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Old 13 August 2010, 17:17   #11
Country: UK - England
Town: Southampton
Make: Ballistic
Length: 7m +
Engine: Yam 225
Join Date: Jun 2010
Posts: 887
not sure id look at a boat problem to start with tbh, i used to teach from a 5.4 SR with a 50 (hull bunged up). Technique may be the issue.

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Old 14 August 2010, 02:59   #12
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Country: UK - England
Town: Southampton
Boat name: Hissing Sid
Make: Ross Smith Cobra
Length: 6m +
Engine: 200HP Optimax
MMSI: 235038046
Join Date: Jun 2002
Posts: 3,803
Originally Posted by roland.fisher View Post
50 on rpm meter (5,000 rpm I think) and top speed at about 38mph on the speedo, even with four or five adults on board.
It's a 4 stroke, yes?
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Old 14 August 2010, 04:31   #13
Country: UK - England
Town: Mighty Penryn
Boat name: Little Joe.
Make: Avon Searider
Length: 4m +
Engine: Honda BF50
Join Date: Aug 2005
Posts: 8,793
Has someone stuck a one infront of the fifteen on that Yam?
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Old 14 August 2010, 22:36   #14
Country: USA
Town: Oakland CA
Length: 3m +
Join Date: Feb 2005
Posts: 6,620
If it's an F115, you should be pulling 6000 rpm WOT with a "normal" load. So you're probably 3 or 4 inches long on pitch to start with. The range is (as I recall) 5000-6000, but optimally you want to be in the higher end with a lightish load (say, one or two people, and say half a tank of fuel.) Going a touch over isn't going to do much, but being low on rpm means you'll never get rated power out of the motor.

If you'll be doing a significant amount of skiing, you might want to have a second, even shorter prop for a better hole shot, but you don't want to use that for long distance running without skiers for risk of overrevving.

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Old 17 August 2010, 15:22   #15
Country: UK - England
Town: St John, Cornwall
Boat name: Ningaloo
Make: Ribeye 5.8m
Length: 5m +
Engine: Yamaha 100hp
Join Date: Mar 2006
Posts: 99
Dare I say it... may be the skiers technique. Used to monoski at 15stone off a Fletcher bravo with 60two stroke.


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