Hi all,
Thanks for all the advice and info, all very helpful to a newbie!
i certainly will install prop shaft supports on the 5mm shaft and get the correct size motor!

Thanks Again
Graham

Hi Graham, As DaveM says, he has worded it much better than I did. Hope it works out for you this time. Happy Boating. love to see some video of her on water once you have sorted her out.

Hi Graham
You do have to support the prop shaft close to the bearings at each end. This is vital if you are to avoid a slight imbalance developing into an uncontrolled whipping and as you have experienced, damage to the shaft assembly.
The support needs to be firmly attached to the hull and shaft close to the bearing to provide both vertical and horizontal support.
The supports should ideally be within 1/8" of the bearings.
If you are reinstalling the prop shaft then, as others have suggested, it may be an opportunity to move the motor towards the stern and use a shorter shaft, but still providing support near the bearings.

I think you might need pointing in a direction, so I had a quick look on Hobbyking, and this motor is the sort of thing you can use, although this particular one would need you to swop the shaft around, this is just a guide, other s will no doubt add comment, its the right size, 5mm shaft, right kv and watts.

https://hobbyking.com/en_us/turnigy-g15-brushless-outrunner-810kv.html

brushless esc

https://hobbyking.com/en_us/hobbyking-90a-boat-esc-4a-sbec.html

you don't need the high amp capability, but its reversing, programmable, water cooled, and has an sbec, so the main battery power this

5 mm shaft, move your motor to the centre section meaning weight distribution is more central, and you can now use a shorter shaft, and get a couple off plastic "x" props, I would say 40 to 45mm will be the one. This will give a good speed, and you can power on 3 cells or 4 cells lipo, get higher c rating (40c or more) and higher mah so you have fuel in the tank available

https://hobbyking.com/en_us/turnigy-battery-3000mah-4s-40c-lipo-pack-xt-60.html

This is just a guide, a starting point, as I feel you are unsure where to start, others with more knowledge will come in regarding this, having experience with lipo, brushless, 3 foot ply boats, and esc's, depending on budget, this would be the sort of thing I would be getting.

Hi Graham its at each end you need support to stop any whip on shaft

With respect Graham, A 'Keelson' is always inside the boat / ship. it is a reinforcing beam laid across the top of the keel. Nothing outside the hull.
Good luck with your fitting out and much fun sailing, Cheers Doug😎

hi Dave M,
well that was good info on the Lipo's i was going to put them in Parallel But certainly won't now! i will use one and then swap over when necessary as you suggest,Thanks!
As far as the 500 watt motor is concerned, i have not purchased it as yet but as a previous post stated that i need a smaller wattage than 500 , i will carry on looking for a smaller wattage and low KV size motor, although all i seem to find are are very powerful ones!
even on the web sites named in the post but i will phone them in the morning and ask.

the Boat does have a keelson, a piece of angled wood below the hull and also one inside the boat and this shows about 1 1/2" of tube either end of the shaft to fit the supports.
Thanks
graham

With you all the way down the line Dave 👍👍👍

Graham
That sounds much better and will move your boat at a very fast speed. I must reiterate my previous advice repeated by BOATSHED regarding the extra support for the prop shaft at each end and adjacent to the bearing.
Unlike brushed motors, brushless accelerate to their KV rating at a very fast rate and if your installation is not solid (as concrete) you will experience all kinds of problems, all costly, and often terminal (personal experience confirms this).
Finally do get a wattmeter and check the amps and wattage whist holding the boat in the water. if either are above the rating for the motor, ESC or battery you need to reduce the prop size.
I can't emphasize this enough as the consequence can be an explosion on the water and total loss of the boat and all its equipment.
Asw you have mentioned 10000 mA I assume you will be using two 5000Ma batteries in parallel. This is OK providing you use and electronic coupler between the batteries to disconnect a discharged battery to ensure no one battery discharges below the recommended value. These are not cheap and personally I would use one battery and change to a new battery when the first was depleted. I accept that if you are in a racing situation this may not be possible, but I suspect as a newbie you are using for pleasure purposes.
I hope you will now be able to proceed to install the new motor and prop shaft and supports as suggested.
Please keep us posted and I look forward to seeing your model on the water

That sound better with a 5 mm shaft. But still be sure to support the shaft under the boat and if possible also under the shaft inside the boat. This way you shouldn't have any trouble with vibration though the shaft to loosen it.

