Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: Yamaha 40 Prop Size

Posted by joehonee on 06/12/20 - 5:34 AM
#1

I hate to do this but I have another prop selection question. I have a new to me 1988 13' sport. I am going to pair a 1986 Yamaha 40 HP (3 cyl - 2 stroke) motor on it. From what I have read, most people would recommend a 10-1/4"x14" aluminum prop for this setup. The motor came with an 11-1/4"x14" prop on it. It was my understanding that the diameter is determined by the outboard and is not typically changed. Very little info available on these older Yamaha motors so I am wondering if what I have is correct or if I should go down to the 10-1/4"

Also, how do you folks feel about the under seat fuel tanks made by Moeller and others. Too much weight for the boat or worth it for the range. I don't believe these older Yami's were the most fuel efficient.

Thanks in advance for your help
Joe

Posted by biggiefl on 06/12/20 - 7:42 AM
#2

Yamaha is only going to have one diameter per pitch per prop. They are not going to offer a 10.24 and an 11.25 with the same 14" pitch for the same engine. They might have a 10.25 but that is for a smaller engine, etc. 14" seems a tad on the small size but that depends on the gear ratio. My 35 OMC ran a 10x13 at 5500. My 40hp ran a 11.25x17 SS at around 5500. My 40 Suzuki runs a 11.25x16 SS at 5800. The suzuki prop is the same SS Rapture prop my OMC ran, I just had a lot of cup removed to get the rpms up.

Posted by Phil T on 06/12/20 - 9:11 AM
#3

Actually most prop people will recommend a stainless steel prop.

Recommendations for the 13 Sport with a Yamaha 40hp 2-stroke include the Yamaha Performance Series or Turbo Hot Shot in 10.5 x 12.

Edited by Phil T on 06/12/20 - 9:15 AM

Posted by joehonee on 06/16/20 - 6:36 AM
#4

Thanks for the help