Hi Ian,
"I have a toilet cistern needs a new seal. Cost to me 50p But I have to call a Plumber GBP 75.00. Just as well we have two bathrooms!"
Apart from a collection of ready made plumbing 'stuff' I have an emergency sheet of gasket neoprene plus a toob of silicone gasket goo😝
Have used for two cistern outlet valve repairs so far 😊
No way would I call out a plumber for something like that!
Cheers, Doug 😎

Hi Maggie,
Any progress?
How did you get on with your set up?
We're all on tenterhooks here!😮
Cheers, Doug 😎

I have started mine but we are on a severe lockdown in South Africa ( Covid 19) The hardware shops are closed except to registered tradesmen. I have a toilet cistern needs a new seal. Cost to me 50p But I have to call a Plumber GBP 75.00. Just as well we have two bathrooms!😊😊

Worth noting that solder melts at between 350-500 deg C!
Use fuses between batterie(s) and ESC

Hi Paul , Thanks , I will sit down and digest all the information / advice both you and Doug has given me plenty of ideas and solutions sadly as I have mentioned previously , it is looking very doubtful our Club will meet this season so will not be able to report back with the success ~ the only alternative to running at our club pond will be the Blue Water Club as they meet 24/7 ( obviously not in our current lock down situation )
Many thanks and any one reading this blog 'keep safe'🚤

"just a small logistical issue of powering the 12v sound units / pump"
No problem Ray😀 Just use a UBEC.
Here's a selection to choose from, just make sure it can deliver the total current your sound machines and pump need.-
https://www.amazon.co.uk/s?k=12V+UBEC&link_code=qs&sourceid=Mozilla-search&tag=firefox-uk-21
I rather like the look of the dual Matek version; one output for the RX and one for your modules and pump😉 Or the Hellery 8A version if you need more poke!
Here's a wider search!
https://www.google.com/search?client=firefox-b-d&q=ubec+12v+output
Happy hunting, and much success with the LC3536🤞
BTW That's the 538W motor isn't it?
If so current draw maxed out on a 3S should be about 48A,
on 4S 36A, and on 5S about 30A. so 12gauge should be OK.
I wouldn't go any thinner though. Fit a 50 or 60Amp fuse if you can.
Try it on a 3S before you shell out for bigger batts. 35 or 40mm prop.
You might be pleasantly surprised😊
Cheers, Doug 😎
PS Hope this isn't a 'bum steer' 😮

Hi Guys , thanks , you have certainly given me a steer ( apologies for the pun ) to use a selection of the Leopard motors , looks like the 1100KV outrunner is the one I should start with ~ can I use the 120amp esc I have and if so do I need to use 10 gauge wire to the battery or can I use 12/14 gauge wire
Again , many thanks for all the advice you have given me , it certainly seems I do not need to use the motor I have already bought as this is not suitable for my use ~ only problem is, the motors suggested are rated 3S to 5S , if I use a 4S or 5S power pack , just a small logistical issue of powering the 12v sound units / pump
Regards Ray

Hi Ray,
No sweat👍 We're just a coupla bin there dun that guys😁
Off the cuff, without looking for the specs, I reckon the LC4250-5T 960KV Outrunner should fit the bill. Surely you can squeeze another 4mm diameter in without great disruption?
Or perhaps the LC3536 -7T 1100KV Outrunner if things are really that tight?

The LC356?-8T 960KV sounds like the ones you already use?
If so try one of those and see how the boat goes👍
Try with your existing 3S battery first.
As you say you don't want to go racing (or emulate that Warp 'nutter'!) I'm not convinced you need to go to 6S. A trial will tell.
Cheers, Doug 😎
PS 45mm prop sounds good to start with so don't start tearing the boat apart😮
Leave the wiring as it is. 4mm connectors are the norm for bigger motors.
XT90s would be good but the 60s should cope as well.
BTW There are little jigs available to help with soldering a variety of connectors, incl. the XTs and bullets. Have a look through the site of any decent model stuff supplier who also does Tools👍 Also, one of these little Amp/Wattmeter gadgets can help to see what's going on current-wise! See attached link. Available all over the net for a few quid.
https://www.amazon.co.uk/4-8V-60V-Precision-Voltage-Analyzer-Backlight/dp/B07H7F2L43/ref=sr_1_fkmr1_1?dchild=1&keywords=KKmoon+150A+High+Precision+Power+Analyzer+Wattmeter&link_code=qs&qid=1586982381&sourceid=Mozilla-search&sr=8-1-fkmr1

