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I have a "70" Wriedt Spoiler 16' with a Merc. 115hp on it. I was wondering if anybody knew of a good prop to get. Merc doesn't make a prob big enough for my application. The boat goes about 70 at 3/4 throttle then after that it over revs the engine.
I was looking at a torque shift but they don't make one for the 115hp mercs only for the bigger engines. Does anyone have any suggestions
[This message has been edited by Opie8565 (edited May 07, 2001).]
Opie, What pitch and diameter are you spinning now and at what rpm? Are you looking for all out speed or skiing? My first boat was a 16 foot Avenger with a 140 merc. It worked really good with a 23" clopper ( I want to say 13 1/2 " dia.). It would do a little over 60 mph @ 5800 rpm and pulled skiers out of the water all day long.
I'm running a 23" pitch and I'm going about 70-73. It's a 13.25" diameter. Even with this prop I have no prob pulling up 3 skiers. So all i'm worried about is getting some more speed so i can see how fast i can make this old crate move. That and not killing my engine cause Merc recomends only 5250rpm's and i'm pushing about 7000.
Opie,
Have you ever checked your speedo with a GPS? It sounds like you may be getting blowout. 7000 rpm with a 115 with a 23" prop seems way too high. Does it hold good then at a certain speed just lose bite? If that is what it is doing, you may need a nose cone. What is your prop shaft height? I imagine it can't be too high if you can pull three skiers out of the water.
My speedo is pretty close to being true acording to other boats. The problem is that my boat only weights like 750-850 lbs. As far as it over reving at a certain speed no it slowly over revs the more you push it. What do you mean by the shaft height? I'm pretty new to all this. We've had the boat since mid 80's but we blew up the Evenrude we had on it and this merc is just a power house compared to the old Evenrude.
[This message has been edited by Opie8565 (edited May 08, 2001).]
Don't get me wrong, I am no expert by any means. I am hoping somebody with some real experience will chime in here.
750-850 lbs is that bare hull or fully rigged and ready to go? If it is bare hull that is about average weight. My Daytona was a kevlar layup and the bare hull was less than 400 lbs.
prop shaft height is the relation of the centerline of the propshaft to bottom of the boat. Performance boats generally run close to even with the keel. Some above. Ski boats are generally lower. Your hull design and the type of prop will determine how high you can run the prop. Choppers and cleavers are common semi-surfacing props. The higher you run the prop the more rpm and typically the more speed.
Do you know anybody with a 26" prop? Michigan propeller makes alot of different props that are relatively inexpensive if you are using aluminum, but something still seems amiss.
What was the hp on the Evinrude and what prop did it have and what rpm?
That weight is fully loaded. As far as the prop shaft height it's set to were the boat isn't cavitating and where it's not too squirly.
We tried a 25" alum. and still had the same prob but we got a few more mph out of it.
Then Evinrude was a 125hp and we ran a Rampage 13.25 x 20 pitch. and we were pushing 6200rpm but it had some work done to it. We aren't sure all that was done to that.
Do you have a email address where I can send you a pic.
[This message has been edited by Opie8565 (edited May 08, 2001).]
The 14" diameter Choppers were made for the inline engines (though they have also been widely used on the early V-6s). The 14 1/2" came out later specifically for the V-6s. I think a 14" diammeter X 26" pitch Chopper will give you excellent speed and get your rpm down closer to where they ought to be. With this prop, even more speed can be gained by raising the engine so that the prop shaft is close to being even with the boat bottom (or slightly below). You will have to watch your water pressure at these heights, however, unless you add a low water pickup nosecone. Unfortunately, such a high height will really hurt trying to pull-up skiers. The only way to have the best of both worlds is to get a hydraulic transom jack that will let you adjust your height at the touch of a button. Such a jack will also give you some "setback" from the transom (4"-6" inches depending on which one you buy) that should also add to the speed. I have to say that 70+ with a 23" pitch "ski prop" on a 115 sounds almost impossible, but I certainly can't say for sure. Is your current prop a "thru hub" or an "over the hub" exhaust? The Chopper will be "over the hub" which means it will slip a lot coming up on plane (rev high real fast due to exhaust gases "blowing" over the blades) but then bite like crazy and take off. Make sure your transom is in real good shape if you decide to add a transom jack (may need to reinforce it some, but we can talk about that later). If you can get your hands on a small diameter 26" Chopper, I would try it.
Hey BillyD
I'm using a thru hub exhaust prop. and on this boat this motor seems to have a lot of tourque. I can take and hit the throttle real quick and take the whole boat out of the water. Thanks for you info I will look into the chopper.
Hello Guys,
I run a looper so I can't play but I did want to warn everyone not to machine a cast flywheel. Gordon (Monty Racing) did it to a looper and within a season it developed cracks. Jay Smith also said he wouldn't cut on a cast fly.
Crossflows will turn up but one thing all these guys(Bill Gohr,Acie&Gordon) agree on is the Accumlative Harmonic problem the crossflow engine has. At 6100 it fatigues the crank atthe flywheel end and breaks. Pass through that RPM so there's no frisbee flingin.
As far as the lean mix, I installed the Dial a Jets on mine to see if it will fix that problem. This thing is suppose to richen or lean the mix on demand.
I hope I'm not too late on the flywheel machining
Have Fun
hey opie,
check your tach at a dealer to see if it's right.i really don't think that 115 is turning a 23" to 7000.as far as the speedo goes the "it's close to other boats "isn't even close.all but the very best,HIGH $ speedos are wrong.i've got a 70 mph checkmate that the speedo is right on with the gps at 40,but says i'm doing 50 at 70 on gps(close.lol)borrow a hand gps and get that tach checked out
Opie, what's wrong son? Aunt Bee is gonna be real upset at you fer telling some tall tales again, you looking for a hickory stick son?
Be sure to tell your Pa(Sheiff Taylor) I said hi.
70mph with a 115, on anything, a piece of plywood, hahahaha, I outa slap yuo myself Opie! 7000 rpm, hahahahahahahaha, son!
[This message has been edited by HavasuBarney (edited June 25, 2001).]