Bob Landry

R180/Yamaha 115 Prop Size

19 posts in this topic

To you guys who have this configuration, what pitch prop did your boat come rigged with? The performance results published by Yamaha with this motor and the same boat shows they ran their test with a 17p prop. High end of the operating range for this motor is 6000RPM. Mine only hits 5400 and it came with a 14p prop. With a 14p prop, this motor should be throwing rods through the block at WOT. I confirmed motor mounting holes and height of the cavitation plate above the bottom of the hull and it's identical to their test boat. Ran my checks weighted almost exactly as Yamaha did it and something's not right. It's going to the dealer Monday. I'm thinking the throttle linkage isn't set right, but I don't know why it would have a prop that is so for off from what is normally used.

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I have a 2016 R180 with the yamaha 115. Mine came factory equipped with the 14 pitch aluminum prop. I don't recall what the diameter was, as I exchanged it for a Solas stainless 13 1/2 x 15 pitch, model# 3431-135-15,  new saturn model,  that the dealer carried. This was recommended over the yamaha stainless, which is 2x more in cost. The exchange occurred prior to taking delivery of the boat, so I did not run it with the 14p prop. When I lake tested the boat after break-in, the 15p solas turned 6300 rpm with 2 adults and full of fuel. This achieved 38-39 mph per gps and speedometer. This was on calm water at optimum trim.  The rpm range for this engine is 5300-6300. Pre 2016 yamaha 115 had 6000 rpm as top of range. I thought that I might to be able to turn a 17 pitch solas and gain some top speed, so I purchased a 17p solas stainless, model #3431-133-17, which is 13 1/4 x 17. With the same load as above, I was able to turn only 5700 rpm, with no gain in top speed, which was a disappointment. I have since added a second battery, and often run with the live well full, since I mostly fish offshore. This extra weight has dropped my wot rpm to about 6200. Therefore, I have concluded that the 15p is the best for me. My brother also has an R180 with the 115 yamaha, and using this prop with good result. With regards to mounting height of engine, I cannot see the holes, as they are full of caulk. It appears that it would be in hole #2 from top to bottom. I don't, think that a higher mount would have a good result. You might pick up a little better top speed and rpm, but I think that cavitation would become excessive. The solas prop appears to be very good quality. The cheapest source I found for it was Dan's Discount Props on the internet at $224.95. Trying to find the best prop for your application can be a pita and expensive.  Hope this helps!

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The prop Yamaha used for their tests was a Deep-V which has been discontinued. From the info I have received, Robalo tested he R180 with the current 14p prop and decided that was the best one for this particular boat/motor. It's interested that by going up an inch in pict increased your WOT RPMs when that should have actually reduced, considering you kept the same diameter. Every prop "expert" I've talked to has a different recommendation so I'm really confused at this point.

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The same pitch and diameter in a particular brand will not turn the same rpm as that of another brand in the same size,  due to difference in design, surface area of blades etc. Aluminum vs stainless also makes a difference. Stainless props often have some degree of cupping at the prop edge to decrease slippage, which improves efficiency. The more a prop is cupped, the more it will reduce rpm at a given pitch. Props designed for higher speed boats typically have the most cupping.  Aluminum props typically have no cupping, and the blades reportedly flex some under load and are thicker.   Stainless do not flex. The solas new saturn has some mild cupping. These variables make comparisons difficult. When I exchanged the stock 14p yamaha  aluminum prop, the dealer, using a solas conversion chart, initially installed a 13p solas stainless on the boat. Prior to me taking delivery, the dealer lake tested the boat with this prop. At wot, the over-rev limiter was reached, so they put the 15p on it when I took delivery. This has proven to be a good choice for me. I think most will agree that at wot, you should be towards the higher end of the rpm range. For this application, ideally around 6000 -6200 rpm.

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All good info and I understand completely. At this point, I'm not sure that the throttle linkage is adjusted correctly and that the motor is getting the fuel supply needed to hit top RPM. I only base that on the fact that that it shifts rough going in and out of gear, both in forward and reverse. I may be erroneously comparing it to the shift/throttle linkage on my Seaark CC/Etec rig which is butter smooth. At any rate, my dealer is going to go through it. Having a motor that is capable of 6300 at WOT and that only hits 5600 doesn't work for me. I will seldom run at WOT but if it isn't right on the high end, it's not going to be right in the range that I usually drive it. Once I know the throttle is set correctly, then I can start looking for why the RPM won't get up there. That is assuming the throttle adjustment isn't the problem. I have to start somewhere, otherwise I'll end up with a closet full of props that didn't work and I still won't have a boat that runs right.

Yamaha's website and performance test data isn't any help either. They did a test with the 115HP motor on a R180, but the test is from 2013, using a 17" pitch prop that has been discontinued and a 115 HP motor with an operating range of 5000-6000RPM. That really makes it hard to compare apples to apples.

 

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I would contact Ken at propgods.com he deals with these problems everyday and I have found him very helpful, plus also he has a prop testing program.

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You didn't mention the WOT speed you achieved, but I would think, as you do, that a 14p prop of any brand, aluminum or stainless, should obtain substantially higher rpm than 5400.  Before you make any prop decisions, your engine needs to be checked for proper function. 

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37 minutes ago, kpate said:

You didn't mention the WOT speed you achieved, but I would think, as you do, that a 14p prop of any brand, aluminum or stainless, should obtain substantially higher rpm than 5400.  Before you make any prop decisions, your engine needs to be checked for proper function. 

If I remember correctly, it ran 34 MPH @ WOT with me and another person. I'm going to run it again this weekend and record some numbers for my dealer.. 

