missing top end speed

1987iroc

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I just bought my first Bennington 2009 QXI 2575, W/200hp Yamaha outboard, I love the boat but top speed is only 28mph, all the test I've read say this set up should do 35-40 mph, any recommendations on maybe prop size or anything else to try, I currently have a 19 size prop on it
 

MILO851

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Hi Gonna need little more info what RPM are you hitting and what pitch is the prop. I am assuming 19 is the diameter
 

BulldogsCadillac

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I'm assuming this is an F200, not a 200 SHO? On my SHO it was a Saltwater Series II 15x15 3/4 stainless, 41.8@5700 rpm.
 

Ben & Suzy

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I'm sure he means a 19p prop. Which model Yamaha 200 do you have? That will tell us the gear ratio. Current rpm's @ WOT?
 

1987iroc

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Its a 14 diameter & 19 pitch @5500rpms tops out@28 mph, with only 2 people and 1/2 a tank of gas

motor is a f200 Yamaha,
 

mtudb24

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Are you reading the speed of a Speedo or gps?
 

ronfl

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our 2550 rcw with a 150 optimax is hitting 32 mph WOT and turning about 5200 rpm. Just went to a 16' 13 Pitch to get RPMs up. I suspect I have a few more mph if I get propped right and the WOT RPM 5600 . If you go to Mercury marine website they have a great "choose a prop" test. You will need to know your RPM and prop size and pitch. I would think with the 200 HP you should be able to get close to 40 MPH with a light load. Like us you have a big heavy boat to start! http://www.mercurymarine.com/propellers/
 

ronfl

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I just bought my first Bennington 2009 QXI 2575, W/200hp Yamaha outboard, I love the boat but top speed is only 28mph, all the test I've read say this set up should do 35-40 mph, any recommendations on maybe prop size or anything else to try, I currently have a 19 size prop on it
I'm guessing you have the same problem I had with the motor being way over propped! I had a 15 P on a 150 and couldn't get RPM up to the 5600 to 5700 range factory says it should be. Good grip but no top end speed!
 

1987iroc

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Readin GPS, so pretty accurate, and I'm turnin 5500rpm so why so slow
 

DJMbrooks

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Are your toons clean of algae? I think you said you bought used. I have the same size boat, but w/ a 250. We left the boat in the water over the winter and lost a full 10 mph from algae growth. Once I got them cleaned up, she was back up over 40. I never would have believed it could cause that much drag, but it was dramatic!
 

1987iroc

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thanks doug, wow, sounds like i got some cleaning to do, great looking boat, mine is black and java too, i think im gonna pop for the double bim. top like yours next year,

...Did you use an alum.cleaner on the bottom of the toons?
 

Link

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1987iroc, there are some great posts on how to clean toons [depending on how fussy you want to be] and how best to maintain them. Use the search engine to find all the answers.

Personally I use a strong solvent when I take my boat out of the water in the fall. Touch them up again in the spring [inside storage] and then apply sharkhide. I may very occasionally give them a quick wipe down and I just use a cleaning cloth and the lake water with no detergent
 

DJMbrooks

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Yep. Just like Link said. I used the Sharkhide cleaner, followed by the protectant. When I had my boat serviced, I asked the marina to hoist up the boat and get the under side of the toons and then I did the rest. Honestly, though, just scrubbing them with a scotchbrite sponge and some detergent will get a lot off and make a big difference in the short run.
 

SEMPERFI8387

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I scrubbed mine good with scotchrite pad couple weeks ago (no Sharkhide) and ill do them probably two more times till waters too cold. I just anchor at island and wade around the boat and scrub a dub dub ........
 

Link

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Doug, what I used was more along the lines of acetone, takes everything off at the end of the year
 

1987iroc

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thanks for all your help guys, i will clean those tubes, but also want to try another prop size, anyway to tell what the gear ratio is on that F200 yamaha and any recomds. on what prop size and pitch to try??
 
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