Hi Paul and Doug ,
You are stars , you have both been very informative and explained the KV’s , torque and other specs of brushless motors which means for the first time I am starting to understand the properties / performance of a brushless motor . Unfortunately with the exception of our old Chairman ( who just buys a motor and hopes it works ) I am the only member of DMBC that runs brushless and therefore I have no one else to talk to to get advice . When I purchased the Model Slipway Tamar Life Boat I was told to contact Westbourne Models as they knew exactly what motors / props to use ~ and she runs perfectly , 2 x Thumper and 2 x 60 Amp fusion Esc’s neither water cooled on 3S Lipos .
When I race cars all I need to decide on is the Turns of the motor ( as all car motors are 540 size ) and the gearing ~ pinion and spur gear . I race with 120 Amp ESC’s
The model numbers are as follows :
LC3536 -7T 1100KV Outrunner Brushless Motor Leopard Hobby
LC3536-14T 560KV Outrunner Brushless Motor Leopard Hobby
LC356-8T 960KV Outrunner Brushless Motor Leopard Hobby
LC3536-5T 1520KV Outrunner Brushless Motor Leopard Hobby
LC4250-9T 480KV Outrunner Brushless Motor Leopard Hobby
LC4250-9T 550KV Outrunner Brushless Motor Leopard Hobby
LC4250-5T 960KV Outrunner Brushless Motor Leopard Hobby
LC5055-9T 430KV Outrunner Brushless Motor Leopard Hobby
LC5055-6T 650KV Outrunner Brushless Motor Leopard Hobby
LBH3650-9T 4370KV Inrunner Brushless Motor (2 pole) Leopard Hobby
I know that there are other companies making Brushless Motors ~ can you suggest any alternatives to the Leopard Motors
Yes the ESC is Brushless and will cope with 6S
I have already set the motor / Prop Shaft in place to take a maximum 45mm prop size
Also it will be difficult for me to experiment with any other motors that are bigger than 540 size brushed motor so model number LC5055-6T 650KV Outrunner Brushless Motor Leopard Hobby which is Dimensions (Dia. x Length：Φ50.0mm x 55.0mm) will not fit into the motor mount ~ if I was to use this motor then I would need to adjust the motor mount and take out the prop shaft to increase the rake
Yes the sound units and pumps will operate on spare channels at 12 volts
One other concern is the size of the wiring with all my other boats I use 14 gauge silicon wire with XT60 and 4mm bullet connectors . The ESC has 10 gauge wire to the battery and 12 gauge to the motor presumably the 10 gauge is to facilitate using 120 amps if I use the types of motors you are suggesting can I down size the wire as I am not sure that my soldering skills will be good enough to solder the 10 gauge wires to the switch / XT 60 connectors ( I do have XT 90 connectors ) , which if the joints fail , it could result in a short = possibility of a fire
It seems that you are suggesting to use 6S batteries ( 2 x 3S ) ~ as I previously mentioned if I was to use 6S power I would have to re think the hardware installation
Unfortunately, no one knows when normal life will resume so we have a possibility of real possibility of waiting till next year to sail her ( we use a manmade pond which is emptied during the winter to avoid icing over which could crack the cement )
Finally once again many thanks for all the help and advice you have given me , it is much appreciated ~ keep safe

great reply Doug, you got to the specifics there.

In Summary Ray,

keep your esc, its fine, but is it for brushless, and does it reverse? how many cells will it take?

motor, needs to be in region of 1000kv or a bit less to haul the heavy hull, and consider its only a single screw. size, Im not sure, poss 38 to 40 (the first two numbers of the spec of the motor, someone else can get to this)

if the esc is rated for it, run 6 cells, two 3 cell packs, minimum really needs to be 4000mah, and a good c rating, 40c upwards, or the lipo will drain too quick, and starting point for me would be cheap plastic "x" props, at 50mm, 52.5mm and 55mm to test.

