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aka: KSims1868
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Discussion Starter · #1 ·
I have a 20' SeaSwirl bay boat (center console).

I can get it just over 40 mph and around 5400 rpm WOT with a 140 Johnson V4 engine - Viper 21 pitch s/s prop. I can cruise all day at 30-35 mph turning about 4800-5000 rpm and it's running smooth in this range.

Does this sound about right? The guy I bought it from also gave me a nice Viper 19 pitch s/s prop and said he never got around to swapping them. Would I benefit from going to the 19 pitch?
 

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sea monkey rancher
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18,403 Posts
thats alot of boat weight for a 140. sounds like you are in the right rpm/speed range.

if you are usually loaded heavier , pulling skiiers, need more hole shot, etc. then try the 19 watch your rpms at WOT, about 5800 is plenty for that motor.

gps your speeds at 4000 and 5000 rpms and ck the diff.
 

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aka: KSims1868
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3,848 Posts
Discussion Starter · #3 ·
Forgot to mention...these speeds are GPS MPH and RPM from the tach on the dash.
 

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Gone Fishing
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12,003 Posts
Thats about right, the 19 pitch you will loose MPH and gain RPM.
I never go above 5000 RPM for any long period of time.
 

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aka: KSims1868
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3,848 Posts
Discussion Starter · #5 ·
Yeah - I've been sticking to cruising around 35 - 38 mph which keeps me just under 5000 rpm. Seems to be a very comfortable speed in this boat and the motor is purring just right (sounds just right) when turning that rpm.
 
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