I think you've missed the point. Everyone has said you need less wattage . Ie under 500 watts and you've picked one at 500.Something about 440/50 watts tops is what you need.Even 350 would move your boat at a more scale speed with the right prop and a 5mm shaft. Have a look on Mantua models site ,Also Marine Model Supplies ,and Sussex Models. Oh yes also Wheelspin Models. if no luck ask Uncle Google.

Hi,
i have searched for a 500 watt 500kv motor and just can't find any, what company do you use for motors?
at last i think i found a suitable Motor, i hope, it's a keda 36-42m 500 watt 950 kv, with a 5mm shaft and fits my new 5mm to 5mm coupling, so don't need any other parts for the power train! will need to change the hole to hole distance to fit the 16mm spacing of the new motor.Then gluing the new 5mm Shaft in, i think thats a good setup.
The new 500 watt motor should have a long running time i guess on 10000 mah Lipo's?
Anyway thanks again for helping me, very much appreciated!
Graham

Hi Graham
If we are talking about the Graupner Brushless Speed ​​500 ECO no 7295
https://www.graupner.de/Brushless-Speed-500-ECO/7295/
then yes the Kv is 500 which equates to 7500 at 14.8v. it's 50mm x 80mm with a 6mm shaft so really a heavy duty motor and in a Aeronaut Queen 36" still much too big and powerful.
You really need to resolve the drive train and shaft problems and this will be easier if you choose a motor of smaller diameter and power. A 36xx or very similar size motor at about 1000Kv or less (500Kv with 14.7v) will be ample. The prop should be less diameter than the motor.
There are many examples of 36" model boats on this site and I do believe the majority of our members have used similar set ups, to those we have suggested, in their models with a large degree of success.
It could be we are talking about a different motor as you refer to " the small outrunner motor". if so please post a link to a pic of the motor.

Hi Graham, There have probably not been any answers so far because we are most possibly speechless.
If you go back and read through the comments above you will see that most of the problem has been the large overpowering of your boat (1690 Watts - according to info provided by DaveM), coupled with an inadequate drive train.
So with all this knowledge available you have asked our opinion of the Graupner 500ECO - one of the largest motors in that range. This is quoted at 1440 Watts. This may not rip the drive train out as quickly as the other motor did but has enough torque to do so.
In my opinion I think you could try a motor producing under 500 Watts and see how that goes - with a 5mm shaft.

Hi all, what do we all think of the Graupner 500 ECO? it only does 7500 rpm but high torque, about 1500 watts, 14.8 volts. The say it is especially built for boats. I would like to know your thoughts on the small outrunner motor?
Regards
Graham

The blade breaking above the hub indicates flexing of the blade for some reason.👍

the "roundy" bits are just for decoration by the way! and they are brass, just painted to look like metal

I was also told about cutting away the front edge for the same reason, digging in on turn's. I have found on hulls like the Vosper RAF Crash Tenders and MTB hulls they sit on the water on a turn as if they are stuck on the water no roll at all. Also on the Huntsman style hull they also turn a lot better with minimal roll. it was told to me on her the other day that the rudders were meant to be the way they are and there was no need to cut away the leading edge. I have done this for many years now, since the mid 70's and had great results I even put a 10cc engine in a hull rated for 5 to 7.5cc and it was an amazing boat to run. I turned a couple of boats upside down until the rudders were trimmed and then good to turn. I'm glad I have found someone that thinks it's alright to do. 👍😊

big pair of molegrips on it, and twist😁

regarding the rudder, I use standard profile rudders, and cut them this way. The rudders are like brakes, and I was having issues on fast gradual turns the bow was coming down, almost digging in. Thinking it was weight displacement I spent ages messing around, until a friend suggested cutting down the front edge, gradually, and seeing how it went, this cured the problem, turns are nice and flat

Hi Graham
I usually use the dremel to remove as much of the epoxy around the shaft, then get a big lump hammer and hit the end of the shaft to break the seal. Depending on how well you fitted the shaft it normally comes loose after a couple of taps and can then be tapped out from inside.

you could use a dremel and grind some away. I have used the brute force and Tapped the shaft inwards if a few taps aren't enough then a couple of harder whacks should do the trick to loosen it. then pull it out from under the boat. it has always worked for me.

Hi all,
Wow! so much info to take in, all excellent information though!
How do i get the old shaft out of the boat? it's well epoxied in down nearly the whole length!😤

Thanks again
Graham

Hi Doug
Brushless motors may be similar to AC motors in construction but they are powered by pulsed sequential DC so there is no AC involved.

