Wednesday, August 26, 2015

[Electric Boats] Notes on EV outboard lower unit noise

 

Good Morning
 
Just a note on outboard conversions.  Not all OBs are as equally appropriate to do.  Mine has a noise, a whine as I mentioned before.  Gets louder the faster I go, except in reverse, huh !!  SO --  I just had the lower unit rebuilt, no change that I can tell, on land anyhow.  I had tried thicker lube in the case, nope that just made the rebuild necessary and a bear to remove.  Tomorrow we will try a different prop than the 12 X 12 I have on the boat now, borrowing some may show what's up in water testing.
 
The result at this point is that some ?? makes or models, or sizes – whatever - outboards do NOT make as good a donor lower unit.   We all thought this would be a no brainer, and it is not so !!  An engineer thought the two stroke motors, being louder overall, would be originally designed with way louder gears, since they are not heard in two stroke use.  Probably some or all noise would not be tolerated in the newer four stroke lower gear train.  Others say that is not so, since all the lower ends are helical gears, both forward and reverse, not straight cut at all, and should be quiet.
 
It would help if some others would add some outboard conversion details, or maybe I missed that part somehow.  If I had known about any noise problems for instance, I might have chosen a different donor motor.  The blown 50 Jonnyrude was here, so that's what we used.
 
 
More after we try different props, later ---------  Cal

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Posted by: "cal" <h20dragon@centurytel.net>
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