Prop for 115 Yamaha on guide boat

[Random guy]

I have grond up another prop and I need to replace it today or tommorow. Before I run off and buy another 13x19-K alum yammi prop I thought I would look at other options, such as a comprop, ventilated etc etc.

Trouble I have is I'm running full RPM (6000)loaded with five guys or by myself. By myslef the boat is up on plane in sconds but four guys in the boat it barely gets out of the water. So less pitch would help that but I will lose huge top end and start bumping the rev limiters and on Red I can't afford to lose top end speed since I travel seven eight or ten meiles every time I move. Stainless would be best for performance but I refuse to run stainless on Upper Red, I bang the bottom to much for stainless even though a four blade stainless would help greatly.

Ideas you boat wizards, maybe go buy my Stratos back?

[Valv]

Jon,

I think your only option is aluminum, and get a spare just in case. I don't like Comprops, they are plastic, when you hit a log or obstacle the blades break off completely leaving you with no propulsion. Motor and prop spin but there's nothing to push the boat, you are at the mercy of kicker or trolling motor. I've also seen some that did loose 1 or 2 blades making it so unbalanced you can barely stand it at idle.

[Surface Tension]

I'm surprised that your getting the same 6000 RPMs with a full load and empty. Sounds like you need two props anyway.

Might want to go up in pitch on the spare.

[Hula_Grub]

I got a comp prop last year after I bent my prop shaft. The blades are available individually for around $15, and you can experiment with what ever pitch you want for around $45 to $60 a propeller. Upfront costs for the hub, etc. are a little higher. The "shearing" of the blades is meant to protect you from bending your shaft.

I spent the last 5 years flying a composite-propeller airplane for a living. When I saw the piranha site, I was sold.

[Random guy]

I'm surprised that your getting the same 6000 RPMs with a full load and empty.

Thats what gets me. Yesterday I had three good sized dudes and me in the boat, thats works out to roughly 900-1,000 pound of flesh, a full livewell or 200lbs of water and all sorts of gear not to mention a cooler with 20lbs of ice in it and I could rev it right up to 6100 rpms once I got out of the water. A couple of times I was wondering if the boat was ever going plane out. Now once I dropped off 1,300lbs of poeple, water and the cooler my hole shot was incredible but I maintained the same top end speed as if I was loaded full.

My current three blade is worn no doubt about it, could I get that much flex with a thin worn out prop?

I am looking at the alm. four blade props made by a few prop companies, maybe the best of both worlds?

I do know the best thing I ever did to my Stratos was run a four blade Rampage prop, that thing would jump out of the hole no matter how many clients I had and I would swear that thing was grabbing gears as I climbed into the 60mph range. Only thing I wonder is if the four blade on a smaller four stroker will have the same effect and that was a stainless prop and I put on four lower units running it. The mechanics told me every time I had to lose the stainless/stay out of the sand or keep buying lower units. Another reason for alm verses stainless is trying to position the boat in heavy winds, lots of foward reverse going on that the lower unit can't handle with a heavy stainless hanging on it.

[Random guy]

you are at the mercy of kicker or trolling motor.

I used to own a FICHT,I'm used to that.

[cjac]

I have the same motor, and still can't do any better than the 13x19 alum. With the planing issues and the high RPMs, I do wonder if it's cavitating or possibly the prop hub is slipping just a bit?

[PerchJerker]

I think you get more slip with aluminum than with stainless. I also think 115 hp is right where to start to see some benefits from stainless, more as you go up in horsepower.

I've never run a composite prop but have not heard good things about them. I wonder how much performance you might lose with a comp prop and a load???

I think staying the same or trying a 4 blade aluminum are your best options.

[Random guy]

I think four blade aluminum and send the three blade off to get re-built and maybe a hub popped in it.

[Northlander]

Sounds like slip to me but if your getting out of the hole ok with a load I dont think its a hub. With that 115 yammy 4 stroke you want to be running about 5800 or a tad higher at WOT. If your in the 6000 range at WOT your high. You can do it but in the long run I think its hard on the motor. I think I remember reading that at 5800 rpm that motor is actually getting 115 out of it.

What boat are ya running it on?

Call or e-mail Jay Soderbloom (www.soderbloom.com) and bounce it off him. He knows his props. A local FMer here just put a 17 stainless on his 115 yammy 4 stroke and seems to like it.

Also check your tach. I have a hard time believing your at 6000 with that many guys and that big a prop. Especially if your not blowing out in the process.

I would go stainless and just stay out of the sand/gravel/rocks. You will notice a big increase in performance.

I havent found a alum prop that can give me good holeshot, top end, cornering without having too many rpm's.

[Random guy]

Well I already talked to Jay Solderblooms and he agreed with the marine techs and performance guys I spoke with most of the morning. All but one agreed that a four blade is the way to go. He had one in stock and it is on the way. Great guy to deal with and really knows his stuff.

Reason for it is I carry massive loads for that size of boat/motor. A four blade will give me a much better hole shot with such load on along with better rough water/corning compaired to three blade. The high RPMs are coming from the way I have my boat balanced and motor set. Basicaly the hull design in the chop/low waves is blowing out the prop along with a worn prop adding up for huge amounts of slip.

Now a stainless four blade would be best but their is no way I will stay out of the sand on Upper Red, I think I hit sand four times yesterday running for pike. Remember we are targeting fish in 2.5-4.5 feet of water right now. Another con to the stainless and me is the constant forward/reverse action of moving around a marina, positioning of the boat over structure for anchor up and the fact I have to dock my boat at least four times every day at the very least. The heavy stainles will tear up the lower unit from all the direction changes.

Another thing I learned is a four blade will out produce in holding a boat in the wind simply because the way it "cuts" or moves the water.