5mm shaft, 4mm is marginal

Hobbyking is the best place, look there, you dont need to be buying expensice equipment when you are at this testing stage.

this will somewhat replicate how I arrived at my Huntsman set up, same size, similar weight, although the deep v hull of the Huntsman makes it handle very different.👍

Unless someone comes on with evidence of what they use, and the results, this is it. Have you looked at the boat harbour section, see what people have?
Paul

Hi Ray,
I agree 100% with Paul. (Good call Paul .. 😁)

1200W!? Sheesh, your boat could make a pot of tea on the side😂
Apart from Paul's excellent resume, let's take a quick shufti at some practicalities!
Assuming the 1200W is the input power from the battery, the current drawn at 11.1V would be around 108A, assuming DC, which it isn't - it's pulsed DC, but we can ignore the difference for all practical purposes. To simplify things let's say 100A.
A fully charged 100Ah battery can theoretically supply that current for one hour, but it's one helluva big 'eavy battery😮 Twice the size of my car battery!
Going to practical dimensions for a model-
A 10.000mAh (10Ah) battery (which also ain't a lightweight) will (theoretically) supply that current for about 6 minutes🤔 5000mAh for 3 mins and so on.
The 1100kV 538W job would roughly halve the max current demand thus doubling the endurance to a magnificent 12 or 6 min😉. (All this being based on max current input at Full Chat on 11.1V - 3S LiPo.)
The 550kV / 643W version might be the best compromise, for more torque (shove) as Paul says and reasonable endurance if you're not flat out all the time.
Try one of your 960kV 353W motors first, check performance and go from there👍
Let us know how it goes please.

BUT; whatever motor DON'T over prop it!
Bigger props often just suck more current without producing more performance.
Often exactly the opposite if you overdo it.
Rule of thumb is 'Prop diameter not larger than the motor outside diameter'.
Not so hard and fast as with brushed 'can' motors but a good starting point.
What size prop are you thinking of?

Re Power for other systems - irrelevant to choice of motor and drive battery!😉
You can always fit a UBEC to power other bits and pieces and tap off a higher voltage battery as Paul says.
Would help if you give us the model numbers of the motors so we can find 'em and check the full specs; voltage and current at max efficiency, stall current etc - if available!
If not I'd look elsewhere!!
I found the construction of the Leopard site rather weird and difficult to find specifics🤔
Cheers, Doug 😎
BTW kV just means 1000rpm per volt applied OFF LOAD. At 11.1V that would be a screaming 24,420rpm for your 2200kV motor🙉

Ray,

I could be wrong, but imo the 2200kv is way too high, lower kv will give more torque, high kv will give more revs, if you are saying the boat will be heavier than my Huntsman, which has a 900kv, then your 2200kv will just rev its nuts off! you need the torque to get it moving, and to spin a bigger prop, that high kv will not spin a big prop. You can run two 3 cell lipos, wired to double the voltage, but tap into one battery supply to power other things, so then they are on 3 cells, not 6. Also by splitting the battery source, you can balance the boat, as in the pic. I would imagine tyou will be operating the accessories on spare channels from the receiver, if that is the case it wont matter what your drive battery is.

Hi Paul ,

Thanks , I expect my Crash Tender will be slightly heavier than your Huntsman , but gives me a rough ball park .
I thought I would try and establish the specs of the combination I have already bought ~ it looks as if :
# ~ Motor is an inrunner 2200KV and 1200 Watt
# ~ The ESC Has a constant current of 120Amps and Burst Current 240Amps
The other problem is the battery as I was hoping to run on 3S Lipos ~
if I use a bigger battery I will have to rethink my installation of all electrics ~ Monitor Pump , Sound Units
Thanks again for all the help you guys are giving me
Regards Ray

The 3 props was an error! David Brown used to own Vosper in the 70's. I worked for DB at the time and managed to pick up a 3 prop design in the dusty archives but it was never brought to Fruition. DB still has the design of the gearbox for the three prop version! Obviously not put into production.

Hi Ray,
very difficult to answer really, as other things come into play, the weight of the boat, the propeller, and the speed you actually want to go.
Other will no doubt provide more clarity, all I ask is that if you get advise, make sure its proven and tested!