My dealer lake tested it before delivery and claims it hit 41 MPH but I'm doubting that.

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I would suggest that you make sure that your motor is optimally trimmed out at wot. If you had it trimmed way down, this would result in lower rpm and speed.  If everything is working properly, it should certainly be faster with higher rpm.

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To you guys with the newer boats, wat pitch would the prop be on the stainless steel prop upgrade for the R180/115? This would be for the newer motors that run in the 5300-6300 range.

 

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I did a little more controlled testing today. The wife and I, a cooler, and the two Yorkies(negligible weight) went out this AM. The lake was smooth, no wind. I ran it trough all of the RPM increments trimming it out for each speed. I was able to hit a WOT RPM of 6000 and 38 MPH. I do have a bimini, but it was rolled up and cased. The frame and booted bimini still stands upright so I figure I got at least a little resistance from that. 5000RPM was 30 MPH and all of the other checks were pretty much balanced out in the 500 RPM increments. Add to that the reduction in RPM that occurs in warmer eather, and it seems like the motor is propped correctly and running the right speeds. The prop size, RPMs and speed make a lot more sense now that I know this motor has an operating range 300 RPM higher than the one in the test results I read on the Yamaha site, plus them using a discontinued 17p prop.

We did have a friend and her two teenagers join us later in the day, and I ran through a couple of the RPM increments again. With three additional bodies in the boat i only lost 3 MPH. 

Now to start looking for a stainless prop.

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On 9/28/2017 at 0:28 PM, kpate said:

The same pitch and diameter in a particular brand will not turn the same rpm as that of another brand in the same size,  due to difference in design, surface area of blades etc. Aluminum vs stainless also makes a difference. Stainless props often have some degree of cupping at the prop edge to decrease slippage, which improves efficiency. The more a prop is cupped, the more it will reduce rpm at a given pitch. Props designed for higher speed boats typically have the most cupping.  Aluminum props typically have no cupping, and the blades reportedly flex some under load and are thicker.   Stainless do not flex. The solas new saturn has some mild cupping. These variables make comparisons difficult. When I exchanged the stock 14p yamaha  aluminum prop, the dealer, using a solas conversion chart, initially installed a 13p solas stainless on the boat. Prior to me taking delivery, the dealer lake tested the boat with this prop. At wot, the over-rev limiter was reached, so they put the 15p on it when I took delivery. This has proven to be a good choice for me. I think most will agree that at wot, you should be towards the higher end of the rpm range. For this application, ideally around 6000 -6200 rpm.

Which series Solas prop did you end up with? Also, what did you end up with for WOT RPM since you went up an in in pitch with the SS prop?

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I ended up using the solas new saturn 13 1/2 x 15 stainless, model 3431-135-15  which turned 6300 rpm, optimally trimmed,  full of gas, one battery, and 2 adults. Speed 38-39 mph. Solas makes props in 2 inch pitch increments, so they don't make a 16p in this model . Following the rule of thumb that in the same brand/model prop, each inch of pitch making a difference of 200 rpm, I thought I could turn a 17 pitch solas 5900 rpm and pick up 1-2 mph. I could turn it only 5700 and did not gain any speed. Knowing that for fishing I would be heavier, the 15p was the obvious choice. With an additional battery and loaded for fishing, I can turn 61-6200 with the 15p. Better acceleration with the 15p vs 17p. I believe the yamaha stainless are in even number pitch increments, 14p, 16p etc.  and cost around $450. I would like to see what the 16p would do, but am not willing to part with the $ to find out.  Some robalo R180 packages have the yamaha stainless prop equipped as an option, but I don't know the pitch. When I was trying to make a decision when my boat was new, I sought forum member input  about prop experiences, but got no response from 115 owners.  My brother purchased a 2016 R180 with 115 and selected the 15p solas new saturn based on my experience. His performance data is consistent with mine. He does have a trolling motor and 3 batteries, so he is about 100-200 rpm and 1 mph slower than me. I also have the bimini top, and it was in the upright position. I thought that maybe having the stainless prop, I could get 40 mph, but not so. Since you are able to achieve 38mph at 6000rpm with the aluminum, I am not sure spending more $ for a stainless prop to get 1 mph more is worthwhile. 

Edited by kpate
additional information.

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I just heard back from my saleman about the SS prop upgrade for the 115. It's a 13 1/8X16 SDS(whatever SDS means) and retail with tax is $788. I can tell you that's not going to happen, but I was curious what the opgrade prop was. I guess they had to reduce the diameter to run it with a 16" pitch. Going to look at Solas and Power Tech. I have a PT on my Seaark/Etec and really have been happy with it.

 

Also forgot to mention, I took it in to the dealer this AM to get the shift linkage adjusted. it was a little clunky moving in and out of gear. I also asked him to check to see if I was getting the full range of throttle movement and I wasn't. He adjusted that also, so now I'm waiting to run another test on it to see f that picks up any RPMs.

 

This prop thing has really turned out to be an education.

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The price of the yamaha prop is absurd. The power tech and solas are nice props. Since I know how a solas will perform, I would be especially interested in your result if you got one of the power tech props.  

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I upgraded to the 150 hp, I have a 17" solaris off my previous  2013 -115hp, for sale on Rochester ny craiglist IT ran perfect nearly 40mph 5800 rpm.

 

 

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7 hours ago, wildoats said:

 

It will not work for this application, as this entire thread has been about the 115s that have been made after 2014 and have the increased operating range.

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ah,  sorry ,,...did not realize they changed the 115 in 2014.

 

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