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Boat wobbles alot

Old 08-08-2008, 09:14 PM
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ddorche
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Default Boat wobbles alot

Hey guys ,

Have another newbie question .

I went on the water to try the boat with new engine in and the hull was pretty wobbly at higher speeds. sort of scary to control.
Is this more user lack of running experience or i can do some tweaking to the hull? Or both. I'm new in rc boats, so there is definitely alot to learn.
The boat is the AQ V24 with Sikk 27 and 275 prop.And it seams to run quiet wet.
Any suggestions? i want to take it back on the water tomorrow so please fill free to shoot anything that could help.

Thank you
Dan
Old 08-08-2008, 09:25 PM
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schnipster
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Default RE: Boat wobbles alot

a friend of mine has one....2 things
first =make sure your drive sytem is straight out from the back not trimmed up, this makes that boat run unstable
second=the adjustable trim tabs need to be straight out if not about 2 mm down from straight out inline with the hulls running surface

both of these items will push the nose down a little and i seems to work...not a pro just seen what my buddy did
Old 08-08-2008, 09:58 PM
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ddorche
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Default RE: Boat wobbles alot

that make sense , thanks for the tip mr. will try that .
Old 08-09-2008, 01:28 AM
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Doubledog
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Default RE: Boat wobbles alot

adjust the tabs a tad at a time.
Old 08-09-2008, 10:43 PM
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ddorche
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Default RE: Boat wobbles alot

Thanks for the tips

burned 3 tanks, on and off, playing with different setups, trail and error. Nothing helped to unload the extra "wet ride" that engine had to push.
But tips regarding the prop setup, trims helped to keep it more solid on water.
I never had a chance to see how fast it could go: The hull was pulling hard to RIGHT at around 3/4 of throttle.Beefy servo? should i move the rudder farther pass the prop line?
I tried two of my only props and both were pushing the hull 100% better with this engine than fuji.

Any more tips on the ruder setup or any comments i would really appreciate!

Thank you
Dan

Im little scare to run this thing , the way it leans, and the fact it not planing so well .... i guess its the design thing
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Old 08-09-2008, 11:01 PM
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coyv10
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Default RE: Boat wobbles alot

Any idea what prop you are running? because sometimes a prop that is too large will cause this and some 3 blades will do this also (pull).
Old 08-10-2008, 12:33 AM
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ddorche
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Default RE: Boat wobbles alot

Coyv,

I was running Prather 275 and the stock prop that came with the boat . Both props balanced.
The stock prop was not as bad in the higher throtle/speed range as the 275 prop. I could not get as much speed out of stock one.
both props are 2 blade.

sorry for bugging everyone on every single forum i know , its just learning experience and anyone's help is priceless for me .

thank you
Old 08-10-2008, 12:39 AM
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Default RE: Boat wobbles alot

[:@] , indeed WAAaaayyy too wet, recheck your CenterOfGravity,and/or raise the back of the stinger....... [8D]
Old 08-10-2008, 01:28 AM
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ddorche
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Default RE: Boat wobbles alot

the cg is around 31%,
we played with all the possible options and i run out of ideas. Seams like this type design likes to run wet , based on the way the surface was designed.Anyone here running this hull with good luck at higher speeds?

Old 08-10-2008, 12:43 PM
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Default RE: Boat wobbles alot

lets see some pics of the stinger. i used to run mine with the stinger angled up just a bit. im a newb also so i could give you aproximate angle, but it doesnt take much. i just moved it a bit at a time till i got it runnin to the point that i was happy. the fastest my boat went was 36 with the stock fuji[&o] shes long gone now, sold to friend.
Raymond
Old 08-10-2008, 01:02 PM
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Default RE: Boat wobbles alot

ORIGINAL: ddorche

the cg is around 31%,
we played with all the possible options and i run out of ideas. Seams like this type design likes to run wet , based on the way the surface was designed.Anyone here running this hull with good luck at higher speeds?

