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Old 07-28-2013, 10:21 AM
  #1    
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Join Date: Mar 2013
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Default new prop update for pontoon 11p to 9p

I had and 11 pitch prop and was only reading 5300 for my Yamaha f70 (5300-6300 rpms). My top speed was 20mph with just me. I just got a 9 pitch and my rpms went up to 5800 and kept my mph 20 mph using gps. the performance is a night and day difference. with about 300 pounds more of people it drops to 5700 and 18mph. turns so much better while keeping my mph at 17 instead of dropping down 13. last prop I had to have it trimmed up above middle now its down past half way and I can actually feel it hook up better doing so. I'm on the lowest hole for the engine.

Overall I'm happy with the 9p mercury calc. says 6% slip compared to I think it was 16%. would still love to get up to 6300rpms. but according to mercury calculator I would only gain 2 mph with a 9p.

I would love to try a mercury spitfire but they only go down to 10 pitch but diameter is slightly less. You think it would help or hurt top speed?
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Old 07-28-2013, 10:31 AM
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I think 20mph is as fast as it will go. That seems like a good prop.
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Old 07-29-2013, 05:48 AM
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went from a yamaha pontoon series stainless to a solas amita 3. it orginally came with michigan 11p aluminum. when i got the boat 3 years ago i think the tach was wrong. it would read 6300 but when i got a new tach it would only read 5300. the new tach and yamaha SS propeller was got at the same time. tried the 11p michigan in case it was the yamaha prop but it read 5300 still.

I bought all new fuel lines and had the dealer go through everything because i didnt think it could be the propeller. hooked up to yammi program dealer even confirmed 5300. after going through 3 faria tachs that messed up on me the dealer put in a yammi tach. he said he never had anybody have so much problems with the faria tach. all other faria gauges work just fine.

After this summer ill do my three year maintanance and change the VST filter. that is about the only thing i didnt change.
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