Problem with Balancing of my boat.

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7 May 2011 at 08:50 #6706
Muhammad Awais
Participant
@muhammadawais53838
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7 May 2011 at 08:50 #30519
Muhammad Awais
Participant
@muhammadawais53838
i’ve made an RC boat from scratch. When i put it into water, it is not stable, it tilts towards sides. Plz tell me what should i do
7 May 2011 at 09:40 #30521
Bob Abell 2
Participant
@bobabell2
Hello Muhammad

We need to know what type and size of boat you are talking about and if possible, a photograph

Bob
7 May 2011 at 17:03 #30529
Muhammad Awais
Participant
@muhammadawais53838
how can i insert an image from my computer here?
7 May 2011 at 17:07 #30530
Muhammad Awais
Participant
@muhammadawais53838
this is the photo of the boat.
7 May 2011 at 17:14 #30532
Bob Abell 2
Participant
@bobabell2
Hello Muhammad

Your picture has appeared OK

Your model looks rather tall and top heavy!…….Is this your own design?

You need to position the battery as low as possible.

I would suggest adding extra width at each side like outriggers etc

Bob
7 May 2011 at 17:19 #30533
Muhammad Awais
Participant
@muhammadawais53838
hello sir,

yes this is the design and i have figured it out that even after putting the battery in the bottom didn’t work…. The center of gravity is way to high than expected :-@

i need another weight i think.. thoughts??
7 May 2011 at 17:49 #30534
Bob Abell 2
Participant
@bobabell2
You can try more ballast, but the hull looks a bit too narrow

I suggest you add extra width in the form of sponsons, similar to this model…

I had the very same problem!

Bob
8 May 2011 at 07:55 #30541
Muhammad Awais
Participant
@muhammadawais53838
i suspect extra width added would increase the drag force and hence reduce the boat speed. I’ve found the solution by adding s small chamber at the bottom and putting some lead in it. Now the boat is really stable. ‘ll upload pics soon.

Thanks BOB
8 May 2011 at 19:34 #30545
ashley needham
Participant
@ashleyneedham69188
Hmm…is this an airboat?? judging by the propeller.

If it is an airboat you will need to widen the hull until it is stable, as adding lead, although this WILL stop it wobbling, will also kill the speed..which is what airboats are all about.

secondly, do we assume its not finished yet? and , what is the superstructure made from please.

Ashley oh, and some measurements would be interesting and your propulsion details.
8 May 2011 at 19:45 #30547
Muhammad Awais
Participant
@muhammadawais53838
Posted by ashley needham on 08/05/2011 19:34:52:

Hmm…is this an airboat?? judging by the propeller.

If it is an airboat you will need to widen the hull until it is stable, as adding lead, although this WILL stop it wobbling, will also kill the speed..which is what airboats are all about.

secondly, do we assume its not finished yet? and , what is the superstructure made from please.

Ashley oh, and some measurements would be interesting and your propulsion details.

Yeah its an air boat and its not finished yet bcoz of the unbalancing problem occurred unexpectedly. The material used is cheap Ply Wood available in local market and design iz my own.

Motor is Tower Pro 18T with 6×5 propeller [ propeller size limited due to hull :'( ]

need some suggestions about coloring scheme coz i’m very bad at having ideas 😀

Awais
8 May 2011 at 19:49 #30548
Muhammad Awais
Participant
@muhammadawais53838
i don’t think there would be a considerable effect on the speed due to lead bcoz there iz not much difference noted in the contact area with water but the change in position of CG
9 May 2011 at 15:40 #30558
ashley needham
Participant
@ashleyneedham69188
Its not so much the contact area, but the weight that is the problem. For an airboat, you want as little weight as possible in order to get the performance. This is why extending the sides out would be a bit better idea, for more stability rather than adding weight. Adding weight is not a problem on a Tug for instance, but is so on anything fast…speedboat etc.

The superstructure needs to be kept to a minimum, so unless you have a design i would suggest removing or lowering that which is fitted..OR making it out of something lighter, balsa wood or polystyrene (tiles, can be used)..or even ordinary card..this would be ok provided it is painted all over.

