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Old 18 June 2010, 09:32   #1
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Cobra 7.5M Owners - Compare Speeds

Hi, I recently put a laser 2 prop on my cobra 7.5M running a yamaha 200 2 stroke, while the acceleration and mid range have improved I dont seem to get any higher top end speed, in fact it may have dropped off slighly as I was getting about 44Knots of original prop now im struggling to get 41Knots - sea conditions slight.

What do other cobra owners get from there engine + prop mix and any suggestions as to best type of prop to use.
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Old 04 August 2010, 16:23   #2
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I bought a new prop like the original and have now found my lost knots. I guess with props it's difficult to beat the original spec. Lesson learnt.
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Old 04 August 2010, 19:46   #3
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I have a Verado 200, clean bottomed 7.55 and I get 42 knots max with 2 persons on board.
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Old 03 October 2010, 06:44   #4
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Quote:
Originally Posted by boristhebold View Post
Hi, I recently put a laser 2 prop on my cobra 7.5M running a yamaha 200 2 stroke, while the acceleration and mid range have improved I dont seem to get any higher top end speed, in fact it may have dropped off slighly as I was getting about 44Knots of original prop now im struggling to get 41Knots - sea conditions slight.

What do other cobra owners get from there engine + prop mix and any suggestions as to best type of prop to use.
What revs were you getting?
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Old 03 October 2010, 06:56   #5
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The problem was completely sorted by buying a new prop same as original, it's a yamaha 200 2 stroke, highest recorded speed was 46 knots which is more than enough for me. I'm not going to mess with props again.
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Old 03 October 2010, 07:01   #6
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The problem was completely sorted by buying a new prop same as original, it's a yamaha 200 2 stroke, highest recorded speed was 46 knots which is more than enough for me. I'm not going to mess with props again.
Just wondered as I got 39kn on my 6.65m 200hp yesterday with a Merc offshore series 4 blade prop 22P? I think (Andy B will know, he looked, I'm not going out as it's pi**ing down!)
2 adults and 2 kids, lots of fuel and 5000rpm WOT.
About right?
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Old 03 October 2010, 09:46   #7
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Just wondered as I got 39kn on my 6.65m 200hp yesterday with a Merc offshore series 4 blade prop 22P? I think (Andy B will know, he looked, I'm not going out as it's pi**ing down!)
2 adults and 2 kids, lots of fuel and 5000rpm WOT.
About right?
39kn's on year old fuel with the boats first run in 12months,
far from ideal conditions for a speed run and on a 4 blade prop!
not to bad me thinks!
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Old 03 October 2010, 11:47   #8
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39kn's on year old fuel with the boats first run in 12months,
far from ideal conditions for a speed run and on a 4 blade prop!
not to bad me thinks!
agreed, is it a 22" pitch?
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