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| I just picked up the new motor this weekend and took it out to break it in. I am trying to get this outfitted with a stainless prop and am in the process of trying them out.
The first prop I was loaned was a 3 bladed 19" pitch. The hole shot seemed pretty good, although we only could get this to 5000 rpm (max recomended in the manual is 5750). It is my understanding that for every 1" down in pitch I should gain roughly 200 rpm's. That being said, i would need appoximately a 15"pitch to get to the targeted rmp. My fear is that i would loose too much of top end if i went that route.
My question is would increasing or decreasing the diameter of the prop have a noticeable affect on rpm's? I'm guessing decreasing the diameter would help in increasing rpm's.
Does anyone have any thoughts on 4 bladed props as well?
The dealer is pretty helpful in regards to swapping props, although it helps me if i understand this too.
By the way this is a 115 optimax on a Ranger Cherokee (alumiminum) boat. |
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Posts: 2323
Location: Stevens Point, WI | If I am right, I believe your rpm's will go up once you have some time on the motor and it's through full break in.
Also, did you have the motor trimmed all the way up? Your rpm's will go up when you trim the motor up. Just for reference, you shouldn't be pushing your brand new motor full throttle until you at least have an hour on the motor. Not saying you did, but just wanted to point that out. The first hour you shouldn't exceed half throttle, except for getting the boat on plane, you then back off the throttle. Second hour, you can hit full throttle, but again, do not let the throttle sit in one position for more than 2 minutes, that is very critical. You are setting your o-rings in the motor and changing your speed is very important on break in.
Edited by Merckid 8/20/2007 3:01 PM
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| Yup, we didnt go wide open until we had over an hour on it. Motor was trimmed.
I was wrong the rmps maxed out at around 5150 or so, according to the manual the recommend running as close to the 5750 as we can. That being said I need to raise the rpm's by 600 somehow. Have about 5 hours on the motor as of now.
Thanks for your help with some of my other motor questions I asked in the last couple weeks, it has helped me out.
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Posts: 3514
Location: Elk River, Minnesota | Hi,
couple of things you may want to consider...
First, if the motor is mounted all the way down (bolts are in the top holes and the motor is flush to the transom) I would bet you can move that motor all the way up, or at a minimum up to the 3rd hole. This should gain you about 150 or so RPMs.
By doing this, you may find that you only would need to drop to a 17 pitch prop. Also, if by chance you get a chance to try a ballistic prop, you may find that you will have higher RPM's with the same pitch prop as the one you tried. And...at least from my experience, the ballistic hooks up really well.
with a little tweaking of the set up of the rig, I think you can get close to your max without dropping all the way down to a 15 pitch prop.
Good luck
Steve |
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Posts: 32958
Location: Rhinelander, Wisconsin | What brand motor, and what type is the prop? So much depends on that it's impossible to make a generalization. |
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Posts: 2323
Location: Stevens Point, WI | 55esox - 8/20/2007 2:54 PM
By the way this is a 115 optimax on a Ranger Cherokee (alumiminum) boat.
A 19 sounds pretty big for a 115 Opti. But then again, that's an aluminum boat so that probably would be ok. However, a 17 might do you good. I would think one size smaller should possible fix your problem. A three blade Vengeance would probably do it.
Did you have the boat rigged at Heckel's Marina in Eagle River by chance? I remember seeing a boat exactly like the one you are talking about? If so, Heckel's being a Ranger dealer, has to be pretty close to right on with where the motor is mounted, but then again, they do make mistakes. If you did get the motor at Heckel's, give Brian a shout, he's the service manager and one of the best that I know and have met!
Edited by Merckid 8/20/2007 4:57 PM
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| Thanks for everyones help and bearing with me on this. I admit I know next to nothing on this.
That being said, I am in Chicago now and the boat is stored up in Northern Wisco, so that makes it a little tough being so far away from it. I dont recall the manufacturer of the prop, but I will look into it. The boat is a 17.5 Ranger Cherokee with a 115 Mercury Optimax.
I will look into the hole settings and see what the dealer has to say. |
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Posts: 5874
| I'd try a 19 Laser II on that boat. Smaller diameter prop, but it is an ok prop for an aluminum boat. Put the medium or large vent plugs in it.
The best advice I can give is to call Ranger, and see what they recommend. They should have a history of that boat, and which props worked, and which didn't.
The other thing is to find a dealer that has a prop demo program. They'll have props you can try, and will hep you with it. They do expect you to buy a prop from them when you are determine the best prop for you boat motor.
Edited by Shep 8/21/2007 8:39 AM
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Posts: 215
Location: Twin Cities | To hitch on to this thread - I have a question too.
I have a 2007 150 Opti, on a Ranger 188VS - I can get up to 5200 RPMs, I have been instructed by many that the RPM target is 5400. From what I have read here it sounds like i need to drop my pitch by 1.
Can anyone recommend what style and pitch prop they use on a similar set up. Thanks. |
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| Yes the boat was rigged at Heckle's and we are dealing with Bryan. They have been helpful as of now with the props.
I'll give ranger a call to see if they have any info. |
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