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25" outboard on 20" transom? - Walleye Message Central
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Old 10-08-2021, 08:09 PM
Steven Pederson Steven Pederson is offline
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Default 25" outboard on 20" transom?

Good evening fellas,
I'm currently building a Crestliner Commander replica. Boat i'm building up is a 1992 Crestliner Phantom 186. I'm looking to repower the 115 mariner to a EFI 115-140HP 4stroke.

the issue i'm having is most of the outboards i see for sale are 25" outboards. I know there are different holes to mount. Any one have any success mounting on a lower hole to raise the motor? Strictly thinking outloud i would almost prefer a 25" as it would raise the motor out of the water higher for back trolling in larger rollers.

thoughts? 25" doable or should i continue my 20" search?
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  #2  
Old 10-08-2021, 08:11 PM
S.Larson S.Larson is online now
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Mounted high on a jackplate and it should be fine,....
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Old 10-08-2021, 08:13 PM
Hot Runr Guy Hot Runr Guy is offline
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Steve, maybe use something like this?

https://thmarinesupplies.com/collect...ical-extension

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Old 10-08-2021, 08:15 PM
Steven Pederson Steven Pederson is offline
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Quote:
Originally Posted by Hot Runr Guy View Post
Steve, maybe use something like this?

https://thmarinesupplies.com/collect...ical-extension

HRG
Awesome, thanks. I'll look into these.
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  #5  
Old 10-09-2021, 12:14 AM
Snowking Snowking is offline
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Are you looking for a used fourstroke or new. If new I would just order a 20 inch. Why have the motor mounted so high in the back with a 25 inch motor on a 20 inch transom. If looking for used. I think I would expand my search down south. As allot more low profile boats sold farther south. Maybe more used 20 inch motors around.
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Old 10-09-2021, 03:59 AM
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last chance last chance is offline
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you would need a jack plate with at least a 5" lift to get it high enough for optimum performance or travel a ways if you have to to get a 20" to start with. if you go the jack plate try to find one with a 5" lift or more if you can find one. but most jack plates only has 4" of lift. but you could get a 4" the mount the motor in a lower hole.
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Old 10-09-2021, 02:06 PM
REW REW is offline
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Steven,
If you are rebuilding the boat, just take the time to remove the transom board, and install a new board with new appropriate material and application, with s straight top in it with no motor cutouts


That way, you take advantage of the longer motor leg, by creating a taller finished transom in your boat.
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Old 10-10-2021, 05:36 AM
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doubleheader doubleheader is offline
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Steve,
I really donít know how much success youíll have trying to find a 4 stroke specifically for a 20Ē transom, and while I donít know your location perhaps a call to Blackbird Industries Inc, in West Sunbury PA can help sort this out. They are the outfit that repowered my friendís refurbished Sylvan in my recent post. Google them, quite an operation. Remember, the main reason boat manufacturers went to a 25Ē transom was the weight of the first generation of 4 strokes, so youíll have that weight to consider. I would not rebuild the transom if itís solid, but what I might run by Blackbird would be splitting the difference in mounting holes.


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Old 10-10-2021, 08:31 PM
Steven Pederson Steven Pederson is offline
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Quote:
Originally Posted by doubleheader View Post
Steve,
I really donít know how much success youíll have trying to find a 4 stroke specifically for a 20Ē transom, and while I donít know your location perhaps a call to Blackbird Industries Inc, in West Sunbury PA can help sort this out. They are the outfit that repowered my friendís refurbished Sylvan in my recent post. Google them, quite an operation. Remember, the main reason boat manufacturers went to a 25Ē transom was the weight of the first generation of 4 strokes, so youíll have that weight to consider. I would not rebuild the transom if itís solid, but what I might run by Blackbird would be splitting the difference in mounting holes.


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thanks. the only motors i'm seeing that are 20" are off pontoons. There is a local guy here who says mounting a 25 on a 20 is no problem and he does it all the time. I might go over and talk to him in person, maybe he's got a boat on his lot he can show me.

this is a Crestliner with the SST transom, it's got that stupid cut out to lower the outboard. Everything is welded so i really don't want to start tearing into it. i was looking at my current set up and it looks to be about 4" of play in how that motor could be mounted. the research and search for a motor continues!!!
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Old 10-10-2021, 10:10 PM
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I had 25" Yamaha f150 4 stroke mounted on a 20" transom 1987 Lund Baron and it worked fine, so yes it can be done. But i would look at some bass fishing websites as those boats are all 20" transoms so you could probably find a motor there. I would try to find a 20 before going the 25 and jackplate route.
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