I do agree Watt metres are the best way to make sure the motor, battery and ESC max values are never exceeded.

I agree the spec sheets are very useful but are specific to the type of motor and original supplier, and many are for companies no longer trading.

I do sometimes have difficulty in interpreting some of the info supplied but the nominal working voltage, max power are usually OK. The stall current is useful to decide on the wire and fuse size as well as choosing a suitable ESC.

At the end of the day if the set up is getting too hot you are probably working over the specs and if water cooling doesn't help you need to adjust the prop and / or battery voltage.

pmdevlin, I also see in your pictures that you have hardly any leading edge on your rudder, do you buy them like this or do you fabricate them yourself. if so then why ??

Great bit of information , Many thanks pmdevlin. I have only ever used 5mm shaft's and gone out with a variation of small to medium nylon prop's and played on the pond bank with them until I got one suitable. Then I would go for a cast alloy or bronze to that size. But this has been on IC engines, up until about 3 years ago. I have used the same way on brushless since. I have seen others using thinner 4 mm shafts and having problems. I have also always used a prop shaft support under the boat and if I have any type of gap between the coupling and where the shaft goes through the hull I would always add a wedge of wood epoxied in. Once again no backlash on the shaft to make it come loose. The only time I have damaged shafts has been through sheer stupidity racing round a pond with others and misjudging the distance and the bank jumps out and collides with the boat. Whoops broadsides with a nice hard concrete bank and, Yep new shaft needed. But as you say the throttle stick will take you from as slow as you want to flat out. Except when it's IC slow isn't always possible if you do not have a clutch fitted.

sorry to bore everyone with repeated info, as a similar question was posed recently. I agree with the fact that shaft is too thin, it very much looks llike a fibreglass very light racing boat set up, now this doesnt mean you cant go fast with your boat, but you need components that are up to lugging a big heavy lump of wood around the pond, not a lightweight feather😊

I have 5mm shafts, less whipping. and I have oilers so they are lubricated with oil rather than grease, just my preference. You can get these shafts from shg marine, they will supply with push in aceteal (probably spelt wrong!) water lubricated bearings, real cheap, so you can change then every season if you want. The shaft has to be supported, where it exits the hull, just put it through another piece of ply, and fill the void with epoxy, and double up the former thingy it goes through in the same way. (pic)
The prop you used is the wrong blade type, thats probaly why it fell apart, plus the soldered on blades are a weak design for higher speed, simon higging is one piece, but at this stage, still testing, you can get plastic "x" blade ("s" blade are less speed)_ props again from shg marine for a few quid each, then you can test a few different sizes. if you jump in for an expensive brass one, and its wrong, its wasted money.
As a starting point, 35mm, 40mm and 45mm, if you dont have any way of testing with data logging etc, you are doing short runs, with the smallest first, and seeing if the motor gets hot etc, and what sort of speed you are doing.
My brushless motors are generally 800 to 900kv, and achieve 25mph in four foot heavy hulls, you want lower kv for torque, not high kv high rev motors. I got into thsi 10 years ago, thwere was NO advice around then as it was new tech in boats so I learnt the hard way😭
When (if) you go to a brass prop, the "cleaver" blade design (pic) works well, I did extensive testing with my Huntsman and fireboat and was lucky enough to have Simon Higgins testing props with me on my boats, again because what I was doing, large scale boats, but going very fast, was unique, and the cleaver design was the best at the time.
Forget the fear of lipo, and brushless, they go as slow as your throttle stick is pushed, 👍

The bracket Canabus showed is the same as I described they work well.👍

Thanks Boatshed 👍
Maybe not nuts, just a little eccentric or pedantic? 😉

Brilliant Haig👍 I'll try that as well with my mini-cam and a Wattmeter such as Dave suggested.

Personally I wouldn't say you were nut's. it's people like me that are probably the nutty ones. Without your help some of us would be left in the dark with some of these small motor's. I do not understand how to work out the electrics. So your help that you give is a great thing for numpties like me. To buy a IC engine and stick in a boat was an easy task. But Brushless i'm lost. So many places have banned IC's we have to now rethink. Keep you help coming PLEASE.

Thanks Dave,
Eventually we will have put together a body of knowledge that model boat builders can use with some certainty. At present the information is sketchy, hard to find and sometimes ambiguous.

The motor designers and manufacturers have not been very helpful.

