# What to do if motor is too short for transom?



## topnative2 (Feb 22, 2009)

Are u sure u don't have a spun hub? I suggest putting some weight in the stern to get the motor down to see if the problem goes away. And, if it does not u most likely have a spun hub.
Same problem, jack plate would work as long as u can steer the boat.


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## AHerrin (Nov 30, 2015)

topnative2 said:


> Are u sure u don't have a spun hub? I suggest putting some weight in the stern to get the motor down to see if the problem goes away. And, if it does not u most likely have a spun hub.
> Same problem, jack plate would work as long as u can steer the boat.


Sorry for the confusion. The skiff will push on plane. Just not how it should since the motor is somewhat out of the water. The prop spins plenty fine. There's just not enough water in front of it.


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## topnative2 (Feb 22, 2009)

How is the boat sitting in the water when normally loaded?


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## topnative2 (Feb 22, 2009)

There may be an extension pieces available from the manufacturer to lengthen the lower unit.
Jack plate will be cheaper.


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## Vertigo (Jun 3, 2012)

From just looking at your photos, it doesn't appear that the motor is too high. Can you drop it down a few bolt holes? You could also try tilting the motor in to get out of the hole, and then adjusting trim once on plane. A jack plate won't let you lower the motor much before the steering arm will contact the transom, but 4 or 6" of setback may put the prop in better water flow.


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## yobata (Jul 14, 2015)

AHerrin said:


> howdy, I recently put together a skiff and had bought a used tohatsu 30hp tiller to hang off the back of it. Finished the boat and put the motor on last week. When I went to wet test her the prop was cavitating and unable to push on plane. The cavitation plate on the motor is sitting about 2 inches above the bottom of the skiff. I was trying to figure out any ideas that don't involve me shaving off 2+ inches off the transom. Would a jack plate work in this scenario? Any and all help appreciated


What kind of a skiff is that? The motor looks like the cav plate is just above the bottom of the skiff, which is a desirable position for running shallow. Take a straight edge and have it come off the bottom of the skiff and measure the distance between the straightedge and the cavitation plate.


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## Whiskey Angler (Mar 20, 2015)

You could also see about buying a used stainless prop that will fit your motor and having it worked over so it grips. Add cupping, maybe go to 4-blade...

Also, you could consider putting on an after market cav. plate to help collect more water.

There are also some nice aftermarket manual jack plates (much cheaper than a power jack plate) that would allow you to drop the motor. Though, I feel like there is any easy fix for your situation that doesnt require lowering the motor.


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## Whiskey Angler (Mar 20, 2015)

Lastly, lets get some info on the boat, and some pictures so we can gawk


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## Sublime (Oct 9, 2015)

I'm with the others. You should be able to run it like that. My old BT was not a tunnel and the cav plate was well above the bottom of the boat. You have to run the right prop though.


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## jmrodandgun (Sep 20, 2013)

My money is on that little bit of deadrise causing just enough displacement on plane to make the prop cavitate. If it were mine I would shave the transom but small fixed jack plates are cheap and lightweight. A little bit of setback very well may solve the problem.


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## backcast (Apr 9, 2013)




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## backcast (Apr 9, 2013)

I was showing my cav plate above bottom with 4inch setback.
Joe


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## AHerrin (Nov 30, 2015)

Thanks for all the responses. I have a dolphin fin cavitation plate that came with the motor might try that to see if it fixes the problem. As for info on the skiff it's was a unfinished hull from Kingdom boat works


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## devrep (Feb 22, 2009)

doesn't look that high. Assume you have tried trimming down. What is the height of the transom?


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## backcast (Apr 9, 2013)

What pitch is your aluminum prop?


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## WhiteDog70810 (May 6, 2008)

You can get the parts to extend a 15" short shaft to a 20" long shaft. I am not sure how expensive it would be, but I've heard the conversion isn't too difficult.

As mentioned, you can't really lower it because it will likely hit the transom when you tilt it. However, 4" of setback will likely allow you to run it at the current height.

Nate


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## el9surf (Dec 23, 2008)

Cool looking skiff. Is that the one that was for sale here recently? A cupped prop may help as others have suggested.


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## AHerrin (Nov 30, 2015)

backcast said:


> What pitch is your aluminum prop?


I couldn't tell you. It's a stock prop. 


el9surf said:


> Cool looking skiff. Is that the one that was for sale here recently? A cupped prop may help as others have suggested.


I bought it from a guy in charleston 5 months ago. The one I think you're talking about was same hull but built by harry spears and didn't have a molded cap


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## No Bait / Lures Only (Apr 10, 2011)

Cupped prop s/s Power Tec should solve the issue. I have a short shaft motor 15" on a 19" high transom with a 4" jack/setback and it performs good.


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## fatalbert43 (Dec 13, 2006)

It really doesn't look too low In the pictures.

Before you do anything....make a spacer out of wood, starboard, or metal to put between the motor mount bracket and the transom. Make it thick enough to push the motor back as far as the clamps will allow. Then run it and see if it improves. 
After that the next optio. Would be to get your prop heavily cupped or change out to a 4blade prop. 

Seems like a little spacer to shove the motor back and some cupping of the prop would solve your issues.

Then again, the cheapest option would be to cut down the transom a little. But I understand that's a pain and not desired. In reality it's not a horrible job to do and should only take a couple hours work and some cure time.


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## paint it black (Nov 3, 2007)

So we're all just going to ignore that this has HB badges on it? lol


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## Backcountry 16 (Mar 15, 2016)

paint it black said:


> So we're all just going to ignore that this has HB badges on it? lol


Don't let Hal see it.


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## AHerrin (Nov 30, 2015)

Backcountry 16 said:


> Don't let Hal see it.


I told Hal about it when I test drove the Chittum. George wanted to give me his Chittum stickers but it wouldn't piss off the right people


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## AHerrin (Nov 30, 2015)

Tested the motor again yesterday in some calmer water. Put more space between the transom and transom plate as directed and screwed back on the dolphin fin plate. The fin sat right where it needed to be and got me on plane and beyond plenty fine, cruised around 25 and topped out at 33. It was a great 60 seconds until the motor started bogging down and shutting off on me. But I'm not going to deal with that issue myself and take it in to a professional Thursday who'll get me on the water quicker than I can. Once I get the motor in good fashion I'll put up some pictures


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## fatalbert43 (Dec 13, 2006)

Sounds like your set now. It really sounded like a marginal issue.
The motor issue sounds like carbs or a fuel pump. Those aren't too hard if you wanted to try it yourself.


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## DuckNut (Apr 3, 2009)

paint it black said:


> So we're all just going to ignore that this has HB badges on it? lol


I saw that too - you beat me too it. 

However, you forgot to point out the reason his prop is out of the water - HB doesn't float in the water, it rides above it.


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## devrep (Feb 22, 2009)

AHerrin said:


> Tested the motor again yesterday in some calmer water. Put more space between the transom and transom plate as directed and screwed back on the dolphin fin plate. The fin sat right where it needed to be and got me on plane and beyond plenty fine, cruised around 25 and topped out at 33. It was a great 60 seconds until the motor started bogging down and shutting off on me. But I'm not going to deal with that issue myself and take it in to a professional Thursday who'll get me on the water quicker than I can. Once I get the motor in good fashion I'll put up some pictures


Were you getting good flow of water out of the telltale? The Tohatsu's will shut down to idle if they get too hot. A least the newer one's will.


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