140hp Evinrude 23.5ft tri-toon need prop advice

[David P.]

I have a 1991 Evinrude E140TLEID on a 23.5 tri-toon, 2006 model. I think the boat mfg is long out of business. It is Mid something. The boat is about an hour away....I can get more details on the boat if necessary. My son broke a blade on the prop so I need a new one. Typically there are 3-4 of us on the boat without too much gear. We don't pull a tube or go fast at all really. We typically cruise around 3,500 rpm on a deep water lake in middle TN. We don't get great gas mileage. It has a 2411-133-17 prop on it. 13.25 diam 17 pitch 13 spline from what I can tell. I read that a 4 blade can be helpful for loading and unloading large pontoon from the trailer. Not sure if I have the right prop or if there is a better prop for what I do to either improve performance or improve mileage.

 

[NYBo]

Welcome to iBoats! :welcome:

We need more details: RPMs at full throttle, recommended maximum RPMs according to Evinrude, speed at full throttle (preferably by GPS).

 

[David P.]

Thanks so much Bob -
Almost half of one of the blades is broken off. I'll be up at the lake this weekend. Will I get accurate information with the prop that badly damaged? Unfortunately the speedometer doesn't work and we've not checked the speed by GPS at this point. We're starting our second season with the boat. Our local Evinrude shop says 5500RPM is what the max RPMs should be. He says 30mph is pretty typical top speed for a 24 foot tritoon. I do a lot of troubleshooting so I certainly understand you needing more information. Let me know if 30mph and 5500rpm is enough to get us by or if I need to take it out with the damaged prop? The old gal doesn't get to go full throttle very often so if you tell me to get her out with the damaged prop and run her I'll look forward to that! Thanks again!

 

[ahicks]

If the old gal doesn't get full throttle often, I fail to see the point of spending any more money than necessary for a prop. If you can find a 4 blade for the same kind of money you can a 3 blade, then maybe you can justify that move. Unless you spend a lot of time maneuvering, I doubt seriously you'll notice the difference when loading/unloading the boat original prop vs, new, no matter what style the new prop is.

Regarding the "right" prop, if the 17" pitch prop is (was) turning up 5500 rpm max, it sounds like that prop "used to be" the right prop. I'd just replace it and be done with it. Keep life simple!

 

[David P.]

Sorry if I wasn't clear. I don't know if 5500 rpm runs at 30mph. That's what the shop said it should be if the prop is the right prop.

 

[David P.]

I was just rereading what I had posted. I left out a critical piece of information. The previous owner of this boat bought the motor used off of a Runabout and put it on the pontoon without any verification that the prop was the right size or pitch. So the prop that's on there cannot be assumed to be the right size

 

[ahicks]

Well, 17" did sound like a lot of pitch for a pontoon boat.

Is there any chance a local marina might lend you a used prop long enough to allow you to get a tach reading?

With no tach reading, best case is going to be a only guess (with a hint from the marina guy suggesting a 30mph max speed), with nothing but a little experience to base it on. You mentioned you aren't pulling anything and max performance was not important to you. That in mind, I'm going to guess a 15" prop might be closer than the 17 was, looking to error on the safe side to keep rpm's safely in check. A 13" prop would be my next choice, based on the fact you have a tri-toon, without lifting strakes. If the boat is equipped with lifting strakes, I'd stick with my 15" guess.

 

[David P.]

I took the boat out this morning and it ran 23 miles per hour at 7000 RPM. It ran a 18 miles per hour at 5700 RPM. And it ran 7 miles per hour at 3700 RPM. I tried to upload a picture of the prop so you can see the damage

 

[David P.]

So my son just told me that sitting still with the motor off the tachometer shows 1600 RPM. Seems like there was not much right about this old boat that I bought

 

[jimmbo]

Well perhaps you need a new prop, one blade is partially gone. Might make a tad difference

Your engine WOT range is 5000 - 6000

 

[David P.]

Yes, understanding I need a new prop. That was my original post. Nothing on this boat appears to have been right so I need some help identifying the right prop. Thanks

 

[Sea Rider]

If needle tach doesn´t return to 0 when engine is turned OFF the tach has issues. Get a new one to start spot on prop maximization and dial a prop that makes the engine to rev 5.5K if prefer slight more top end speed or max 6K if prefer better hole shot, you decide.


Happy Boating

 

[ahicks]

I'll be less candid.
Holy cow. How can you expect to get ANY useful info running a prop with 1/2 a blade missing? Even attempting to do anything but get home with a prop like that is a BAD plan that will gain no useful info.

As far as the tach, a outboard running over 5k with half a blade missing is probably shaking the boat so bad, the tach has no chance of providing accurate readings.

Running that prop again could cause damage in excess of the price of a new prop (125.00 or so). Just go get one.

 

[Sea Rider]

Now the dilemma is : as have not made any previous wot rpm water test as loaded on flat water cond won't know if current prop pitch performed spot on or not. Will need to buy same new prop or other pitch prop as a starter and then go from there fine tuning a prop for OB to rev to it's full wot rpm range. What's your next step ?

Happy Boating

 

[David P.]

Thanks Sea Rider. I appreciate you following me through this troubleshooting journey. Since the previous owner had so much that wasn't right about the boat I don't place much faith in the 13.25" diam 17" pitch prop he had on it. My son is going to get by the boat this week and find out what size tach face it has on it. If there's a tach that has a solid reputation and doesn't break the bank I'll get a tach to put in next weekend. Based on what all I have read, been told, and researched I am thinking that I'll start with a 13.75" diam 15" pitch. If I can find a 4 blade for not much more than a 3 blade I may give that a shot. Other than out-running a storm I am not very concerned about the top end performance. I don't care at all about the hole shot. Really, I just want to be able to cruise at a reasonable speed without burning through more gas than necessary.

 

[Sea Rider]

You're welcome sir,

Firstly install a good tach, test current 17 pitch prop on a wot run on flat calm water cond. Report max wot rpm achieved as loaded. Can go from there with a larger pitch if OB is truly revving 7 K.

Other issue to know, how loaded do you usually like to go boating. On a boat load is a natural rpm killer which needs to be compensated in order for OB to run middle to max wot rpm range factory stated.

Happy Boating

 

[NYBo]

Y test current 17 pitch prop on a wot run on flat calm water cond.

I disagree with this part of the post. The current prop is so badly damaged, no good can come from running it again. In fact, it is possible it is so unbalanced that it could damage the prop shaft seal.

 

[David P.]

I ordered a prop. I will install this weekend and post an update. Thanks guys.

 

[Sea Rider]

If current prop is so damaged as to test it, which new diam/pitch, number of blades prop did you ordered as a starter prop ?

Happy Boating

 

[David P.]

I went with Solas 3413-138-15 PROP S/JE AL4 4S/V4 15. But, after checking everything and having the guys at the boat shop confirm it didn't fit. I'll call them in the morning. It was like the internal part that was pressed in place was backwards or something. I was able to work on some other areas of the boat that needed attention so it was not a total loss of time with the boat.