Hey Dodgy, thanks for the idea number 3, I will surely try that! And I hope this will work insha allah!
And those links will be very helpful. I hope those silicone are strong 💪💪

The couplings you appear to have are noisy as they are built to rather generous tolerances but if you can find a piece of rubber of a sufficient diameter you can cut a narrow band and put it on the coupling at the point where the pins are. I used this method on my converted Southampton and it is still going well with a much, much reduced noise level

1 - I concur with figtree7nts. You don't want a long length of unsupported floppy tube transmitting power. You will see that my illustrations show the unsupported tube to be very short.

2 - You also want thick tube to transmit power. if you have thin 2-3mm tube that will easily kink. I make my own connectors at the ends of each shaft to bring the internal tube diameter up to about 6-8mm.

3 - if you want to try a quick fix for what you have, I would suggest putting a small piece of wood or plastic inside the unsupported section of your tube, which will stop it collapsing when it is twisted. This may work if the torque is not high. And it's a quick, cheap thing to try.

4 - if you want to try making your own, you could get something like this - check the correct shaft size - https://www.ebay.co.uk/itm/Brass-Hexagon-Flexible-Coupling-Coupler-Connector-Motor-Model-Car-Boat-3-8mm/302549582190?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D20170221124951%26meid%3Ddc345e0eff7a498aaf6d1efe0039d818%26pid%3D100643%26rk%3D1%26rkt%3D1%26%26itm%3D302549582190&_trksid=p2045573.c100643.m3226

or this: https://www.ebay.co.uk/itm/Coupling-Inserts-for-RC-Models-Various-Sizes-available-RC-Model-Boat-Fittings/322996589219?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D1%26asc%3D20170920101022%26meid%3D7c9c41e4b98047af9227e21aef42a96e%26pid%3D100010%26rk%3D4%26rkt%3D9%26sd%3D191479721852%26itm%3D322996589219&_trksid=p2047675.c100010.m2109

and then buy a length of something like this - https://www.ebay.co.uk/itm/1M-Food-Grade-Clear-Translucent-Silicone-Tube-Beer-Milk-Hose-Pipe-Soft-Rubber/253549582415?hash=item3b08bb984f:m:mLOWX25B4-LemH4pL11iYfA:rk:12:pf:0

checking the diameters that you need, of course...

Here is a similar Eezebilt to your craft. it's the OSA Missile boat. You can see that the unsupported length of silicone is short, and this boat at 32 inches takes quite a lot of power...

Thank you Ed! I will try better this time. This helped me a lòt, learned some great stuffs. I will show you when I do that!

Hi Sakibian,

Why don't you push the motors closer to the shafts!
Maybe this will help with the misalignment of the shafts!
Or even try to move the motors so they do align!

Cheers, Ed

Thank you dodgy!! I needed this. I was always telling myself that a slight misalignment is okay bcz I'm going to use flexible coupler, so it's okay.
There I might have done something wrong!
Can you please give me the link,of that silicone tube that your using? Or I mean what kind of tube they are, where they are used😊
And yes I ment a lot vibrations by earthquake. Sorry for that.
At first I used some thin silicone tubes also, they weren't great.🤐

This is the boat I was trying to finish, Ed! I'm not very accurate at these so I face this problems. I'm quite young so when I build, I do hurry sometimes. I think this is my biggest fault when I do modeling.
The motor shaft is 2mm and the drive shaft is 3mm.
Thank you for the link ! Can you help me a bit more to know which size they Are? I can't find anything about the hole size they are having🤔

Thanks DodgyGeezer,

That was Coupler was what I was looking for.
As a recommendation to Sakibian!
But couldn't find it!

Sakibian,

Should deffinately use a coupler like that!

Cheers, Ed

I'm not sure what you mean by 'earthquakes' - do you mean there was lots of vibration?

The prop-shaft and the motor shaft should be aligned as precisely as you can manage. Though a universal joint will accept some misalignment, you should aim to get things so precise that there is no need for a joint!

That tube looks rather thin. I use tube which is 10-12mm in OD, with about 3-4 mm thick walls. You are correct that I 'make the shafts larger' by putting little knurled knobs made from aluminium bar on them. if you do not have a lathe, you can buy similar couplings like this: https://www.cornwallmodelboats.co.uk/acatalog/Robbe-Flexible-Coupling-3.2-4mm-R1445.html#SID=1586

Hi Sakibian,

Why can't you use couplings from Cornwall Model Boats!
https://www.cornwallmodelboats.co.uk/acatalog/Universal-Joint---Red-MA5000.html#SID=737
Maybe you can take a picture of your project to show us.
What you are working on!
I think the shaft should be close to the motor.
Or the rubber hose will tear!
Try looking for plastic tubing.
Of the diameter you need!
Or harder rubber tubing....


Regards, Ed

Are those fuel pipe? And you must have used something to make the motor shaft thick so it matches the tube, right ?
I had these but no fun. They are like earthquakes

These are the latex tube I bought from Ali express.kind of flexible rubber tubes,strong but not extreamly string. Used them on some places , fast spinning motors doesn't match. But my tug works well.
The problem is where I live, there's no hobby shop here. The closest is China. Think that! I live in Bangladesh 😊

Universal couplers work well for me any boat model shop has them
Rick

I am not sure that you mean 'latex'. The most usual soft tubes are silicone rubber. Not neoprene, as it is usually too stiff.

There are all sorts of universal joints available. Here are some metal ones from Ebay: https://www.ebay.co.uk/itm/5x-RC-Model-Boat-Robot-Universal-Joint-Shaft-Coupling-Motor-Connector-2-5mm/253848013746?_trkparms=aid%3D555017%26algo%3DPL.CASSINI%26ao%3D1%26asc%3D55149%26meid%3D95631f1d170a4b7294c22a48e8978fa2%26pid%3D101006%26rk%3D1%26rkt%3D1%26%26itm%3D253848013746&_trksid=p2045573.c101006.m3226

These are surely too strong for small boats, however. The Eezebilt range are typically 30-50cm long and I use silicone rubber joints on brushless motors there quite satisfactorily. You just need to be sure that the tube wall thickness is sufficient - typically 3-4mm.

Here is a picture of the Eezebilt PT Boat (50 cm long) motor connector, with a picture of it running. You will see that it can go at a reasonable speed. See http://www.eezebilt.tk/PTBoat.html