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Old 23 August 2010, 07:11   #1
jpn
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5.2M need help mounting outboard...

I am mounting a MERC 90HP 2stroke in a 5.2M RIB....right now it is already mounted and I measured the cavitation plate to be 2.5 inches above the bottom of the transom....from what I have read, it should be inline with the bottom of the transom....it's really not too easy for me to do everything all over and lower the engine, but is it really nescessary, or I can just run it 2.5inches above the bottom of transom?
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Old 23 August 2010, 07:27   #2
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You are very likely to get "ventilation" or "aeriation" (not cavitation as some believe !!) which is when the prop is not fully immersed in water.
Does the mounting bracket not have a series of vertical mounting holes which "should" allow you to lower the OB (but probably not by 2.5ins) ?
Probably the best thing is to try the engine as mounted and see how it behaves.
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Old 23 August 2010, 10:32   #3
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For what its worth, the cav plate doesn't neccessarily need to be in the water. The prop on the other hand....

Have a search - plenty of threads about engine height.

I'll second cypman's thought about test it first.
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Old 23 August 2010, 11:46   #4
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Quote:
Originally Posted by jpn View Post
or I can just run it 2.5inches above the bottom of transom?
Try it and see...
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