i/o vs OB performance or just stupid

[snoman]

:redface:I guess I am leaving myself open but I am looking for some info. I had a 16' OB (90hp)that I just traded for a 2002 Stingray 18' i/o (135hp). When I took it out yesterday for a test run, it turned on a dime but I think I could have flipped it! I could turn the 16' at full speed no problem. Now I am concerned about letting my teenagers in it. Is this because of more power, i/o or both? Also, it seemed pretty high on RPM's (4+) is this normal?

 

[QC]

Re: i/o vs OB performance or just stupid

They'll only do it once . . .

 

[tashasdaddy]

Re: i/o vs OB performance or just stupid

it is the difference in hull style. every boat handles differently. i would expect to see atleast 4 grand. your outboard was suppose to turn, 5500+

 

[Gary H NC]

Re: i/o vs OB performance or just stupid

The I/O has a lower center of gravity and will handle much different than an outboard.If it feels like its going to flip it probably will.Whats the need for high speed hard turns?

 

[Silvertip]

Re: i/o vs OB performance or just stupid

4400 - 4800 is the recommended WOT RPM range. Prop selection for an average load determines that.

 

[JCF350]

Re: i/o vs OB performance or just stupid

Your teenagers safety is going to be up to you, as always. Teach'em right, point things like this out. You can learn the differences yourself first then pass it along or learn together.

 

[ovrrdrive]

Re: i/o vs OB performance or just stupid

Wide open turning in any boat is something that should be done with care. I say buy the boat you want, put them through every safe boating course you can find, and supervise them driving it until you are comfortable with their skill levels.

The first boat I ever ran was Dad's old 16' speedboat with the Merc 135 on it. At 55+ mph it would start to chime walk and if you hit the waves wrong it could possibly flip over going in a straight line.

I never came close to turning it over...

 

[180shabah]

Re: i/o vs OB performance or just stupid

Is there a hydrofoil on that stingray?

What you describe is exactly why mine came off.

 

[snoman]

Re: i/o vs OB performance or just stupid

great forum! It sounds like there is a combination of reasons, hull type, center of gravity & hydrofoil. I certainly won't try that again.
I wish I knew the issue with the high RPM's (I do not know what WOT is) it could be that is was very cold that day. But I did warm up for an unusually long time compared to my fuel injected Suzuki.

 

[oops!]

Re: i/o vs OB performance or just stupid

cold shouldnt matter at wot, mabe just a tad higher. (50 -100 rpms)

check to see if you are proped right, as 4 is low, (could be used for skiing)

still wont help with teens partying......

 

[180shabah]

Re: i/o vs OB performance or just stupid

great forum! It sounds like there is a combination of reasons, hull type, center of gravity & hydrofoil. I certainly won't try that again.
I wish I knew the issue with the high RPM's (I do not know what WOT is) it could be that is was very cold that day. But I did warm up for an unusually long time compared to my fuel injected Suzuki.

-Your are correct, this IS a great forum.

-We still haven't established, What do you mean by "the issue with high RPM"???? Was that the minimun RPM that you could hold plane, was it the max RPM you could achieve?

-Carburated engines are more sensitive to temp than a fuel injected engine. A longer warm up period is normal.

 

[Gary H NC]

Re: i/o vs OB performance or just stupid

WOT is wide open throttle. With it trimmed out for maximum performance it should be 4600 to 4800 RPM. If not a prop change may be needed.You also need to consider the average weight you will carry,fuel,gear,people,ect..
If the engine is turning 4800 RPM with one or two people onboard then you will drop to 4500 or so with a full load.