I can compare to my 4 foot veron Huntsman 28. Its heavy, and runs single screw, so similar in some ways. This has had a number of incarnations, firstly a graupner 700 bb turbo, 52.5mm "X" prop, 10 mins running, the motor was hot on 9.6v, and it was water cooled. A heavy boat wanting speed has a play off.
I then went to brushless in runner. 900kv, running off 6 cell lipo, faster at 22mph, 10 mins runtime, lipos depleted. I then went to a number of outrunners, as they were cheaper. At the time, nearly 8 years ago, there was no info for brushless in large boats, it was all trial and error.
I kept at the time copious notes, comparing voltage, props, gps speed, and found that no more than 1000kv, and 38 to 40 can size, with 52.5 to 55mm "x" props on 6 cells where the best. At 24mph the boat would be on the edge of torque roll.
Cant comment on watts etc, as I cant find my notes! max amp spike was 80a, so your esc will be fine as it wont get pushed, there is a load of headroom with it as you already have it.
Coincidentally I posted an old video of my Huntsman last night, it does however have a belt driven gear ratio reducer fitted, prior to the gearbox I was using a 800kV 40 size can hobbyking outrunner, with a 5mm shaft, 4 mm or less was whipping and bending
bit vague sorry!
Paul

Hi Doug and ‘pmdevlin
Thanks for the information I am really not happy to use the motor and ESC I have and wondered if you guys could give me advice on which motor I should use all my boats run brushless except the bow thruster in my Tamar Life Boat .
Most of my boats are 36” long ~ GRP / Plastic ( I have a fleet of 5 Arriva Boats that are wood )so the RAF Crash Tender being longer and all wooden is naturally heavier .
The person who gave me the advice to set my boat up with the 120Amp ESC and Inrunner Motor has a much larger pond than the one I use and his boats are set up for ‘warp speed’ which clearly I do not want ~ I would like to achieve a realistic speed .
I use the same motor in all my boats ~ 36”Huntsman ( GRP ) 36” Luxury Cruiser ( plastic ) all the Arriva range ( to include a Ferrari and Monaco ) and I get a good turn of speed and planning .
It seems to me that Brushless motors have 3 important specs ~ KV / Turns and Maximum Power
The motor I use is a Outrunner Leopard 8 Turn , 960 KV and Maximum Power 353 Watts
Other motors in the Leopard range are :
7Turn , 1100KV , Maximum Power 538 Watts
5 Turn , 1520KV , Maximum Power 370 Watts
9 Turn , 550KV , Maximum Power 643 Watts
5 Turn , 960KV , Maximum Power 823 Watts
9 Turn , 430KV , Maximum Power 1386 Watts
6 Turn , 650KV , Maximum Power 1411 Watts
9Turn 4370KV, Maximum Power 500 Watts ~ This is the only inrunner
I am using a single screw
If anyone can suggest the best motor for my boat from the above specs I would be most grateful
Many thanks Ray

Super looking model and a very good video. Hope mine ends up something like that.
Peter.

Well that's got to be one of the best.
I will have a lot of work to get my old 93 up to that standard. Great model and a fabulous lake.
Keep up the good work. Cheers Colin.

I like the video, she runs extremely well.
Thanks for sharing.

Martin555.

Thanks Guys
Not many model shops here in SA who deal with boats. One Hobby shop 40k's away (Aerial Concepts) They specialize in very expensive Jets, keeps trying to sell Outrunners to me with some very expensive Lipos. I need the 12volt SLA battery for ballast judging by Sea Queen

The best thing is an Amp Meter to check and Fuses. It's cheaper to replace a fuse! The reason for my 120 amps brushed controller is what's obtainable in South Africa. The 40 amp from the Sea Queen was a totally stalled motor! I don't recommend you rate at 40 amps and protect with a 20 amp fuse. My sea queen is happy with that and hasn't popped a fuse yet

Just as well I haven't installed yet. I am going on some very old sketches that came out of Vosper as I worked for David Brown in the 1970s the info wasn't clear then!