there is NO set formula as to where your COG should be,it can range anywhere from 27% - 35%,when someone references it should be 30%-33%,this is only an approximation,and could be significantly different than that depending on engine,torque,hp...etc..... return all adj. you made to neutral,and start adding weight to the back of the boat,this can be done with a small bottled water,if too much weight,empty some water out,until you find the sweet spot,and the hull rides "right"...you can then weigh the bottled water and switch to stick-on lead weights,or,you can relocate your engine to compensate..... [8D] all the adj.you made to stinger/tabs should be only 2-4mm,anything more than that tells you something else is outta whack... [:-]
Old 08-10-2008, 09:08 PM
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monsterbrad
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Default RE: Boat wobbles alot

I would try trim tabs and turn fins on that boat the pics explain it all.
Good luck
Old 08-29-2008, 11:27 AM
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ddorche
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Default RE: Boat wobbles alot

little update on the boat makeover.
we mess with the hull for past 4 weeks trying to get it to run "better" and peaty much we run out the options.with the cg at 27% it was the best run... we got out of the hull 36mps, where the goal was 40.I think 30plus on this type of hull design is not bad . It runs better in the rough water than in nice and calm. I guess it could benefit from different drive setup, where the prop sits below the stern...Its heavy and handful. Hey but it was fun and nice learning experience. Thanks everyone for help. here is the crazy boat on the pond last week:
http://www.youtube.com/watch?v=iLi9O9xbL_o

Thanks
Dan
Old 08-29-2008, 12:05 PM
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Default RE: Boat wobbles alot

Hey Dan,thanks for the vid.,it really sez it all,and will help in the eval and suggestions that will soon be presented to you by others.....the ride kinda reminds me of a B-52 in flight....what kinda prop are you usin, if it's a 3/blade...lose it...too much lift...another thing to check for is if your hull has "hooks" in it...Hooks are concave depressions/imperfections in the hull which create a suction,sucking the hull down into the water....you can check for this by laying a straight edge along and in-between the strakes and chine(lengthwise)along the keel,and to the transom, and shine a light from the other side,if you notice dips/light shining thru at any points,then that is your problem,and requires a major fix.....(new hull)... [] ,for no matter what you try to do to trim it,the stability will not be there,...if your hull is straight.... , then what the heck...reset your COG to v24%.... lol.... and/or raise the back of your strut/stinger for a more positive angle of attack...... good luck....let us know if the hull is straight.... [8D]
Old 08-29-2008, 12:18 PM
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Default RE: Boat wobbles alot


ORIGINAL: schnipster

a friend of mine has one....2 things
first =make sure your drive sytem is straight out from the back not trimmed up, this makes that boat run unstable
second=the adjustable trim tabs need to be straight out if not about 2 mm down from straight out inline with the hulls running surface

both of these items will push the nose down a little and i seems to work...not a pro just seen what my buddy did
if your boat is runing wet,(and it is!)then you need to do the OPPOSITE of what is quoted above,as this info will do nuthin but force your bow down even further.... post some pics of your set-up inside and out,including the transom hardware w/different angles.... [8D]
Old 08-29-2008, 12:25 PM
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Default RE: Boat wobbles alot

Way too much lift on that prop by the looks of it,the boats ploughing as the transom lifts ,i also think that your balance is way off too.Show a pic of your prop angle my betting is you have way too much negative in it pushing the bow down hard.
Mart
Old 08-29-2008, 01:15 PM
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ddorche
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Default RE: Boat wobbles alot

Hey guys,
Yo know we tried every possible prop angle , quiet a few props including the props with shaved lift 2 and 3 blades(was running it with local club guys ,lots of props to test). The running surface was redone , straight like it should , sanded with 600. We even added some water ballast on the last few runs. Boat its kinda heavy , stepped design , and seams like surface drive does not suit it the best? Guys from MHZ have their hull DPX24 running with Z Drive , and based on their info this was the only way they could get it flying. Honestly this thing kinda burned me out , past 4 weeks i was working on this hull incorporating suggestions from the posts and friends... I think i might give it little brake and get my other hull running. .. haha just like little brake from the kids.
Old 08-29-2008, 01:22 PM
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Default RE: Boat wobbles alot

WAY WAYYYY TOO MUCH NEG

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