Pontoon Boat & Deck Boat Forum

I want to put a ss prop on my boat. I currently have a 13 1/4 x 17-K aluminum. Seems to be propped correctly. Can't remember what my top rpm range is supposed to be but I'm pretty sure I knew at one point and it was correct. I'm not holding out hope for a great performance gain, it's just something I want to do. Would I order a ss prop with the same specs or should I opt for somthing different because it's going to handle differently?

I am not an expert, In fact I'm still looking for a ss of my own. But I started with a 15 1/2 x 15 aluminum and tried out a 14 1/2 x 15 SS (Yamaha Reliance --- Oh baby!!!). Had all around better performance.

So I'd guess that your diameter will change at least.

17p on a 115 seems like a lot. You really need to know exactly what your WOT and speed are before hand. I run a 15x15p Enertia on my 150 and get 6000-6100rpm at WOT which is perfect.

JohnO wrote:I am not an expert, In fact I'm still looking for a ss of my own. But I started with a 15 1/2 x 15 aluminum and tried out a 14 1/2 x 15 SS (Yamaha Reliance --- Oh baby!!!). Had all around better performance.

So I'd guess that your diameter will change at least.

John O specifically what was the differences> I have the yamaha 15.25x15p aluminum on a 150 yamaha 4stroke. I am wondering what difference a SS prop would make. Right now at 5700 rpm (WOT) I am getting 37.5 mph. Would like to spin 6000 to see if I could hit 40

What do you think???

Schmir, from what I understand the same prop in SS will spin a little less rpm's, thus you would need to go smaller, but keep the same pitch - I think???

Rick, When I picked up my boat, it had a Yamaha 14 pitch prop, and it was running about 36 mph @ 6200 rpms--up against the rev limiter.

I swapped for the Reliance 14 1/2" x 15 pitch prop on my F150, and I'm exactly @ 40 mph and 6000 rpm's. The Reliance 15 pitch would also probably be your best prop.

As far as the boat and prop in question, a little more information needs to be given--like speed and maximum rpm's with a relatively light load and the boat fully trimmed out. With 115 hp, a 17 pitch prop would indicate that the boat's far below a 5800-6000 rpm redline. With this information, better advice can be submitted.

Well, I have been getting 6000 rpm with the current prop. It's a tri toon with strakes. I can get to 30mph with the gps now as long as I have less than 6 people. Once I get over that I can't get the boat to "plane out". It pops up pretty good though as long as I'm not too loaded down. From looking around on the internet it looks like the Yamaha pontoon performance series 14x13 would be a good place to start. Does anyone have any experience with this prop or any other props to try?

IMHO, I think a 13p prop would be too small if you're getting 6000 rpm out of your 17p prop you have on there now.

I am amazed that you are getting 6000 with a 17P?? On my 115Merc the best I could get with a 13P was 5200 rpm so I went to an 11P to get the 6000 rpm. Best speed was 28 mph.

Just shows how different 2 boats can be. Mine btw was a 22 ft tritoon with strakes

Question which hole is your engine mounted?? I think my engine was too low but never bothered to change it. With my new engine - 150 Yammy I am in the second hole and think it is still too low. I am going play with this one before I reprop.

rbiederwolf wrote:I am amazed that you are getting 6000 with a 17P?? On my 115Merc the best I could get with a 13P was 5200 rpm so I went to an 11P to get the 6000 rpm. Best speed was 28 mph.

Very interesting. My tritoon without strakes runs 6,200 with a 13p prop on my 115 Merc 4-stroke. But only 24 MPH at best (but that's at 5,000+ feet elevation).

2nd hole down from top out of 4 holes. Unless tach is screwed up, I think its propped correctly. Motor sounds right to me. As in it doesn't sound bogged down or anything like that. Who knows, maybe I just think it sounds right because it's nicer than my last boat.

BobG wrote:

rbiederwolf wrote:I am amazed that you are getting 6000 with a 17P?? On my 115Merc the best I could get with a 13P was 5200 rpm so I went to an 11P to get the 6000 rpm. Best speed was 28 mph.

Very interesting. My tritoon without strakes runs 6,200 with a 13p prop on my 115 Merc 4-stroke. But only 24 MPH at best (but that's at 5,000+ feet elevation).

Not to Hijack the thread, but this is why I started the performance thread. Thought it would be great source of info to be able to scan in one place for either engines or boats of interest. In other words, if you had a 115 Merc 4 stroke, you could do a quick scan, and see who has the similar engine. From there you could check out their set up and performance to compare to yours or if you were buying a new/used boat , it would give you a reference point

I have a 27' South Bay with a 115 4S and a 13p Prop. 24 is the best I can do as well (at 6200 RPM's). I have lift strakes on the inside as well. If I try to trim up even the least bit, it cavitates real bad and the prop stops pushing. I am shopping around for a stainless to see if I can get a little improvement.

schmir wrote:I want to put a ss prop on my boat. I currently have a 13 1/4 x 17-K aluminum. Seems to be propped correctly. Can't remember what my top rpm range is supposed to be but I'm pretty sure I knew at one point and it was correct. I'm not holding out hope for a great performance gain, it's just something I want to do. Would I order a ss prop with the same specs or should I opt for somthing different because it's going to handle differently?

A good source for Yamaha Outboard/prop info is here on the Yamaha Outboard web site http://www.yamahaoutboards.com/owner-re ... -bulletins I used it extensively when buying a new pontoon about 5 mos ago. I wanted at least 40 mph at wide open throttle on a 2013 22' Southbay with Trifecta Package (tritoon, lifting strakes, under skin, power steering). So I ordered the F150 Yamaha with Reliance 14-1/4 x 17 SS prop. With 15 hrs on the new toon, it will do exactly 40 mph (gps) with two adults, 50 plus gallons of fuel and lots of gear. This correlates very closely with the performance data listed on the Yamaha web site.

Your 115 hp motor has a 2.15:1 gear ratio, in comparison with a F150's 2.0:1 gear ratio. If you had the same slippage that I'm experiencing, you'd be seeing 37 mph with a 15 pitch because of your lower gear ratio. You're far below 37 mph even with a 17 pitch prop, which indicates you may have really high slippage or excessive drag.

Are you getting your nosecones out of the water at top end? Is your boat fully trimmed out when you're @ 6000 rpm's? Is your tachometer accurate? Is your engine at the correct height on the transom?

You've got me stumped a little, as I would think your engine couldn't push a 17 pitch prop close to 6000 rpm's. I know you live in an incredibly beautiful heavy agricultural area, but are there any prop shops or marine dealerships that are exceptional at setting up pontoon/tritoon boats in your area? You might normally use a 14 pitch prop with your engine/boat combination.

I would be looking for a propeller seller that'd let you take 3 propellers of different pitchs to the lake--and return the ones that are unsuitable.

Good Luck!

Well, I'm certainly not that technical when it comes to gear ratios and prop pitch but maybe the prop is part of my problem. When I have a light enough load that I can get the boat to plane out on the strakes is when I can get to 30mph and have a seemingly correct rpm. Now on the other hand, if I can't get it planed out, I'm probably only running 20-23mph at best. Have not really paid much attention to the rpm under that scenario. Just assumed I had too much weight to do any better. So with a lower pitch I might get better performance with a greater load but won't get as good of a top end with a light load?