Hello, please help

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blueyoda
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Hello, please help

Post by blueyoda » Thu Jun 16, 2016 3:25 pm

Hello everyone, My name is james and I am having a heck of a time trying to figure out what is going on with my little AL boat i Just bought. It's very strange. I have it set up with a 20hp evenrude short shaft. THe transom measures 16 1/2" and the cav plate is 1/2" below the hull. The boat will come up on plane under half throttle and feels VERY squirlly with a lifting sensation on the stern. adding more throttle causes the boat to nose dive HARD and the prop "breaks loose" and motor reves up like mad! If I increase the trim, it won't plane out at all! The boat MAY have been cut down from a long shaft transom to a short as it looks modified. I have never encountered something like this and I have been reading tons of posts. Some say the plate should be in line with the hull, some say up to 2" below the hull? Some say, in shollow conditions run it above the hull? I would really appreciate some thoughts before I start cutting down the hull. edit: it is a relatively flat bottomed boat but not a jon boat.

Thanks in advance for any thoughts given. :help: :doh: :help:



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cape man
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Re: Hello, please help

Post by cape man » Thu Jun 16, 2016 4:03 pm

When you say "increase the trim" do you mean tilting up or down?
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blueyoda
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Re: Hello, please help

Post by blueyoda » Thu Jun 16, 2016 5:04 pm

tilting up. it will only plane out with the trim pin in the first position or removed completly.

BrianC
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Re: Hello, please help

Post by BrianC » Thu Jun 16, 2016 7:42 pm

Is there a concave bend in the keel when you sight along the underside of the boat? It should be relatively straight along the back half to two thirds of its length. I've seen some aluminum skiffs that were bent down like that when someone used a trailer without enough support along the length of the hull. That would certainly explain the diving behavior!
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MrPaul
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Re: Hello, please help

Post by MrPaul » Thu Jun 16, 2016 11:01 pm

I've got an old evin. You say when you go beyond half throttle, "the prop breaks loose". Do you mean the motor pops out of gear and the engine revs like mad? If this is the case, its common on old evins and johnsons. Its either your shift linkage, which is a fairly simple fix, or your clutch dog, which is a bit more difficult. If your motor is popping out of gear, you should buy the repair manual for your model and year and read over the section for linkage and gearbox. You probably already know this but it's nowhere near as complex as an auto transmission. If you think you can fix it...do so. If not get an outboard mechanic to look at it.

Mine was the clutch dog and I was able to fix it with the repair manual. I'm fairly mechanically inclined but by no means a professional.

blueyoda
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Re: Hello, please help

Post by blueyoda » Fri Jun 17, 2016 7:11 am

Brian, I will look for the reverse arch tonight. Rain water does seem to collect in the front of the boat when level on the trailer. Is this correctable or is the boat a right off for larger engines now? will dropping the motor farther down help this?
Paul, not the issue, the prop i still spinning just fine and this boat did the same thing with a friends 30hp. Not a motor issue, it's a boat issue for sure.

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Re: Hello, please help

Post by jacquesmm » Fri Jun 17, 2016 8:54 am

Thanks all for the help but I am going to move this to another section since it has nothing to do with our designs.
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Fred in Wisc
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Re: Hello, please help

Post by Fred in Wisc » Thu Jun 30, 2016 11:08 am

You could stretch a string across the bottom to check for that too.

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