rtbn2fly

I would like to take the time to introduce my self.My name is Rick. I live in Northrn IL been around airplanes 20 yrs just built my 1st boat foam and wood. OS Max .46 Nitro and JR servo's and rx .

I checked balance in the pool and as you can see the first design white foam to narrow added blue core foam for stability has not hit the water yet.

any advise let me have it good or bad.
Thanks RT.

crispyspa

It's hard to tell from the pictures, but is the engine centrally located on the hull? If that's the case, the boat will plow water in the front when you apply power.

rtbn2fly

the motor is positioned almost center maybe a little forward with the radiio gear in the box behind the fuel tank it sets in the water (pool) about level.In the picture the 2 wooden ski,s can be moved forward and back to change the CG.

Thanks for the info RT.

DJLaPalme

With airboats you are not so concerned with c.g. as you are with the balance point. Yes, you want to keep the c.g. as low as you can get it, but the balance point you want 1/3 of the way from the stern to the bow. An example: 36" long hull means balance point at 12" from the back of the hull. As Crispyspa said, your airboat looks like it will plow real bad. It might even go over on its nose. As you run the boat you can fine tune the balance but 1/3 is the best start point on an airboat hull. Good luck and let us know how it goes. Dennis

Selph-Inflicted

Welcome to the airboat side of the rc world!

Got RPM

Welcome Rick! I like your boat design, but like the others have said, the CG is too far forward. The easiest way to change it will be to replace the blue foam sponsons with longer ones - this will help in other ways because the boat is really too short for a .46 and you have minimal flotation. I'd shoot for around 30" to 33" total length, position the new sponsons to get the balance point around the 30% point measured from the sponson transoms. With this modification the boat should work rather well. I'd sheet the sponson bottoms with thin ply to provide a very smooth surface, this will increase speed.

The vertical CG is pretty high, most of us place the radio in the boat hull rather than on the power pod, but it still may work well for you.

For reference, with boats the common use for the term CG (Center of Gravity) means the balance point (or lateral center of gravity) rather than the vertical or transverse centers of gravity.




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rtbn2fly

Well thanks to all the info and advise took every thing in and set it up tonight was the first test run it ran great need to add alot more rudder about a 30 ft arc left or right.
We did take a video as soon as get it downloaded it will be posted for all to see.Ran into bank of lake which has large rocks around bank covered by taller grass damege to left side blue core foam.
List of things still needed: More rudder, and water proof radio gear box; repair dents/dings in left foam. It was starting to bounce or porpoise in the water but that is managed by throttle.
Lots of fun had a great time chasing geese and ducks.

1QwkSport2.5r

I would suggest dumping the air rudders and opt for a wet ruuder instead, if you plan to run on water only with it. Steering is significantly better with a wet rudder.

rtbn2fly

I have thought about that but the lake were we run it is loaded with algae and vegetation that any thing in the water would snag and slow it way down.We have talked about airators on the lake to help but nothing in the works yet.

Did find out that the stering arm that was epoxied into the left rudder split the wood and the hinge point broke.Going to local hobby store to find material that will be corrected and this should not happen again.