GF-16/20 Nissan

Discussion in 'Prop Shop' started by tomahawk, Mar 11, 2015.

  1. tomahawk

    tomahawk Well-Known Member

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    Ok, I'm starting this thread because I'm getting conflicting opinions between some prop pros and my stupid buddies (A term of endearment ::) )

    The motor is an 09 Nissan four stroke. The AV plate is 1/2" above the flat bottom. The length is 15' 11" and it weighs around 350 to 450 estimated. The current prop is the stock aluminum 9.25D 9P that is pretty beat up.

    I was hitting the limiter at 25 mph @ 6200 rpm's at 3/4 throttle when I took her out this afternoon. With my wife in the boat there was no appreciable difference. When my wife and grown son got in the boat, I was still hitting 6200 at almost full throttle at 21 mph loaded.

    Powertech recommended a SRT3 9.5D 9P. They said the rake and cup is what it needs. I talked with Blair Propeller and Marine in Stuart and they recommended the same prop. I also used the Merc Prop Finder and it recommended a 9.25D 9P which is basically whats on there now.

    My buddies say no effin way it needs an 11p and maybe even a 13p.

    Obviously I'm more inclined to take PT's advice but I would like some of your opinions.

    Thanks
     
  2. Brett

    Brett > PRO STAFF <

    Merc 9.9 4 stroke. Factory prop was a 9x9
    I replaced with a 9x10 cupped
    Dropped rpms by about 300 according to my diagnostic tach.
    Works out to about 150 rpm due to 1 inch increase in pitch
    and 150 due to the extra cupping. Made a difference in hull speed and handling.
    Y'er buds may be correct as to what you need.
    Sounds like you need to drop about 700 rpm.

    [​IMG]
     

  3. cutrunner

    cutrunner Cert. Yamaha technician

    Whatever Blair proppellor says, take it and run with it. He does all my work. He really knows his $hit.
     
  4. tomahawk

    tomahawk Well-Known Member

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    Thanks Brett and Cut!
     
  5. tomahawk

    tomahawk Well-Known Member

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    I went with the Powertech recommended but upped the pitch to 10" over the 9" that was initially recommended and I'm glad I did. The top speed increased to 26.5 mph @ 5990 rpm and cruise at 20 mph @ 4800 rpm. If I would have went with the 9" I'm pretty sure I would have been into the limiter and that would have really pissed me off.;D That was with me and the wife. I didn't run it alone. I was hoping to get closer to 30 at wot but I'm still really happy with it.
    I even poled it a little today  :D

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