For my La Combattante iii missile boat I used two Hobbyking Keda 720kV motors rated at 215 Watts and 19.3amps max. They were the first brushless motors I tried. I was not sure how many amps they would draw, so I connected an ammeter and fitted my video camera so it read the amps whilst operating. At full speed they used only 8 amps each. Each of the batteries is from 12V made from 9 x NiMH 9Ah D Cells. I easily get over an hour run time at good speed. The boat is 1605mm long so not small. This information may help someone.

"The max current is the Max Watts divided by the Battery Voltage."

Hmmm! Dave, I=P/V works fine for DC and static resistances but it gets much more complex in a dynamic system like an AC motor, which is all a Brushless is. Don't want to get into rms and power factor and co here so I agree the wattmeter is the way to go to find out what's really happening.
Normally (at least here, not so sure with China!!) the max power output is quoted at nominal voltage and max efficiency.
If you (can!) trace the motors back to the original manufacturer they publish performance graphs showing efficiency, power vs current and volts. But who does that? Except nuts like me😉
According to the DC formula the ECO 600 would draw 131A at 11 Volts
or 97A at nominal 14.8V.
The real 'Black art' is then to work out what power you want/need for how much thrust, acceleration and top speed for a given boat and hull type🤔
Best way is to ask those who've 'Been there, done that'.
That's why I appreciated very much Canabus' advice when I was looking for a brushless for my Sea Scout upgrade👍
Happy sailing all - Whatever pushes your boat! Doug

Thank's RNinMunich, Dave M, canabus, reilly4. for the information you have added in your post's. That will be very helpful for me with a couple of boats I am hoping to get set up in the future with brushless motors. An Aeorokits Sea Commander, Sea Queen and an MFA Spearfish.

Hi Canabus, I think that's the same pdf I found👍
Snag is - you can't upload pdf's here🤔
You have to do what I did; Snip-It into jpeg pics and upload them.

BTW: attached are the dimension drawings to go with the spec. table.
Graham: table shows that the ECOs all have 6mm output shafts!

RE apparent discrepancy between powers of the 400 and 600;
same applies to the 200 and 300 so I don't think they are typos!
I assumed it has something to do with the construction/magnets (type and strength) or even timing?
Hope this helps untangle things a little😉
Happy Non-brushing all, cheers Doug😎
PS Dave: it is normal engineering practice to publish data measured at the quoted Nominal supply voltage - unless otherwise specified with the respective data.

Hi Graham and Haig
The max current is the Max Watts divided by the Battery Voltage. Most motors reach their max efficiency at much lower value, typically about 77%.

You need to take care when interpreting the data especially when the description has been translated from a foreign language.
The Eco range of motors were developed for model boats and in general were high tork, low revving and low current.
They were also designed to work at lower voltages so that would explain the lower Wattage.
I would only use the nominal voltage, Kv and max Watts figures.
The amps appears to be the stall current but I am guessing. Also we don't know the voltage at which the stall current was measured.

Providing you don't exceed the rated voltage and wattage your motor should be OK. I suspect running much above half the rated wattage may require some water cooling.

There are many Wattmeters available that will measure the wattage, amps etc at reasonable prices and if you connect in line with your battery and ESC whilst holding the model in the water you will have a good indication of the max current / watts at full bore. This should be ideally about half the max rating (watts & amps) for both the motor and ESC.
https://www.componentshop.co.uk/150a-watt-meter-and-power-analyser.html
Reducing the prop size will reduce the load.

Hi
I found this PDF on Graupner motors.
Also the Hobbyking site shows the specs on a large number of their brushless motors.
I am looking at replacements for two Graupner speed 600 7.2 volts for a mate.
I found a D3530/8 1700kv on Banggood with the same 5mm shaft and more grunt, less weight(74 grams against 192 grams)and about a third the price!!!
I am going to install one in a Sea Commander(34") with a smaller 2 blade 32mm CNC prop on 3S Lipo 3300mah to test it out.
Canabus

Graham,
I have attached the same table that Doug sent me. This has the relevant information you seek.

According to the table attached the Graupner 500 kV ECO has a specified output of 1440 watts and 80Amps. Strangely the 400 kV ECO has a specified output of 2010 Watts. So the 1440Watt output is questionable and may be a typo based on the other entries in the table. more likely to be 2440Watts

In any case you need a 5mm diameter propeller shaft.

For shaft alignment i use a brass tube that slides snugly on the propeller shaft and then on the motor shaft. When the tube rotates/slides well on both then the shafts are aligned. I then fit the motor mounts, check and tweak the alignment if necessary, remove the tube and replace with a universal coupling. if the motor or propeller shafts are a different diameter then I insert the relevant size smaller tube inside the larger of the tubes. This method is simple and has served me well, including for larger IC engine powered boats belonging to friends.

