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Author Topic:   OUTRAGE 18: Using 20-inch Shaft Motor
JAC posted 11-07-2000 01:07 PM ET (US)   Profile for JAC   Send Email to JAC  
What [would be the consequence] of using an outboard with a 20-inch shaft on an Outrage 18 specified to use outboards with 25-inch shaft? Does the use of a set back or jack plate make any difference?
Lenman64 posted 05-29-2009 11:18 PM ET (US)     Profile for Lenman64  Send Email to Lenman64     
If you use a [20-inch] shaft motor in place of a [25-inch] shaft [motor], the propeller will [ventilate] (grab air) and the engine will over-rev. You will damage the engine. If you put it on a bracket and lower it five-inches the engine will get swamped when you try to plane the boat or stop the boat. Just convert it to a [25-inch] shaft; [it's] not that hard.
jimh posted 05-30-2009 10:36 AM ET (US)     Profile for jimh  Send Email to jimh     
ASIDE: I changed all the references to shaft length to be in inches, not in terms of "short" or "long" as these terms were misused, which is not unusual.

If you really wanted to use the 20-inch shaft motor, you would need to cut a notch in the transom of the OUTRAGE 18. However, do to that would be blasphemy, not to mention tragedy.

If the motor is irreplaceable, find some way to extend its shaft length. Many manufacturers provide kits to do just that. You can sometimes find the parts you need from another motor which has damage to its powerhead, but has its gear case intact.

Tohsgib posted 06-01-2009 11:14 AM ET (US)     Profile for Tohsgib  Send Email to Tohsgib     
If you use a 10-12 inch jackplate setback, you can probably get away with it. I have a 6" setback and my engine is 4" higher, a 10-12 should allow it.
L H G posted 06-01-2009 04:30 PM ET (US)     Profile for L H G    
What Jim mentions is exactly what Whaler did on the classic 19 Outrage, which was before the advent of the 25" engines.
As you can see in the photo, if done correctly, it doesn't look bad. current=Scan0002.jpg .

Peter posted 06-01-2009 06:28 PM ET (US)     Profile for Peter  Send Email to Peter     
Might be a whole lot easier to add a 5 inch extension to motor shaft rather than permanently altering the transom of an Outrage 18. The idea behind the level transom design of the Outrage 18 is to keep the powerhead out of the water if the boat is swamped and having it sit 5 inches lower than the top of the transom tends to defeat the purposeful design.
Kevchap posted 06-02-2009 09:28 AM ET (US)     Profile for Kevchap  Send Email to Kevchap     
I did it with a 150 Johnson 20", it worked great. We re-worked a 6" setback to allow for mounting the setback in the provided transom holes and mounting the engine in the correct spot. I run the engine 2.25" above the keel with a Merc Enertia 19" prop, 49MPH at 5300 is the best I've seen with very little venting in turns and good driveability.

Advantages: lower profile. Disadvantages: took about 2 hours to get everything to fit nice.

I wouldn't do it on purpose but I came by a very nice 150 for free so it was worth the effort.

jimh posted 06-02-2009 09:33 AM ET (US)     Profile for jimh  Send Email to jimh     
With an engine with 20-inch shaft length mounted via a set back bracket on a transom designed for 25-inch shaft length, did you have any problems with the engine getting splashed or washed down by the boat's wake when coming off plane?
Kevchap posted 06-02-2009 04:37 PM ET (US)     Profile for Kevchap  Send Email to Kevchap     
No problems, it works good. It does limit my choices on steering system upgrades because of clearance from the transom. The engine block is 5" lower than a 25" would be. I boat/live on the Mississippi river in Minnesota so I'm not dealing with Great Lakes or ocean type of water. Although some of our cruisers and houseboat wakes come close to replicating that.

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