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Transom height?


GregH's Avatar
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09-01-02, 10:36 AM   #1  
Transom height?

On a 16' Tracker, I raised the short shaft transom from 15" to 20 " which I thought was the correct height for a long shaft motor.
The anti-cavitation plate on my '88, 30 hp long shaft Johnson sits about 1 1/2" below the hull.
Should the plate be even with the bottom of the hull for maximum efficiency?


GregH.........HVAC/R Tech

 
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BoatMech's Avatar
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09-01-02, 10:10 PM   #2  
What kind of boat, pontoon or bass.
Ideally the ventiation plate should be just about 1 ''
below the bottom of the boat. But with sixteen feet and 30 hp.
I wouldnt worry too much.
Sounds like you got it right.

 
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09-02-02, 07:39 PM   #3  
telco tech
At 30 HP, the motor height will not be to critical. As long as the motor does not cavitate after the boat planes out or when you turn, you should be in good shape. I have a little 14' with a 40 HP and I added a fin to the outboard, it helped it plane out faster, and made it more stable in turns. ( it felt a little squirley before).

 
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09-04-02, 05:52 PM   #4  
Thanks for your input.
It does run fairly well even for being underpowered.
During one slow winter I made-over the plain fishing boat with an 11 gallon built-in gas tank, livewell with fill and empty pumps, running and interior lights. rod locker, casting deck with underneath storage,GPS and depth finder, bilge pump, swivel seats, three storage compartments and a solid floor. I also run a 9.9 hp Johnson back up motor.
Even though it is rated for a 40 hp my 30 will plane and run at between 20 and 25 mph.
I am getting a fan shaped rooster tail close to the motor from the fin I added and am unsure of what causes this.


GregH.........HVAC/R Tech

 
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