Haig

hi all,
so what wattage is the Graupner 500 ECO, can't find the Amps.
how do you know what ESC Amperage to buy?
Regards
Graham

Mon plaisir Haig, that's what we're all here for - ain' it? 😉
Happy sailing, Doug 😎
BTW: that's one thing I really like about the German suppliers, most of them give much more info in their on-line specs.
Funny; for years at work here I used to moan that our marketing dept. worried more about dB's and microvolts than about what the customer could actually do with the bl..dy box! 🤔 I used to rewrite the system specs My Way (thanks Frank!!😉) so the Admiral knew why he was spending his hard fought for budget!

Thanks Dave,
In common car language that is a V12 in a Ford Fiesta, with the Fiesta drive train.

In some ways I believe the brushless motor manufacturers/sellers are responsible for the confusion. Mostly we see the kV, physical size and the number of Lipo cells required. You need to dig deeper to find out the Watts. The kV basically gives the RPM only. No mention of amps and power. We don't buy cars and motorcycles based on the engine RPM do we?

Typically if you look at the reputed Graupner Speed Brushless range, they have low kV specs, but the differences between a 400kV 7.4V, 400kV BB 11.1V and a 400kV ECO 14.8V are 130W, 1100W and 2010W respectively. A huge difference. When viewing the on-line retail sites, including Graupner, they all look the same (maybe the same photo), but they are all very different motors. Without the rated amps and Watts (not published) the buyer is left unclear as to what they should buy. Brushed motors are more clearly defined.

I must thank Doug for helping me out with Graupner brushless specs when I required assistance.

RM. thanks for the propshop up-date, did not know of there problems, hope they are back in business soon, Simon at Protean, was propshop till he left, his range is superb.

Mark

Hi Reilly
the motor specs are here
https://hobbyking.com/en_us/watercooled-brushless-inrunner-3660sl-3180kv.html?___store=en_us
It's rated at 1690 watts and is far too high kv for this model.

Hi reilly, you don't have to go that far!
There's a dealer in Oz, Ringwood Victoria 😉
http://www.floataboat.com.au/products.htm
Cheers Mate, Doug 😎

I get my Raboesch propellers from Cornwall model boats - and I am in Australia.
It would be very interesting if there was a video made at the start of this post. How many Watts of power is that motor producing. That is the question I would have asked at the time.

Simon Higgins at Protean Design does a large range of props and M5 is no problem.

He used to be at Prop Shop.

PS
Deans Marine do Raboesch as well 👍😊
http://deansmarine.co.uk/shop/index.php/cPath/35

I recently bought their HMS Manxman kit and it came with cast brass props and excellent shafts & tubes. 😉

Hi Dave, yep, seems Raboesch don't do direct sails and the Jotika site directs you to the shipwrightshop for orders.
There they only seem (at the moment?) to have rubbish soldered props😡
http://www.shipwrightshop.com/shop/contents/en-uk/d7_RC-Ship-Fittings.html

I get my Rab stuff from Krick, they do the full prop and shaft range.
http://www.krickshop.de/Products/Accessories/Accessories-for-Ship-Models/Propellers-for-shipmodels.htm?shop=krick_e&SessionId=&a=catalog&p=186
Excellent service, I get my order usually the next day, max 3 days.
For 'other countries' they say 3 to 7 days for delivery, which ain't so bad😉 Just bought two 30mm M3 props from them to replace the nasty plastic things on my HMS Belfast. Ordered Wednesday - arrived Thursday😊Happy hunting, cheers Doug 😎

Hi Doug
Thanks for the update on PropShop.
I can't find a way to order from Raboesch, they seem to have agreed distribution with Jotika who have not yet set up to take orders.
The Raboesch web site directs me to the USA for distributors!
Cornwall Model Boats do stock so all is not lost.

Regarding propshop and other possibilities you could look up protean design on Facebook. He has some nice items.

And I would stay on 4mm shaft as you will get the largest range of props to choose from.

Hi
I use 4mm stainless steel shaft with a brass or roller bearing at the motor end and a Teflon bearing at the bottom.
Grease I use Dow Coring Molykote Compound 111.
A squirt in each bearing and install the shaft with a finger over the inner bearing( the air escapes via the oiler tube) and cap off the oiler.
I the picture is the shaft support on my Huntsman which is a slide fix for the prop shaft tube.

Canabus