Yamaha F115 prop pitch question

JonAllen

Recruit
Joined
Jul 5, 2012
Messages
1
My F115 per the manual has a full throttle operating range between 5000 and 6000 rpm, with max horsepower achieved at 5500. With a 17 inch pitch prop, it runs between 5000 and 5200. I understand that each inch of pitch decrease will likely change the rpm 200. My question is whether I should go with a 15 inch, where it would run between 5400 and 5600, or a 13, where I can potentially have the range up to 6000?
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,819
Re: Yamaha F115 prop pitch question

Don't know about 4 stroke outboards, but 4 stroke cars and 2 stroke OB's do best when at the higher rpms where the engine is under less stress, hence better performance, better fuel economy. I'd opt to run at the top end. Second thing this buys for you is in doing that, you reduced your prop pitch which helps your hole shot....faster and less stress on the engine.

Mark
 

smitty477

Seaman Apprentice
Joined
Dec 25, 2009
Messages
44
Re: Yamaha F115 prop pitch question

We has a Yamaha F115 for 6 seasons and quickly learned that you do not want to run that engine propped at the lower range. What is best is to prop the engine to reach 6,000 or as close to it as possible when fully loaded as it is used. You can find plenty of posts on what happens if you do not do this and lug the engines. These engines are quite happy running at higher rpm's but not lugging in the lower ranges. Please also consider if your engine mounting height, trim level and boat weight distribution is best for the performance you are after.
Hope this helps
 
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