[marine_man]

With that 115 yammy 4 stroke you want to be running about 5800 or a tad higher at WOT. If your in the 6000 range at WOT your high... I think I remember reading that at 5800 rpm that motor is actually getting 115 out of it.

If it's a 4 Stroke (and I think it is) yamaha's top end on the rpm spec is 6000 - no reason not to run right at that in my opinion.

Good luck with your new prop Jon! Sounds like you made the right choice...

marine_man

[Northlander]

Ya you can run at 6000 if you want but from what I have read and heard is that that motor, same as mine, runs at peak performance when in the 5800 range. Im no expert but I have found on my rig that this seeems true. At WOT and trimmed up to best level I run right around 5800 and get peak speed out of my motor. Alone and average load I get about 43 mph, light I can hit 45mph and with a big load and another guy I am in the 40 mph range. Good hole shot and I can corner without any problems or having to mess with trimming down.

Ya I can make it run at 6000 but I lose performance and I think its easier on a motor when your not always at max rpms.

Marine Man correct me if Im wrong but Im going by what yamaha writes, techs and other 115 yammy 4 stroke owners ahve told me.

[marine_man]

I can make it run at 6000 but I lose performance and I think its easier on a motor when your not always at max rpms

[Northlander]

In order to get 6000 I have to trim up too far and of course then lose speed and steering etc.

Have you heard that at 5800 rpm is where you actually get the full 115's power?

So would you try to get up to 6000 consistantly when at WOT without blowing out and losing speed and control?

With my 2 alum props I have no problem running 6000 and more at WOT. I havent found a alum prop that Im happy with. Ill see how Johny makes out and maybe Ill go a 4 blade alum for a spare or river prop.

Right now with the stainless prop I run I dont have much boat in the water at all when at WOT and the "Sweet spot" is at about 5800 rpm. I know several guys with the same boat and motor and the most anyone is getting is 43-45 mph. 45 is my max so I think Im ok.

Of course if I could get a prop that would let me run at 5950 or so and keep my hole shot and be faster that would be cool as well.

Prop games get expensive though.

[BoxMN]

Just my two cents... but if you are only hitting sand and not rock, then a SS would be ideal. It won't get ground down like alum, thus lasting much longer. I also don't think that SS is going to have the effect of wearing out gears from shifting in and out, but I am not sure about that. SS props are made for those motors, and vice versa.

But if you do hit rocks then yes, I would not get SS. I don't know Red, so forgive me if I am totally off base. Good luck with whatever you get!

[marine_man]

In order to get 6000 I have to trim up too far and of course then lose speed and steering etc.

What's your definition of "too far"? Is the boat porposing? The ideal running location is at 6k, motor trimmed up until the boat starts to porpise, then back down just until the boat stops porposing. You will in all likelyhood have to trim back down to corner, but that's the max speed running position. No, I haven't heard explicity that 5800 is where you get the most power, but from a speed standpoint rpm's = propeller rotation = speed.

I'd have to see the hp vs torque curve to tell for find where you're getting your max power, but I would say that max torque is a bigger deal when you're trying to get the boat out of the water at holeshot.

I would try and find a combination that lets you run at 6k with you and a medium to light load of gear / livewell water, etc without blowing out or forsing you to porpise to get there.

marine_man

[Northlander]

No porposing just loose speed and steering ability because there isnt enough boat, ;)prop/lower end in the water. Like I said this prop at 4800 rpm gives me max speed, good steering and cornering and throws a nice rooster. They call it "Ranger Envy" I guess.

I will see if I can try a couple other stainless props and see what I find out on the RPM range.

I have a specially done prop from Jay Soderbloom now. It has exhaust holes, cupping, thinned blades and some more agressive top edges. I really like the way it holds the water in corners, I never have to trim back down like I had to with other props.

[marine_man]

Sounds like you're running pretty close to optimum Northlander - you may be able to squeeze a bit more speed out of it, or a bit more hole shot, but it sounds like you're pretty close.

marine_man

[Northlander]

Ya I think Im good for now. Im as fast or faster than the otherguys running the same rigs. Ya more speed would be nice but what will it save me a couple minutes in a day long tourney? Plus I just cant afford to play with props with the price of gas.

Man I need to win a tourney/contest just to get back some of my gas money.

[Random guy]

But if you do hit rocks then yes, I would not get SS. I don't know Red, so forgive me if I am totally off base. Good luck with whatever you get!

Red has few rocks in the shallows but I'm real good at finding them! The top of my boat only has one scratch from a over zealous warden feeling he needed to board me and measure fish in five foot seas but the bottom looks like I drove it down a gravel road so I am finding rocks. Plus I spend alot of time on the Rainy river also, and the rainy really has rocks.

I have had several marine techs mention to me that both sides of the gears in my trashed lower units had impact failure. What does this is that heavy Stainless prop takes longer to stop spinning before I switch direction and I can't wait the two extra seconds to let it unwind.

I was hoping it would show today but not so. Delivery service up here is spotty to say the least. Maybe tommorow.

Oh and by the way they now offer stainless props all the way down to fifty horse. Another thing to consider is a stainless is $300-$600 and this alm four blader is $100 clams, let it grind away.

[Random guy]

We have it figured out now.

I ended up with a four blade Solas prop from Solderblooms in a 12.75 x 17 pitch and it works great. The boat jumps out of the water and cruises at 41 with just me in it and 34-35 with a load on.

I can't say enough good about Jay at Solderblooms, he had different props for me to try on my doorstep the next day and worked with me on finding the right combo.

Way cool

[Northlander]

Johny Im glad Jay hookd ya up. 41mph with a alum prop isnt bad at all. What RPM's are ya running at WOT with that 4 blade?

[Random guy]

She is capping out at 5800rpm with just me in the boat and 5400 loaded.