By the way, Mobile Marine make an excellent alignment tool that can fit a whole lot of shafts and motors.
See link
I have one but lent it to a 'friend' still waiting😠😠
Regards
Ian

Neil,
The other factor is that is, if it whines it must be running! Sometimes an achievement with brushless motors.

I've followed several suggestions Rowen and all have proved the whine remains no matter what. I thought it was an issue as the brushed motor I had before did the same sort of thing. It did however prove to be a badly misaligned installation from previous owner. So I've chased a problem based on rhis fact to one that wasn't really there however removing the old mount it has shown anorher misalignment. So good in one sense just need solve it now with the new mount 😊

Slow and steady ... 15 years is definitely slow Martin 😀
Although working through lockdown it has focused the mind on how distracting life was beforehand.

Sorry to hear of your trials and tribulations, but it means I am not the only one who has learnt the hard way about the importance of correct alignment.
Once you have got it right though, think you may still experience a whine. Brushless motors are inherently noisier that brushed.
The consolation is they are much faster so the noise will be out of earshot quickly!
Rowen

Hi Neil,
With a bit of tinkering and a little time you will sort that mount out.
Slow and steady bit at a time.

Martin555.

Hi Martin
I think its a combination of my inexperience when I reinstalled the shaft as the glue had perished on the previous one. This now makes things all a little bit tight as I think the shaft is too far in the boat if you know what I mean see photo. Also the brushless motor xmount is a bit to small for the motor mount front plate see photo. I do like the idea of the mount and I'm thinking of trying to remake the front part of the mount. Well I would if I could find the countersink screws for the x mount 😂
Ian the whole alignment and installation of the motor has been a nightmare not only for me but everyone else on this site .... now you as well 😂😂

Yup
Alignment is always tricky I normally make a dummy out of Aluminium turned and drilled on the lathe got about 6 now.
As an R/C Aircraft builder, SLEC is always top class and helpful too.
Screws always get lost (Normally the small ones!)
Tip with epoxies I find useful is to make sure when mixed colour is even also check what it can glue as they are now sometimes specific (AS I have found out) Another thing is temperature. Genuine Araldite is bloody good stuff.
Good Luck

Hi Neil,
Is it possible to reduce the height by sanding and filing, or even cutting if necessary ?

Martin555.

Well motor mount from SLEC turned Friday not bad for a tenner and delivered in 3 days. As it looks better then the 'wing it mount I put together and the issues its causing I decided to change it.
Wasn't looking forward to it as I couldn't remember how much glue I had used to stick the supports to hull. Didn't matter as I obviously can't mix araldite as the supports just popped off. I was then left with what looked like toffee which easily came off.
When using the SLEC mount as designed it proved to be too high and didn't align at all with the shaft. Also couldn't find the countersink screws for the x mount so thought I'd adapt it a little.....winging it again.
It did however show what could have caused some of the problems as when using the alignment coupling it shows the shaft to be installed at an angle as per photo. So I'm going to give it a go using the motor mount I used before but fix it this time with nyloc's so hopefully providing a more sound solution.
I shall use a bit of servo tape as Ian suggests to isolate it a little.
Fingers crossed this time.🤞

What I did for insulation was that the motor mount has some thin Tamiya Servo Tape under it. Motor is still bolted down but decreased the motor noise slightly on my brushed motor

Hi Martin
That is it exactly the same sound except no low notes as Robbob pointed out which also tie in with your soundbox theory. I've hopefully got a new mount coming so will have a look this weekend with the home I didn't use loads of epoxy on the 'wing it' mount I put together.
Ah ah thread lock that'll be missing then on my prop 😂😂
Cheers Neil

We will need to see a photo of your Prop setup but it sounds as if the locking nut was not tight and no thread lock has been applied.

Martin555.

Hi Neil,

Firstly i must say i have no experience with brushless motors but i have been looking on utube and it appears that they do have a natural whine.

My approach to this would be to remove the motor from the hull and bolt it down to a solid lump of wood or bench then test it to see what the natural sound is.

I would then completely remove the old motor mount and replace it with a new one making sure there is no air gap between it and the hull.

Fit the motor and test again ( remember this will sound louder as effectually you are putting your motor in an empty box)

At this point you will need to decide to add insulation or replace the motor with a different one.

Maybe other members that use brushless motors can confirm the sound.

Sorry i could not help more, but here is a video of a brushless motor sound.




Martin555.

