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SUBJECT: # 27907: Dunk or Others_Wheel VS RPM?
Submitted by Saul (68.84.44.153) from NEW JERSEY on 8/15/2008 12:19:00 PM
Hey Guys,
Recently purchased a 22 ft Sea Hunt CC with a 150 Yam. 4 stroke. Can't get the rpms over 5,000 @ WOT under any conditions. Although I normally cruise at 3500 - 4000, I know this setup should reach 5500 - 6000 at WOT.
Dealer originally rigged the boat with a 13 3/4 X 17 wheel and I am telling him it should have a 14 1/4 X 18 (smaller pitch, and recommended by Yamaha) to turn the prop faster. He disagrees! I don't want to damage the engine!
Am I wrong?
Thanks,
Saul
- 8/18/2008 10:21:00 PM
Submitted by
Dunk from NJ says Yes, You Are Wrong.
Saul, you need to drop down in pitch to get the RPM's up. I'd say you need 15" pitch prop to bring it up 4-500 rpms. Then I would look into raising the engine on the transom. For every bolt hole up you can go you'll gain another 75-100rpms. I really don't want to send you down below 15" because when the pitch get's less than the diameter performance really goes the window..That's allot of boat for that 150 4 stroke.
When you are running at wide open can you trim the engine all the way up without the prop blowing out, letting loose? If you can it's too low on the transom. To find the right height you need to raise it one bolt hole at a time. Run it wide open then trim it up. When the prop starts blowing out at about 3/4 trim up its right.