Traditionally an airboat has a badly modelled driver sitting on a chair as the only superstructure..cant go wrong with that. Colour…anything you have handy, or how abouit a green/brown or green/black camouflage finish. or a similar scheme but using whatever paint you have.

Ashley
11 May 2011 at 06:22 #30580
Muhammad Awais
Participant
@muhammadawais53838
yes you’re right, the added weights had a considerable effect on the boat speed, it marely gets 5km/hr now :'( .

here are some images of boat after painting

now i am planning to change the hull size badly but it’l require a lot more effort
11 May 2011 at 09:44 #30581
Colin Bishop
Moderator
@colinbishop34627
Looking at the photos, the boat simply seems to be too tall and narrow to be stable. Airboats are usualy around twice that wdth proportionately. As you have found, adding weight significantly reduces performance. Lightweight outriggers as previously suggested would be better although they would slightly add to the resistance of the boat through the water. Worth trying anyway.

The question of stability in model boats is another subject tackled in the current Model Boats Construction Special Issue as many modellers experience similar problems to yourself.

Colin
11 May 2011 at 10:29 #30583
Muhammad Awais
Participant
@muhammadawais53838
thanks colin for your review.. i’ll come up with my new design very soon

regards

Awais
12 May 2011 at 10:32 #30585
Bob Abell 2
Participant
@bobabell2
These are the airboat proportions

Bob
13 May 2011 at 04:28 #30596
Muhammad Awais
Participant
@muhammadawais53838
would u please suggest me a light and water resistant material for my next model?
13 May 2011 at 08:30 #30598
Bob Abell 2
Participant
@bobabell2
Hello again

I would suggest you start with a proven design

Take your pick from here……..

http://www.myhobbystore.co.uk/browser/995/hydroplane

All the best……..Bob
13 May 2011 at 08:38 #30599
Bob Abell 2
Participant
@bobabell2
The plans I suggested are mostly Vic Smeed I.C. powered designs and may not be suitable for electric power and RC

Sorry, but still worth a look?

Bob
14 May 2011 at 11:02 #30608
ashley needham
Participant
@ashleyneedham69188
For a fairly flat model such as an airboat I would use thin ply, 1mm or 1.5mm, or even lite-ply 3mm. Ply has the advantage over sheet balsa in that it it much more knock resistant and also it is easier to get a smooth finish in it for paint.

However, card can be used, if finished off with a coat of epoxy resin, or ezi-cote …may need a bit more internal bracing tho`. Use balsa for this.

To widen your first design, the easiest way would be to use expanded polystyrene, or Blue styrofoam, The blue stuff is good as it is easy to sand smooth and can be epoxied, or use waterproof PVA, as long as it is well sealed with paint..

or even…..

well, its a sort of skimmer….ok, it doesnt skim that much…if at all really

Ashley
14 May 2011 at 13:50 #30611
Muhammad Awais
Participant
@muhammadawais53838
to make balsa or ply water resistant, what material do u use?
14 May 2011 at 13:51 #30612
Muhammad Awais
Participant
@muhammadawais53838
in my last model, i used furniture filler which was pretty messy and the finish was also very bad but it did work.
15 May 2011 at 16:05 #30632
ashley needham
Participant
@ashleyneedham69188
Muh, use cellulose sanding sealer or clear dope, both available from any model shop..or of course simply paint it !! a drop of dulux will keep the water out easy.

A resin finish can seal and harden, epoxy resin or ezi-cote (or something) and I have use Ronson wood hardener to good effect, this is meant to harden dried rotten or soft wood before painting/filling and is a very thin resin to penetrate the wood and hardn it off.

The sanding sealer will soak into the wood/card/whatever very well, as will the dope, or thin down some standard household undercoat a little bit.

Furniture filler… do you mean filler for the gaps or surface sealer…

I use car filler…P38, usually for larger gaps and car knifing stopper (or small tubes of various trade name fine cellulose fillers) for hairline cracks.

Various fillers available from model shops as well.

Ashley
27 May 2011 at 14:29 #30763
Muhammad Awais
Participant
@muhammadawais53838
this is really informative but i wonder if i could find these materials in my area easily :’@
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