So this one is for Martin555 to eliminate any issues with alignment i think was the idea. I believe it could be OK as the motor sounds the same in this video as well.
I could be wrong as after watching the videos a few times now the motor sounds exactly the same 😂😂.
Any thoughts guys

Car service day and day off so only seemed right to have a splash around in the bath 😂
Before I went started videoing I decided to see what it was like going forwards and back which to be honest bought a smile to my face. Well until the prop fell off!!!!!! I love this boat.......not
Anyway screwed it back on but not sure why it came off and I know I'll have an answer soon so no panic👍
Next to video the action and results are at the link. To be honest I don't believe it was at full throttle as I stopped when the bath started bubbling and the boat was trying to get out 😆. There's some power behind that little motor and the water pick up works 😂😂😂
It does sound a little better but I think the vibration and low tones are still there - what do you think guys?

"There's really good stuff on the krick website "
That's why they are my main supplier here Neil.
There's lots of good suppliers in UK as well though👍
Cornwall Model Boats, Component Shop/Action Electronics for example.
I use them and similar when their products are not available here, Germany.
Easy way to find out if your batt is 2S or 3S-
Measure the volts on the large plug;
7.4V = 2s, 11.1V = 3S.
Or, look at the little white Balancing Plug attached to it_
There will be one black wire for the negative contact, and one positive wire (various colours depending on manufacturer) for each cell.
3 Pins = 2S, 4 pins = 3S.
I trust that you have an appropriate charger with balancer connection!!
Just 'blew up' your pic so I could read the legend on your battery properly.
You're right👍 It is a 3S 11.1V nominal.
The big 2.2 on the label refers to the battery capacity; 2.2 Amp-hour (Ah) =2200mAh.
Keep the questions coming😉 That's what we are all here for 😊
There's loads of 'Bin there, Dun that' guys here willing to help out.
Cheers, Doug 😎

There's really good stuff on the krick website much better than in the UK I would say so thanks for pointing it out. The minimum could be a COVID thing as they charge delivery on top I think.
Had a look at the battery and there's a black dot by the 3 cells 11.1v so presuming its a 3s and not a 2s although the 2.2 is confusing 🙄. So hopefully I'm good to go and standby for another set of questions on the transmitter got three so far to torture you all with😆

Hi Neil,
Sorry about the min buy of €20, never seen that🤔
But then I wait until I need a batch of 'stuff' to reduce or eliminate the shipping costs😉
Krick is my main supplier here. I just ordered a batch of wood and plastic supplies and some more EzeKote resin. Should be here by the end of the week latest.
Maybe you could go back to your original idea of twin props and buy two!!😁
See if you can find the coupling through a UK dealer.

"does this mean the motor I have is OK for what I need? Also included a photo of my bits 😂 which seems pretty much all the gear no idea😉"
The motor should be more than OK, a good compromise between torque (= low Kv) and speed (= high kV). BUT: not with a 2S LiPo battery!😮
You will need a 3S at least, but I note that your ESC is only rated up to 3S.
Here you can see the results I got testing my little Sea Scout with 7.2V NiMh, 2S (7.4V)LiPo and a 3S LiPo. Only the 3S gave acceptable results with power in reserve.
https://model-boats.com/gallery?q=Sea%20Scout
You can see all the gory details of my Sea Scout restoration and upgrade here
https://model-boats.com/blogs/28209

"whats the circuit bread board for ? "
That's just a chunk of Vero board to mount the main power switch (illuminated when on) and a blade fuse holder. Both from the car parts shop. So nutt'n fancy😁

Ref the SLEC mount; thought you would have some spare wood or alu in the stash box to build your own! I plan to use the dwgs to make a few from alu or 2 - 3mm plasticard, in various sizes depending on the model and motor(s) to be fitted.

BTW Never seen an i6 like that before!!
I use (amongst others) the German branded version from Conrad here, called REELY HT6.
Yes REALLY!😮 See pics, identical in all respects to the Fly-FrySky, Tgy versions.
See attached pics of three versions of the i6 that I know.
Cheers, Doug 😎

Doug on the photo of the motor with the silver Hull being nosey whats the circuit bread board for ?

Regarding my present mount which as you say could be salvageable I contacted SLEC to enquire on price for the same type as Robbobs. They came back at £11.45 delivered which is laser cut for their version of the Crash Tender. Not spending much in lockdown just work home work so ordered it this afternoon 😊.
Will post photos when it turns up.

