14x7 cottonmouth cant get boat on plane need help please

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bowfish615
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14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 6:18 am

im new to the airboat community bought this airboat from a friend for bowfishing. im having problems getting up on plane. it will only get up if i get in really shallow water the person who owned before the guy i bought it from said he could get it up in deep water...and i know he did because he fished many 12 hr tourneys. ive read in some research on here that maybe the motors angle coulld be adjusted and also read something about the prop being to far down in the boat....i will post pics later today but i do know it looks as if the rear of motor sits alil low and th eprop when straight up and down is at least 6 inches boat maybe 8...could really use some help thanks..btw the prop is 72 inches 350 dd

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby scottyroll » Mon Jul 14, 2014 7:15 am

What kind of prop? What RPM will it turn at wide open throttle?
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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 3:04 pm

here are some pics...the motor looks like its angled down in rear and prop sits bout 8 inches in boat when in up and down position... prop is 74 inches dont know the pitch fixing to check rpms......but like i said it will get up on plane in really shallow water but i dont have many spots for that locally :rebel:

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 3:05 pm

prop.jpg

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 3:21 pm

it gets up to 2400 rpms....

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 3:24 pm

it also has a single trim plate ...please somebody help me

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby Bruce » Mon Jul 14, 2014 3:24 pm

bowfish615 wrote:it gets up to 2400 rpms....


Thats your problem
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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 3:31 pm

so what does it need to be? and what can i do to get it there?

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby akblackdawg » Mon Jul 14, 2014 3:35 pm

is the guy you bought the boat from close by. what has been changed since you bought the boat. don't change angle or motor mount unless it has been changed already. if it ran ok for the old owner, should be fine now for you if same prop, angle, etc. motor shoud turn up around 3000 rpm, sounds like problem with motor if you are using same prop past owner used. we need a lot more info then "help, boat won't get on plane". Bud
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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby SthrnStyle3 » Mon Jul 14, 2014 3:37 pm

You're gonna need a different prop.. That's too much prop for that direct drive. IMO I would look for a prop anywhere from 68-72" and preferably something adjustable, i.e. a carbon fiber prop.
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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 3:42 pm

the boat ran fine the guy i purchased from could only get on plane in shallow...he bought from another guy we know and they had put the new motor on....the motor sounds great to me it idles awesome no missing....would the motor being angled down and the prop sitting so far in the boat not push it down in the rear?...and what does aboat that size with aprop that big normally idle at?.....im assuming the smaller prop would create less drag on the motor?

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby akblackdawg » Mon Jul 14, 2014 3:56 pm

Where are you located. If florida or other places that have airboat shops and people who specalize in props, you need to see them. Most prop sales people will let you try different props, etc. If motor is strong, sounds like prop may be too big and not allowing enough rpm. if it never did run right, it could be anything or a combination of several things. using jacks on trailer, set trailer so that runners on boat are level, use a bubble level for this. when hull is level, then check level of motor. back of motor should be angled slightly up, so that push from prop will cause nose to lift when running. prop going a few inches below transom should not be a problem. if back of motor is lower then level, it will cause the bow to be pushed down into the water and that would be a big factor that has to be fixed. Bud
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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 4:05 pm

thanks..ill check that...and no im on my own im nashville so no airboat guys here. so motor rear of motor should be angled slightly up? from just looking at it the rear looks to be angled down...ill go put a level on it...thanks

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby scottyroll » Mon Jul 14, 2014 4:10 pm

bowfish615 wrote:thanks..ill check that...and no im on my own im nashville so no airboat guys here. so motor rear of motor should be angled slightly up? from just looking at it the rear looks to be angled down...ill go put a level on it...thanks


You can play with the angle and it may help you at tad bit but I figured you were over propped if you couldn't spin the engine up enough to get on a plane from the get go. The prop has got to be switched out, you will be so much happier with your boat if you do that. Also, check out the classified section on this site and also give some of the propeller manufactures a call, they may have a used prop that is meant for that combo for a good deal.
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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby GeeLeDouche » Mon Jul 14, 2014 4:16 pm

My "WAG" is that you are over propped. Try a prop with less pitch to get you closer to 3000 rpms and I think it would wake that boat right up. a good, inexpensive, ground adjustable prop is a "warpdrive' and they can be had for under 1K in the classified section of the forum. I would probably contact with PTR34 or Plum and see what they recommends also. They both really knows props!
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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 4:31 pm

i checked the level of motor and its lower in the rear about maybe half to 3/4 of an inch

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 4:32 pm

also just found out prop 72/35

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 4:34 pm

thanks ill look into prop...but would adjusting motor help at all in the meantime? its angled down inrear

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 4:42 pm

also would a wooden single blade be good enough...moneys tight...if so what size would be a safe bet?

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby jaxduramax » Mon Jul 14, 2014 5:32 pm

Don't understand all the "over propped" comments before even knowing what size or pitch it was, but then again I'm new here. How's the compression? One post said it had a "new" motor on it. I wouldn't leave it at "seems like it idled good"...

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby fl cracker » Mon Jul 14, 2014 5:45 pm

Great point jaxduramax, I could be a 4 barrel card and the secondary's not opening up? It's either 2 things, to much pitch or motor not performing! I wouldn't worry too much about the motor angle at this point!
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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby bowfish615 » Mon Jul 14, 2014 7:39 pm

will be doing some checks on motor tomorrow

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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby scottyroll » Mon Jul 14, 2014 7:53 pm

Definitely worth looking further into rather than immediately switching props, I agree. Might as well find the sweet spot on the motor angle too once you get it up and running. Every little bit helps. Good luck and Let us know what you find out :salute:
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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby sidejobs » Mon Jul 14, 2014 7:58 pm

It's junk. The end
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Re: 14x7 cottonmouth cant get boat on plane need help please

Postby dblj006 » Mon Jul 14, 2014 8:59 pm

A stock 350 direct drive doesn't have the hp to turn that prop up to 2750. how much do you want to invest? Purchase the prop the engine will turn or build the motor. Search the site about 383's.
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