Hi, this is my first boat build. Not sure what exactly the material i used for the build is called, but i know it's commonly used for building scaled down models of buildings. Planning to throw in a bunch of my aeromodelling stuff into this boat and make it run as an air boat.

Congratuations! You are using Sunboard -what scale, what size? If you are building it to a plan, please point (link it here) it out for us.

Regards.

more pics

thanks for the info.
Not referring to any plans, built it today after a quick look into google images
the boat is 500mm in length.

till this point, a day's build.

GREAT spirit and attitude. Welcome to the forum! Keep us posted.

Thank you

Great show Anjan! It looks really good.

Will follow your post and wait to see it sail

All the best

Hey anjan nice hydro
Dont you think a hydro is a bit too much for a first boat
And it being a hydro i think you will need quite a bit of reinforcements on it if you plan to go race class.
May i ask what is your power system and AUW?
Awesome build man

thanks a lot, Sanjay! might take a couple of weeks beofore i can make time to finish it and do the testing, hopefully it's all waterproof.

Thanks man
the hull is 70% completed and weighs about 190g currently. expecting it to be around 250g fully finished without electronics.
w/all electronics expecting it to be around 400-450g
i have a bunch of aeromodeling stuff, going to run it on a 1400kv motor with a 7'' or 8'' prop as an airboat.

Post a video when you are done. I love airboats!! Is this your first airboat? If so, then you should make sure that:
1) Your CG is as low as possible. Otherwise it will go upside down quite easily
2) Keep the C.G. at about 30% of the total length forward from the transom,i.e., if your boat is 100cm your cg should be within 30cm measured from the back.

yes, this is my first air boat. thanks for the info, appreciate it.
the 30% CG point is to keep the nose from lifting off?

You can say that.. The way you mount the motor is crucial. That determines the perfect cg point for your boat. Since you are building your first one, I suggest you make provisions for a adjustable motor mount. If its a pusher your motor needs to point up a bit. Point a bit down for a puller. You need to play around with the angles to get the perfect balance between speed and stability. Try and keep the propeller at the C.G.
AND post a video when you are done

sure, but right now the back end seems to be a bit heavier than front, even with all electronics put as far front as possible.
what  if i have a more-than-30% cg and increase the angle on the prop, will that compensate the rear end weight?

i'm planning to go for the pusher setup as i'm using a prop adapter that could be dodgy, so dont want the prop to fly away in a puller

also, is it okay if i use in-water rudder? i could build a rudder behind the prop though.

Build almost done. Have to make extension for motor wire and check for leaks in the hull for one last time tomorrow before some paint and decals go on

...

...

Very interesting motor mount and position. I had expected a cockpit in the front and a normal prop in the rear or mounted on an extended boom in the front. Hadn't expected a pusher. Will be waiting to see her sail.

i could conveniently house everything inside the hull and I'm not that much into scaled details, only functional, so no cockpit.

pusher setup because i've always felt a bit insecure about those prop adapters, i dont want it to loosen up and the prop fly away; in pusher, the prop would be pushing against the motor so, slightly safer i think.

motor mounted up front because CG was at close to half the length, so had to put some weight up front. even the pins are made of depron to save weight

will be testing it this weekend hopefully.

All the best. Ensure that you videograph her maiden for all of us to learn. I had started building a similar boat but then an over enthusiastic visitor stepped on my hollow Depron sponsons and destroyed her. Haven't had the heart to throw her away. Hope to rebuild her someday,

i know about those ''over enthusiastic'' people, they usually ruin my servos while trying to move them by hand

i'm going to meet Akash, a fellow boad builder i met on here, just hoping everything to go well, if not great.

my boat's AUW is close to 800 grams now, is that too much? the motor produces 1010grams of thrust in my setup. 

800 gms versus 1010 gms sounds pretty good for a first air boat, IMHO. Let the experts comment and guide.

Your motor position is interesting I have seen front mounted pullers, the fastest airboats use that setup. Just do one thing. After you have installed everything, pick up the boat by putting a finger under the motor shaft between the prop and the motor bell. The rear of the boat should hang lower. Start off with zero thrust angles. Run the boat. If you see that the nose dives on throttling up, move the CG back and try again. Best of luck

Your CG SHOULD be behind the half way of the hull. I never had to put any weight up front..

i'm starting to think this motor mount was a bad idea
i'm just gonna put all electronics at the rear and see what happens.

Guys, the boat's done. Named it Satanic--like titanic 
Going to maiden it tomorrow at the lake, if it doesn't rain much out here in Bangalore

...

couldn't run it much, i was holding the camera in one hand and transmitter in the other. waiting to test it at the lake 

To the lake now!

First thing tomorrow

Congrats and all the best!

Hi Anajan,
If you add a elevator their (don't know whether it is correct norm for air boats) will it effect the characteristic of sailing. I mean a better balance can be achieved without much changing the angle of motor mount.

Thanks

it should. and i'm already looking into building a proper 3 point hydro in a few weeks.

Any updates ?

Tested the boat at the lake today, a pond actually, too much wind and waves to try it in the lake.
Hadn't expected my first boat to be so awesome 
One of the gate police at the lake broke a rudder while trying to move it but managed to slightly fix it up and it was ready for it's maiden 
Few small damages , but fixable.
hope the video is good enough. any suggestions to make the boat sail better are welcomed.

Appears like the boat is ready to take off ... Nice work

Great 

Need a bigger lake

Awesome speed

yeah, need to shift CG slightly forward

This is a small pond at the lake, it was too windy and too much waves to test in the lake, so tried it in the pond.

i guess, i didnt go beyond 1/3 throttle as it was a small pond. just waiting for the winds to calm down

Instead of shifting the CG forward, angle up the motor a bit by putting washers on the bottom mounting-screws. I use the little black rings that come with the propellers (shaft adapters).

I tried that, but the motor angle required to keep the boat from flipping out is getting it to nose dives into water at slow speeds. At 1/3 throttle it's all fine, but at 1/2 throttle or less, nose will be at water level.
also, no washers required, made an adjustable angle mount

Don't muck around with the motor angle now - you will destroy the build. Go to a wheel balancing shop and pick up loose lead weights (they give them away for free). Put some weights on the fore part of the model and ENJOY! This baby has  some great speed. I only wish that you had made her with a scale cockpit and had painted/detailed her to resemble the actual thing.

This looks like a schematic scientific test model rather than a RC Scale boat model.

Sorry if I am being blunt - but then that is just me...............I've always been partial to scale and detailing

Very well done  

VC, i'm planning to build a proper 1/10th scale hydroplane, will take care of the detailing in that, this is only my first boat

I will try moving the battery towards the nose and if it still doesn;t handle right, i'm gonna go with your lead weight suggestion. just that i dont want dead weights onboard.

Got rid of the less-effective air rudders and added a water rudder. Handles beautifully, very agile.

Might as well make a regular boat then. An air boat should be able to skim over solid smooth surfaces too