520 continental

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fanofthesimplelife
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520 continental

Post by fanofthesimplelife » Fri Sep 16, 2016 8:31 am

i have a true aircraft 520 on a 13x8ft hull with ss riggin and a water walker signature series prop 74in my boat has trouble on dry ground i have a sprayer and as long as i dont stop on ground it doesn't do terrible but could definitely be better but how ever if i stop on ground the boat doesn't want to move anywhere! i checked motor angle and it appears to be correct the prop is new and the guy i bought it from said he had someone set it boat pourpouses bad not sure if thats relivent.

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John Fenner
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Re: 520 continental

Post by John Fenner » Fri Sep 16, 2016 9:06 am

What rpm are you turning that prop to @ wot?
I never finish anyth,,,.

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Deano
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Re: 520 continental

Post by Deano » Fri Sep 16, 2016 9:07 am

It is very likely, that is very relevant.

Doesn't sound like there is any reason other than the bottom why your boat shouldn't run dry.
That size hull, with that power, and with that prop should have no problem.

It sounds like the bottom is not flat and/or true. There are multiple ways to check that.
In that regard, the [Search] function at the top right is your friend.

As far as hull tuning goes (motor angle), there is an expanded explanation here:
http://www.southernairboat.com/phpBB3/v ... 85&t=28600
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fanofthesimplelife
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Re: 520 continental

Post by fanofthesimplelife » Fri Sep 16, 2016 11:38 am

turns 2700 at wide open on the water

Dirtman
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Re: 520 continental

Post by Dirtman » Fri Sep 16, 2016 11:55 am

What type of hull (alum. or glass) What type of bottom (poly, slick bottom or just the gel coat)?. And what condition is that bottom in?
IO520 on a 12"6" Lazer with a 72" Q #20814
Build in progress: 14x7'9" JB w/ GSO540 &80" Razor

fanofthesimplelife
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Re: 520 continental

Post by fanofthesimplelife » Fri Sep 16, 2016 12:17 pm

aluminum hull with poly made by alumitech polly appears to be in good condition

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Deano
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Re: 520 continental

Post by Deano » Fri Sep 16, 2016 12:28 pm

I'm not that familiar with the power band of your engine, but if your engine can stand it, that prop may well prefer a few more RPMs. If you set it to get about 2750 on the trailer, you should see around 2900 on open water and might make for some improvement.

Be aware that as long as it's porpoising, it will not run optimally on the water or land.
Your biggest single improvement is most likely to come from remedying that problem.
"The suppression of uncomfortable ideas may be common in religion and politics,
but it is not the path to knowledge; it has no place in the endeavor of science."
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John Fenner
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Re: 520 continental

Post by John Fenner » Fri Sep 16, 2016 12:30 pm

Try getting it to turn 2900 on the water.
I never finish anyth,,,.

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hogdoggin
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Re: 520 continental

Post by hogdoggin » Fri Sep 16, 2016 5:35 pm

Have you checked to see if all your cylinders are warm I'm just thinking maybe you have a cylinder down. Even at 2700 rpm's the boat should still be moving on dry ground. But I agree with the post above I would take some pitch out and turn it 2900 rpm's

blowme
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Re: 520 continental

Post by blowme » Sat Sep 17, 2016 8:24 pm

Bend Down the back with a crescent wrench where the bottom hangs over outside the transom about 6-12in in the center of the boat it works like a trim tab that should help with the porposing if it dosnt pull a string across the bottom u may need a jack ...far as running dry you are asking a lot .. 13x8 aluminum boat needs a carmotor/gearbox on it ... I had a strong 520 on a 12 ft diamondback and wasn't worth a shit on the hill I went back to glass...hell with aluminum boats
what we have here is failure to communicate

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Andrew McD
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Re: 520 continental

Post by Andrew McD » Sat Sep 17, 2016 8:36 pm

Shouldn't have an issue with dry as long as hull is ok, motor is pitched right, and prop is turning right RPM WOT.
If you confident the motor is all good, move to the prop.
Set the prop to 2800-2850 WOT on the trailer.
Even with that, sounds like a lil engine angle and hull tuning would be worth it.
Check the motor for level. Check the hull bottom for anything odd like an indent. May need a little trial and error to get it all where it needs to be.
Remember to do one change at a time so you can see what's working and what's not.
Feel free to pm me your # and I can call you tomorrow or through the week if you want to dig a little deeper.
Water Walker Props, Inc.
(863) 676-PROP

fanofthesimplelife
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Re: 520 continental

Post by fanofthesimplelife » Fri Sep 23, 2016 8:48 am

thanks for all the input this weekend i plan on adjusting the prop and hopefully the extra rpms will help and i have a jack in the center of the boat i have been messing with it to try and get it right took the boat out this past weekend and as long as i dont stop the boat will run dry but as soon as i stop on ground i can get off the boat and mash the pedal and it doesn't move. :florida:

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kwanjangnihm
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Re: 520 continental

Post by kwanjangnihm » Fri Sep 23, 2016 9:06 am

fanofthesimplelife wrote: i checked motor angle and it appears to be correct
where is the motor angle now? is it level with bottom of hull, or is the prop end of the motor angled up or down past level?

have you confirmed the prop is 74"? (hub should be 11 1/4" long) is the tach working correctly?

how is your seat and rigging setup in front of the prop? any air flow obstructions?
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