Dubbel bouwverslag Eezebilt pt boot

Hello Egon, Is the forward end of the tube fixed in the hole in the frame or is this more or less a loose end? The motormount looks not very stable and will allow vibrations. The hole in the tube you use for oiling/greasing the shaft? In this situation the oil will flow astern and hold back by the water. In fact you have to solder a piece of pipe on the hole to get some "oilpressure" on the tube keeping the water out and get some oil to the front bearing.
It's better to mount the motor on a frame, glued to bottom and sides. And use all mountingholes in the motorframe. It's quite a long end between mountingplate and coupling and this will allow wiggling. It's a bit difficult to explain in English, but hope you will understand. If not send me a personal message or a mail. Success. Rgds, Klaas.
 
It is not fixed, but maybe its better when I fix it to the frame? Tomorrow I will solder a piece of pipe on the hole. So it is better when I glue it to a aluminium motormount, I will buy it this week.
 
You need a big propeller with this motor. I think that a lot of the noise is the motor overspeeding with very little load on it. I used a 32mm 3-blade prop on the original - I would have used a 35mm prop if there had been space. I am glad to see that the boat is moving a lot faster - too fast for that pool, indeed! A big prop will slow the motor down a bit and that will be quieter.

Here is a picture of one of my prototype builds. Things to note:

1 - the motor mount is strong metal, and bolted firmly down on a wide base to cut vibrations. You use a vertical wood mount - I think that is vibrating towards bow and stern while running, and adding to the noise. Triangular fillets would improve this - or a new mount, as k-k suggests.

2 - I use an own-design connector which is designed to suppress vibrations - the universal joint ones are good, but I find they tend to rattle when they wear...

3 - The cavities in the boat are filled with flotation foam. This is a safety feature if the boat is holed, but it also absorbs sound directly, and stops the balsa surfaces acting as a loudspeaker and amplifying any sound.



IMG_2878.JPG
 
k-k zei:
. It's quite a long end between mountingplate and coupling and this will allow wiggling. It's a bit difficult to explain in English, but hope you will understand. Rgds, Klaas.
Klik om te vergroten...

Dan zeg je het toch gewoon in het Nederlands, kan die er zelf een vertaling op los laten.:)
 
Egon, I guess a multiply wooden frame will do and fixing the front end of the tube in the frame. That will iliminate a lot of vibration. As outrunner the motor, in combination with the ESC, will produce some high frequent sound. You can compare this running the motor disconnected from the shaft. That will give you an idea what sound/noise is normal. Rgds, Klaas.
 
That's up to you Egon. Probably a little piece of plywood glued to the frame will do the job. Rgds, Klaas.
 
Should I replace the frame or should I just reinforce the old one?

It is important to support the prop-tube as much as possible, but you don't have to have it supported everywhere. You can see that my prop-tube is supported at the frame, but then not supported beyond.

You can easily see if the prop-tube needs more support by putting a scrap of wood between it and the sub-deck to give it a bit more support. Don't jam it so hard in that you bend the tube! If that cuts vibration, just cement the support in place.

Adding windows to the superstructure will also help to cut down the noise...
 
Egon,

Als ik jouw motor- en as montage zie denk ik dat daar nog wel wat verbetering in zit. Probeer de schacht zo veel mogelijk van voor tot achter te ondersteunen zodat die niet kan wiebelen. En probeer je motor zo goed mogelijk in één lijn met de as te krijgen, de koppeling lijkt nu een kleine hoek te maken tussen as en motor. dit levert ook extra herrie, en aandrijfverliezen op.

Deze propjes, zijn dat standaard 3-blad propjes of heb je propjes gehaald voor snellere boten? Die hebben namelijk een wat grotere spoed (de bladen staan schuiner) waardoor ze beter werken op hogere snelheid. Ik heb het gevoel dat je tegen de limiet van je propjes aan loopt.

Het begint wel steeds beter te worden!
 
Ik denk dat het standaard propjes zijn, ik zal eerst de verbeteringen aan de as en de motorsteun toepassen en dan zal ik zien welke verbeteringen aan de prop nodig zijn.
 
The vibrations are much reduced now, but the sound stays horrible.
The boat is indeed a little bit too fast for this small pond and sometimes she hits the edge of it, but this is just for testing, when everything works properly I will go to a bigger pond.
 
Well I must say although it is a bit too small for a fast boat, I would LOVE to have that as testing pool


I might even let the kids use it in summer :D
 
Check that you haven't got something touching a rotating part. Sometimes you can get a wire being pressed down onto the motor or connector when the superstructure is on.

Put some slabs of foam either side of the motor, and add clear plastic to the windows. The boat may be resonating and amplifying the sound, then passing it out through the windows.

When turning, your boat can almost go on its side. On a big choppy lake this could be a danger - it might overturn. My original boat had a very sharp turn too - I cut down the rudder to change this. The rudder I use now is 2.5cm tall by 1.5cm wide....
 
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