendations for Yamaha F115

Thanks for the info. I checked out the mounting brackets and the motor is as low as it will go and the plate is 1 1/2 to 2 inches above the keel. With the current 13x21 prop, I will cavitate on a buttonhook turn even with it trimmed all the way down. With a more normal turn, I trim down just a bit off speed point and it won't cavitate. Due to these two characteristics, I'm afraid to raise the motor any... At least not yet.

Also, comparing my boat to the Jon boat will be quite a bit off just due to weigh alone. I'm quite a bit heavier than a basic Jon boat.

As for the 13x23, I think I will get one (or maybe a merc 13x22) and then play with all the variables to see how it does. Do to this, I will tune to performance and then get a family prop for tooling around (which I did Saturday and it ran great except for the buttonhook cavitation and lack of holeshot while pulling... Can't have it all with one prop).

Now about the jack plate... Does this help with cavitation? I was told to go no more than a 6" offset. I found a manual Jack plate for $250 that has a 5 1/2" offset and was thinking about getting it, but just didn't know enough about them.

Thanks.

 

[Hacker]

Re: Prop recommendations for Yamaha F115

Thanks for the info. I checked out the mounting brackets and the motor is as low as it will go and the plate is 1 1/2 to 2 inches above the keel. With the current 13x21 prop, I will cavitate on a buttonhook turn even with it trimmed all the way down. With a more normal turn, I trim down just a bit off speed point and it won't cavitate. Due to these two characteristics, I'm afraid to raise the motor any... At least not yet.

Also, comparing my boat to the Jon boat will be quite a bit off just due to weigh alone. I'm quite a bit heavier than a basic Jon boat.

As for the 13x23, I think I will get one (or maybe a merc 13x22) and then play with all the variables to see how it does. Do to this, I will tune to performance and then get a family prop for tooling around (which I did Saturday and it ran great except for the buttonhook cavitation and lack of holeshot while pulling... Can't have it all with one prop).

Now about the jack plate... Does this help with cavitation? I was told to go no more than a 6" offset. I found a manual Jack plate for $250 that has a 5 1/2" offset and was thinking about getting it, but just didn't know enough about them.

Thanks.

 

[walleyehed]

Re: Prop recommendations for Yamaha F115

Yes...it will help with Ventilation. Is your hull the semi-V bass-style hull??

 

[Hacker]

Re: Prop recommendations for Yamaha F115

So an update on my situation. I was looking for a top speed prop, but also needed a torqy prop. I came across a great deal on a 4 blade Turbo flats stainless prop in a 13 1/4x18. I wanted to use this for taking the family out and pulling the occasional tuber...

Well to my surprise, the Turbo prop... with a 3 degree pitch drop... gave me a better top speed than the Yamaha Stainless 13x21. I ran it this weekend just to test and got a top speed of 44 MPH! If I use a prop calculator, that puts me at ~6% slip compared with ~21% for the yamaha prop. I also hold better turns, have a superb holeshot and trim the motor much farther out riding the top of the water. The other amazing part is that I can still hold 43.2 MPH with a second passenger.

Of course me being me, I instantly start thinking of the next best thing and now "what do I need for top speed". I am on the CA Delta and ran 3/4 throttle with the tide for this speed and WOT running against the tide. So I may just test out the 13 1/4x20 Turbo 4 blade and see if that becomes my speed prop. Even if a get a tad more slip, this could put me up closer to 48MPH! If I could hold ~40-42MPH at 3/4 throttle, I could go forever on a tank of gas.

Thanks.