Optimum Propeller 26X - 50 hp Yamaha

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Late2sail
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Optimum Propeller 26X - 50 hp Yamaha

Post by Late2sail » Tue Jul 10, 2018 12:41 pm

I'm sure this topic has been covered, but have struggled to find info particular to my question through search.
I'm wondering if anyone has experimented with prop sizes/pitch/# of blades to find the optimum "all around' best prop for a 50 hp 4-stroke set-up. I need to take my boat out to collect more data - i.e. max speed and rpm at WOT with ballast empty / full. I recently took it out an achieved max speed 14 mph (I believe my guage is mph rather than kph)? Our boat is kept at a lake and has minimal gear on board. Passengers are typically my wife and I (285# total) and 2 kids (160# total). Usually smooth to light chop. current propeller is Solas YC 25 14 3311-121-09 Any help would be much appreciated.

Snowdancer
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Re: Optimum Propeller 26X - 50 hp Yamaha

Post by Snowdancer » Sat Aug 08, 2020 9:15 am

I would like to know your propeller recommendation for the 26x 50 hp yamaha. Retired my 50MD tohatsu 2 stroke for a vibrating undersized Yamaha t25c .

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Herschel
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Re: Optimum Propeller 26X - 50 hp Yamaha

Post by Herschel » Sun Aug 09, 2020 8:37 pm

Sorry to take so long to notice this thread. When I replaced my '98 50 h.p Merc and had my new Yamaha 50 h.p. installed on my 26X back in 2013, I had been experimenting on the Merc. with 14 in diameter props with three different pitches (10, 11, and 13), finally settling on the 10 to help get the Merc engine RPM's up close to the prescribed range at WOT. Frankly, I was a little tired of constantly wondering if I had the right pitch going. When I asked the Yamaha dealer about the pitch of the new prop for the Yamaha 50, he said he had a perfect prop for the boat. He was a dealer in Trader pontoon boats, and he seemed to be really knowledgeable, so I went with his recommendation. He put on a 14 inch, aluminum, 11 pitch prop, and I have been totally happy with it. I top off at 15.3 mph with my wife and copious gear aboard. It runs in the mid 5000 revs at WOT, so I am happy on all counts. And my Yamaha has never failed to start in the past 7 years except one time in the first year when I got some bad gas. And that is my story and I am sticking to it. :P 8) :D

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Tomfoolery
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Re: Optimum Propeller 26X - 50 hp Yamaha

Post by Tomfoolery » Mon Aug 10, 2020 5:14 am

Herschel wrote:
Sun Aug 09, 2020 8:37 pm
When I asked the Yamaha dealer about the pitch of the new prop for the Yamaha 50, he said he had a perfect prop for the boat. He was a dealer in Trader pontoon boats, and he seemed to be really knowledgeable, so I went with his recommendation.
This comes up every so often - pontoon boats seem to be the best model for plugging into online prop selector programs for our hybrid boats.
Tom
Be seeing you . . .

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Herschel
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Re: Optimum Propeller 26X - 50 hp Yamaha

Post by Herschel » Mon Aug 10, 2020 6:43 am

Tomfoolery wrote:
Mon Aug 10, 2020 5:14 am
Herschel wrote:
Sun Aug 09, 2020 8:37 pm
When I asked the Yamaha dealer about the pitch of the new prop for the Yamaha 50, he said he had a perfect prop for the boat. He was a dealer in Trader pontoon boats, and he seemed to be really knowledgeable, so I went with his recommendation.
This comes up every so often - pontoon boats seem to be the best model for plugging into online prop selector programs for our hybrid boats.
typo: Tracker boats not Trader. sorry. Herschel

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Re: Optimum Propeller 26X - 50 hp Yamaha

Post by wakataka » Mon Aug 10, 2020 3:06 pm

There are two versions of the 50hp Yamaha, the F50 and the T50. The T50 has a lower gear ratio and can turn bigger props. It's the better engine for a 26x, but for some reason many 26x boats (including mine) had the F50 installed. So the discussion below is only relevant to the F50 version.

I've recently been trying different Solas Amita 3 blade props on my F50 trying to find the best option. The previous owner had a 11.6 x 11 prop mounted. The engine was over-propped and would only turn up about 4,400 rpm. I switched to a 11.8 x 10 which put the full throttle RPM up to about 4,900, just below the Yamaha recommended minimum of 5,000. I then tried a 12.2 x 7, which allowed the engine to turn up to 5,400 rpm but the top speed was decreased just a bit from 14.5 to 14.1 knots. The bigger problem was at low speed cruising (~2,500 rpm) I lost half a knot. Also it seemed that the prop wasn't loading the gears enough. At rpm below about 1,500 there was a loud and annoying whine coming from the gearbox. I rarely run the boat at full throttle, so this noise and inefficiency at low speed was a deal killer. I switched to a 12.2 x 8, which I'm happy with. The speeds and RPMs are almost identical to the 11.8 x 10, there seems to be slightly more thrust at idle, particularly in reverse, with the larger diameter prop. I'm keeping the 11.8 x 10 as a spare. With either prop, I get full throttle speeds just a little over 12 knots with ballast and about 14.5 knots without ballast. This is with one person aboard and the boat loaded with several hundred pounds of cruising gear and fresh water.

Hope this helps.

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Re: Optimum Propeller 26X - 50 hp Yamaha

Post by Herschel » Mon Aug 10, 2020 7:59 pm

There are two versions of the 50hp Yamaha, the F50 and the T50. The T50 has a lower gear ratio and can turn bigger props. It's the better engine for a 26x, but for some reason many 26x boats
Went to my paperwork and confirmed that my Yamaha 50 h.p. is a T50 TLR. I think the TLR is similar to the Mercury High Thrust designation, but I am not sure.

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Re: Optimum Propeller 26X - 50 hp Yamaha

Post by wakataka » Tue Aug 11, 2020 2:02 pm

Yes. The T50 is a 2.33 gear ratio vs 1.85 on the F50. So the T50 turns a bigger prop and produces more low-end thrust. Same idea as the Merc Bigfoot. The T50 should be very good motor for the Mac IMHO.

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