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Center of Gravity (tunnel hull)

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Old 11-04-2004, 12:22 PM
  #1
wiz0852
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Default Center of Gravity (tunnel hull)

How about a little discussion on CG??? do you figure it with engine on, full or empty fuel tanks, how many different ways are there of doing it... just a general discussion... Gary
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Old 11-04-2004, 11:49 PM
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Default RE: Center of Gravity (tunnel hull)

Gary, empty tank, all gear including radio and motor with the CG at right around 27% forward of the transom. You can then adjust from there for conditions. You can use stick-on weights if you need to for balancing it out. Some tunnel hull boats have the fuel tank mounted over or near the CG which helps to keep it from moving as the tank empties.
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Old 04-22-2006, 09:24 PM
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Default RE: Center of Gravity (tunnel hull)

Good Nigth, I have a TS2 with OS21 OB engine (stock) and i cant find a aceptable setup, because the manual recomend tha the CG is 9 1/2 inch from the back of sponsons and the weight in nose section should be a 1 to 1 1/2 Oz, at this point i dont have a CG, i should put 4OZ in the nose and then find it.

Otherwise the % is around 33% from back to the bow. Hwho can help me with this setup? Thanks guys

excuse my bad english.
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Old 04-22-2006, 09:45 PM
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Default RE: Center of Gravity (tunnel hull)

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ORIGINAL: Cristian Aldana

Good Nigth, I have a TS2 with OS21 OB engine (stock) and i cant find a aceptable setup, because the manual recomend tha the CG is 9 1/2 inch from the back of sponsons and the weight in nose section should be a 1 to 1 1/2 Oz, at this point i dont have a CG, i should put 4OZ in the nose and then find it.

Otherwise the % is around 33% from back to the bow. Hwho can help me with this setup? Thanks guys

excuse my bad english.
Cristian, welcome to RCU. Don't worry about your English, it's better than many I see here who are from the US! I run my TS2 with 4.5 ounces of weight in the nose. I started with 4 ounces inside the front of the cowl and ran it a bit. It seemed a bit light in the nose so I added the extra .5 ounce. I use standard servos, a Prather 215 prop, and the engine is set according to the directions. I have yet to measure the CG, I just run it. So far, I'm happy with the way it runs.
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Old 04-22-2006, 10:46 PM
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Default RE: Center of Gravity (tunnel hull)

Thanks you Piper Chucks, only two question more, always TS2 have a tendecy of spin in the turns like see in manufacter video, or with that weigth in the nose 4.5oz also correct the problem. I say it because i have a old tunell hull dumas i believe and it was great hull in turns with the same engine.Thanks guys.
[img]C:\Documents and Settings\Cristian Aldana\Mis documentos\Mis imágenes\CANON1\canon1 038[/img]




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Old 04-23-2006, 08:19 AM
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Default RE: Center of Gravity (tunnel hull)

Tunnels are capable of turning very sharp, sometimes when you don't want them to. Avoiding spins is a combination of proper setup, and driving. I won't claim to be the most knowledgable about this, but what works best for me is to reduce the throttle a little just before I begin the turn. This drops the bow and lets the inside sponson bite into the water. Then gradually apply throttle as you are making your way through the turn. The times I'm most likely to encounter a spin is when I try to maintain full throttle all the way around the course. What appears to happen is that too little of the inside sponson is in contact with the water, but then it suddenly drops down and the boat spins out. When I'm running my monos or hydros, I can maintain full throttle all the way around the course, but the tunnels require more throttle management.
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Old 04-23-2006, 09:06 PM
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Default RE: Center of Gravity (tunnel hull)

Today test the TS2 with 4 and 4.5oz in the nose and run very well, the all setups i like with 4Oz and neutral trust, work great, but next weekend i will try to make a bit positive angle to see what happen , thanks Mr. Chuck

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Old 05-11-2006, 02:25 AM
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Default RE: Center of Gravity (tunnel hull)


Quote:
ORIGINAL: Ron Olson

Gary, empty tank, all gear including radio and motor with the CG at right around 27% forward of the transom.
Ron, CG is always checked from the back of the spoons, not the transom. Some transoms are inserted, which would throw off the CG.

Every tunnel is different. CG is anywhere from 27% - 33%.. My TS2 has 2.5 oz of lead soup in the cowl nose with 2 oz under the cowl in the slot. Boat has had only a handful of runs before the motor started to give out. Those runs didn't have any ill effect from handleing.
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Old 09-29-2017, 05:51 AM
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Default Nito tunnel hulls

Guys do you measure cg from the back of the sponsons....and if so what %
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Old 09-29-2017, 07:59 PM
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Quote:
Originally Posted by Nitro boater View Post
Guys do you measure cg from the back of the sponsons....and if so what %
OB Nut answered your questions in the previous post. He called the sponsons "spoons" but the effect is the same
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