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Twin BF40's Prop Wash / Exhaust Not Same

glaspro19

New member
I have twin bf40's both exactly identical, same props everything.

Question is... Why is it that when I run it on the lower rpms 1200-1500 one engine has very noticeable prop wash/exhaust (the white tube made by the props) and one doesn't ? are they not running at the same speeds?

Do I need to sync my tachs?
 
Here is a guess. My thoughts are that since the 40's are both right handed props, that the wash from one of the props is affecting the wash of the other one. Let me guess...the port engine is the one that makes the white tube...just a guess.

In any case, I would not expect the prop wash to be symmetrical, since the port motor is not counter rotating.

I am sure Professor Jimmy D will have some thoughts....

Mike
 
Yeah, I was thinking...What is Mike gonna say about this one?

I know it will sound crass but I was thinkin' the same thing. The only words of wisdom I could offer would be to try an experiment.

If you have a GPS or a reliable speedo, power the boat with one and then the other outboard by themselves. This may require that you uncouple the throttle if it is rigged for one control.

If one outboard outperforms the other, then you have some troubleshooting to do. If they both power the boat about the same, then I believe Mike's answer is proven and you have nothing to worry about.
 
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