Hi Ray,
" I have spoken to other Members of my Club ( DMBC ) and they have told me stories of boats using such a powerful ESC , catching fire and the solder joints melting . "

Hmm! That simply tells me that your fellow members were very foolish not to have fitted suitable fuses in the system! At least in the + supply wire from the battery to the ESC.
If the motor is brushed then put a fuse in one wire from the ESC to the motor as well.
Doesn't matter which. Fuse value (Amps) should be at least 20% less than the stall current of the motor.
I would not place too much faith in those members advice on model electrics🤔

But, one step at a time!
An ESC 'rated' at 120Amps is 'supposed' to mean it can handle up to 120A motor current continuously. If it's an 'inexpensive' Chinese product I would take that with a large pinch of salt and derate it by ca 30 to 40% to be on the safe side.

It's the motor which draws the current not the ESC. But the output circuit of the ESC must of course be able to provide that current with some reserve as safety margin.
If the motor stalls, weeds in the pond fouling the prop for instance, then the current drawn can rise dramatically hence causing the pyrotechnics your members describe.🔥😭 Thus the requirement for the fuses😉

It would help us enormously if you told us which motor you have.
Does it have two wires (i.e. brushed) or three (i.e. brushless)?
You mention 'kv' which suggest a brushless motor.

Both being water cooled doesn't mean much (except agro with the installation!).
What matters is that the voltage and current handling capability of the ESC is man enough to cope with the demands the motor puts on it.
Which is why we need to know which motor and ESC😁
Make, model/type number? A photo can help give us some clue👍
Scan or photograph the spec sheets if you can.
Then we can probably give you more detailed assistance😊
I agree with Paul, can't see you needing a motor drawing 120Amps.
That's for the crazy racers!
I have a 1000kV outrunner in a 24.5", 2kg boat running off a 3S (11.1V nominal) LiPo.
I have never seen it draw more than 7Amps and it goes like stink and planes very nicely😊
So I fitted a 10Amp fuse. The ESC (Quicrun 16BL30) is rated for 30A. No cooling. No fiddly pipe work. Nothing gets more than barely warm😊
Cheers, Doug 😎

Hi Rowen,
" the Crash tender, had two props."
Dead right Sub👍
Driven by two Rover Meteorite petrol engines.
Specs attached.
Cheers, Doug 😎

On my Brave Borderer (about 36"), which has three screws, outer brushless (30mm dia) motors, and the centre brushed.The max current draw, per brushless motor, is under 30 A.
There is a video of it on this site and at max speed it is more that fast enough. Can get around 1/3 of the forward hull out of the water, which is unrealistic.
Cannot think on a scale vessel, with scale props and speeds, how 120A could be drawn.

Hi Ray,

not much info to go on there my friend, the 120a esc will not catch fire, these things happen when things overheat, and its unlikely you will have a motor that will be drawing more than 120a, as thats crazy high, so using that esc will never get strained. I cant see any info on the motor, so don't know if you are talking about brushed or brushless set up.
My Fireboat was twin screw, two brushless outrunners capable of 25mph, as I recall amp draw on fresh lipos (4 cells per motor) was approx. 60a and I doubt you will have anything like that set up, as I wanted silly speed and short run time. If you can give some extra info, maybe a pic or two, we will be able to add some more advise.
thanks👍
short video of me messing with sound units!

No, this vessel, the Crash tender, had two props. Many other RAF vessels though had three. Probably where the thinking comes from.

"and also installing three props as per the original."
I wasn't aware they had 3 props the pictures I have only show 2 props, have I missed somthing?

I have just ordered two MFA 850's for mine and actual consumption in amps is about 12 amps per motor Stall is about 40 amps ( According to my old and trusted AVO). This was taken from my 46" Sea Queen. As my 46' Crash Tender is under construction I will put a 120amp Speed Controller in. The Sea Queen is almost the same hull and runs very well. The idea of using two MFA 850's is purely to get a nice plane and also installing three props as per the original. Will need to play with props to see. As I have fitted 2 motors I have put in cooling coils on the motor Th speed controller has a massive heat sink with no cooling. The forty Amp installed on my Sea Queen measure about 45 Deg in an ambient of 25 so not bad. I always try and use brushed motors less cooling problems

Hi there doesn't the motor have its spec printed on the body, if not I'm sure that you will get great advice from members on here
PS not sure but I think the 120 amp rating for the ESC is just stating its max limit so a smaller motor should run OK, however wait for the experts to reply