Hi Doug thanks for all the links and I've had a look see but the minimum buy is 20euros which doesn't touch the coupling and mount - bummer.
On your post 'that motor should have enough reserve for your boat at more reasonable speed' does this mean the motor I have is OK for what I need?
Also included a photo of my bits 😂 which seems pretty much all the gear no idea😉
I've also ordered a set of feeler guages just to check the clearance which with 5 to 10 thou I maybe able to use the same coupling as the one Robbob uses

PS Here's the link for the spiral coupling Neil.
You can get it with various inserts to cater for the usual range of motor and propshaft diameters.
Cheers, Doug 😎
https://www.krickshop.de/Accessories-Spare-Parts/Accessories-for-Ship-Models/Shafts-Couplings/Stegkupplung-kpl-3-17-auf-4mm.htm?shop=krick_e&SessionId=&a=article&ProdNr=63902&p=192

Neil,
One final (?🙄) thought!
You mentioned you had about 1mm play in the propshaft.
Reduce that to about 5 to 10thou, with a thrust washer at both ends.
This will prevent the prop pushing the shaft forward and compressing the UJ in the coupling.
That may be causing some grinding noises which are then transmitted to the hull sounding box through the motor mount!
That's why I like the spiral couplings - they are silent😊
Rob's rubber coupling would be as well.👍
I gave up using UJ couplings years ago.
Cheers, Doug 😎

"I love the idea of the Krick mount which with a bit of winging it I reckon I could make one of those 😁"
Like this Neil? 😉🙊
This is from a 400 size, same as your motor.
I have the original Propdrive version of the 2830 1000kV in my Sea Scout.
It sits on a ply plate glued and screwed to two transverse beams attached to the keel.
All I hear is the high pitched whine of the motor.
No low frequency rumblings and grumblings!😉
Coupling is a flexi-spiral from Krick.
ESC is a HobbyKing Quicrun 16BL30, battery 3S LiPo.
Prop 30mm 3 blade brass Raboesch.
Sea Scout is smaller than your boat at 24" and lighter I expect at only 2kg all up.
But she goes very well planing at much more than scale speed.😌
So that motor should have enough reserve for your boat at more reasonable speed.
My excuse is a need to outrun the swans😉
Sea trial vids in the Gallery and Build blog here.
Cheers, Doug 😎

Hi both quick update just phoned SLEC to see how much they could make one for. As you know they sell the Crash Tender so worth an ask I thought. Also gave a shout out for the forum and your current blog - Robbob.
If its too expensive I love the idea of the Krick mount which with a bit of winging it I reckon I could make one of those 😁

Hi Neil,
You can get something very similar from Krick.
Fully adjustable and comes in sizes from 400 to 900 size motors.
Cheers, Doug 😎
https://www.krickshop.de/Electronics-Motors/Engines-Electric-Motors/Electric-Motors/Motor-Mounts-for-E-Motors/Motor-mount-400-shipmodels-adjustable.htm?shop=krick_e&SessionId=&a=article&ProdNr=63920&p=356

Hi Neil.
Thank you for your kind words.

My attention to detail comes at the cost of working very slowly by comparison to others 🐌.

The motor mount in the pictures is part of the SLEC Pilots Boat kit so it's doubtful that you could buy one separately. There are various plastic/nylon and metal mounts for brushless motors available but they don't have the adjustability of the one you see.
Perhaps you could re-use the metal one that you have but beef up the wood structure that you mount it on, and try to fix it to the keel or bulkhead rather than the bottom skins which is the 'sound board' that I described.
Rob.

Robbob can you buy these or did you make it being the extremely clever chap you are? You blow me away with the level of attention to detail you include in your builds.

Hi Neil.
Here's a 'photo of the motor mount in the Pilot Boat kit I'm building at the moment just to give you an idea of how that one mounts. You'll need the 'cruciform' mounting plate that should have come with the Turnigy motor though.
Robbob.

Cheers Colin and Robbob liking the suggestions made and I'm now thinking before diving in and it taking apart to do the easy tests as suggested.
Once the coupling is off then test the mount and base for stability and check with shaft alignment tool.
If not looking then to go searching on how best to make a better engine mount platform.
Any one got any pictures 🤞
Thanks Neil 😊

Hi Neil, just read through the thread and agree with the theories put forward.
I had the same motor in a dune buggy and you could hear it coming about 50yards away.
The only thing I could do was to change the motor to an inrunner.
Hardly a whisper.
But thinking about the boat, you could add some sound deadening material to the Hull sides, thin foam could work. Also once the Hull is enclosed it will be a lot quieter, and even more so on the water.
Cheers Colin.

Hi Neil.
Don't give up on it yet 😮.
It's hard to say if the way you have mounted the motor is causing the noise.
With the coupling disconnected is there any movement of the motor on its mount at all?
If there is you might consider re-making it so it's firmly fixed down and can't move, but make sure the shaft is properly lined up. I use a rigid alignment tool that ModelBoatBits make and then replace that with the actual coupling when the motor is bang on.
Robbob.

