Pontoon Boat & Deck Boat Forum

Is it better to go 22mph at 5100 or 21mph at 6k rpm? The difference between a 14. 11 and a 14. 13 pitch. I have a 2004 50 horse Yamaha on a 2019re sweetwater.

I would say you need a 12 pitch prop. Get the rpms around 5500. Whats the max rpm on the motor? 2 or 4 stroke?

Manufacturer says optimum mom is 5K to 6K and it's a four stroke.

I have a yamaha 75 four stroke.. and I believe the specs show the rev alarm will sound at approx. 6200 rpm's. My boat wide open is turning just a hair under 6K rpm's.... A few years back I changed props and she topped out at around 5K rpm's and the guys on this forum told me I was over propped... So I went back to my original prop where she runs about 23 mph just under 6K. Hope this helps.

What did you do with the prop? Can they be returned? No blemishes on mine. Used once.

Yea close to 6000 as you can get it with a light load. Toons are harder to get max rpms out of them. You lug the engine if you only turning 5100 rpms.

I can tell you that at 5,100 rpms you are saving gas big time over 6,000 rpms.
I would only run the smaller prop for when you have 10 people on your boat.
BTW, I have the exact same situation on my Merc 150 and base my info off my Mercury smart craft gauge.

[quote="Otisville"]What did you do with the prop? Can they be returned? No blemishes on mine. Used once.[/quote]

I returned it to marine shop where I bought it. Called him up and told him how the new prop was only cranking out about 5k rpm's and told him I wanted to go back to the original pitch prop. He ordered me a new one and it was at his shop like 3 days later..

Make sure your motor height is correct. If it is not you get strange results with different props.

What is the simple science of engine height? How I check? The engine has been at the same height for years. Thx

It's a good idea to have a spare prop along with hardware and floating prop wrench. 5100 rpm is a little low though.

[quote="Otisville"]What is the simple science of engine height? How I check? The engine has been at the same height for years. Thx[/quote]

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http://nodakangler.com/forums/showthrea ... ine-height