So I've been mulling over the whole fiddling analogy from Robbob and I reckon you've nailed it.
On looking tonight the engine mount is not really a mount at all more of a float as can be seen in the photo. When I made the mount it seemed a really good idea to glue some supports to the hull and then place and screw the angled mount onto them. Could there a possibility that the resonance is from the motor not being properly supported and the space under it is acting like a sound chamber. As the supports do not fill the whole space under the actual mount.
With all this in mind and me having no real clue what I'm doing how do I make a mount that would actually do the job?
One step forwards and twelve steps back anyone want a new project 😆😆

Neil,
Sounds like you have a good plan forward. I will have to say I have never heard that much noise coming from a brushless, a bit baffling!

Good luck, 👍
Joe

Well!
Fiddle me diddle and riddle me re,
Who's gonna try gagging liddle ol' me?😁
I'd just like to sa... Mmmmmm' MMM! 🙊
😎

Cue Doug with a fiddle related gag........🤣

Loads of excellent advice as always and I'm a much happier now. I was thinking it could have been a case of using Dougs famous Mole Grip twist and pull method on the shaft tube again 😁
So from what I'm getting its a resonance issue which if I turn it into a violin it'll go away 😂
But first off to try it in the bath no pond though as it is literally a hull with no deck at all 🙄. Then disconnect the coupling to see if the sound is related to the motor / mounting arrangements which may be dampened with a piece of rubber but realignment would be needed.
I purchased a flexible rubber coupling I think on your advice Robbob but it was longer than to UV type coupling and so prevented any free play in the shaft. It does look more of sturdy type coupling so did think of hacking a bit off the motor shaft as it is quite long or drilling out inside the coupling at the motor end. Thinking it will give some free play back. I really don't want to move the motor back if I can help it as it looks OK at present.
Thanks for all the help and will update tonight after work if I have time otherwise could be midweek.
Cheers Neil

Hi Neil.
Try running the motor without the coupling as Martin555 suggests just to determine any change in the noise, you may find that there is not that much difference. What I'm hearing is not too dissimilar to the sound of my Turnigy brushless motor running in my 47" Crash Tender when running it out of the water. I have the same coupling as you although I don't think that's adding much to the noise anyway and neither is the shaft running in the tube if it's properly lubricated.
BTW. I have started using a different coupling with a flexible rubber centre section and found them much better in all respects.

I think Doug is more on the mark with his hull resonance suggestion though.

My thoughts on this 🤓
A musical analogy..... think of the 'bridge' of a violin that sits between the strings and soundboard, the vibrating string (motor) transfers it's vibration through the bridge (motor mount) to the sound board (hull) which amplifies the sound of the vibrating string. In this case the large expanse of wood panels in the hull are vibrating, you can hear the harmonics as the motor speed changes. Out of the water those vibrating panels are un-damped but in the water they are, and the noise will be reduced to some extent.
When I run my big Crash Tender on the water it doesn't sound anywhere near as loud as when it's on the bench even taking into account the 'proximity'.
Brushed motors don't make so much noise because of the different way they work and a brushless will always 'whine' because of the way the motor is 'pulsed' as Doug explained.
Isolating or damping the motor mount with rubber probably won't make much difference because there will always be a mechanical connection if there are screws or bolts securing the motor through the rubber and the torque of the motor will possible case a misalignment to occur.
Just my twopenneth on the matter.
Robbob.

Hi Neil,

Do you still have a high pitched whine when it is not connected to the shaft ?

Martin555.

Neil,
One of the things that I do with all of my motor mounts is to try to isolate/dampen using rubber or foam. The thought is to lessen the transmission of sound to the hull. I buy thin foam rubber sheets from craft stores. Its 1/16" to 1/4" thick. I cut pads or washers to put between the motor mounts and the hull. On bigger brushed motors I build a cradle to hold the motor and the motor does not touch any hard surface, just the foam.

Joe

Hi Neil,
A high pitched whine is normal for brushless motors.
Due to the high frequency pulses sent to the motor by the ESC. Ca 8 to 10KHz depending on your ESC. Some older/cheaper ones with a pulse frequency around 800Hz sound a bit like buzz saws! But yours does sound very unusual, many low frequencies!
I suspect that much of the low frequency noise is resonance in the woodwork around the motor mount and the hull in general.
This should disappear in the pond when dampened (🙄) by the water surrounding the hull.
Your vid sounds typical of a 'dry' bench test.
Try again under load, in the Wet Stuff as Rowen says.
Cheers, Doug 😎

Have stopped using grease, prefer a light machine oil. Might be worth trying as it does sound a little unusual.
Have decided, from many hours spent trying to get brushless motors running properly, that until they are under load (such as in water), difficult to draw conclusions.
Have you tried load on the motor, or is it unloaded?