Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[IanLloyd]

in the middle of refurbishing one of the two Sportsman boats I have and will soon be looking at a change in drive chain from the old 540 brushed motor and 7.4v nimh to something a little more modern. Can anyone suggest a suitable brushless set up as not too sure of where to go with this. Or maybe I should just renew the 540 with something similar but maybe larger and use Lipo power? This Sportsman is single shaft and to be honest I am not too interested in high speed just something that is suitable really.


Doing up the outside I do feel something needs to be done regarding modernising the power, or am I just being silly?

[unbuiltnautilus]

Not being silly. Brushed set ups are not expensive, and still have the edge in slow speed models. However, faster stuff, take the plunge.
My advice based on some testing I have been doing on a 37" KD Perkasa, is this,


http://www.componentshop.co.uk/lc3536-8t-960kv-leopard-outrunner-brushless-motor.html


I would suggest either 7.2v NiMh, above 3000mAh, or 8.4v NiMh, as before above 3000mAh, or a 7.4v LiPo, similar spec, 20C Rating should be fine. Prop at about 35mm to 40mm max diameter, and a speed control good for 30amps.
I tried various voltages and with a watt meter got some fairly economical current drains, certainly at the lower voltages. Speed was still fine for most ( not gas turbine equipped, 50 knot monster ) boats. I think 7.2v was about 8 Amps in the water.

[martno1fan]

Hi not sure how heavy your boat is ,the motor posted above might work but if the boats on the heavy side id go for something a bit stronger,this one works well in a  900 size fast boat on 6 s but you can also run it on 4 s lipo batteries and that should give more scale speeds.Id go up on the speed controller too anything around  80 amps then you know you dont ever need to worry .

http://www.radiocontrolinfo.com/information/rc-calculators/rc-boat-calculator/#Brushless

[IanLloyd]

Quite like the idea of going brushless, I run a few model cars and all are brushless and running on Lipo and they are brilliant so happy to go brushless. There are a few questions though. Are all these boat options sensorless, just that running cars sensorless is terrible compared to sensored as far as smoothness goes. Dont really want to use battery packs other than the 7.4v 2 cell Lipos I already have so really should be compatible with them. And speed controls, are they basically the same as the car ones I run but waterproof or are they something special to boats. I would assume the load is less in a boat?


As I said do not need massive speed but getting up on the plane would be good, low speed smoothness and control is very important.

[martno1fan]

You can use your 2 s lipos just wire them up to produce 4 s and your good to go,actually as far as load goes boats are under way more than cars as the prop is pushing water which needs lot of torque. Most escs aren't water proof but some are but all must be water cooled for use in boats .
Low speed and boat escs don't usually mix with brushless systems but then i don't run slow boats only fast, maybe someone else can comment on that bit . You can programme most to a soft start which would help,yes you can get sensored water cooled escs .

[Leaky Bottom]

You can use your 2 s lipos just wire them up to produce 4 s and your good to go,actually as far as load goes boats are under way more than cars as the prop is pushing water which needs lot of torque. Most escs aren't water proof but some are but all must be water cooled for use in boats .
Low speed and boat escs don't usually mix with brushless systems but then i don't run slow boats only fast, maybe someone else can comment on that bit . You can programme most to a soft start which would help,yes you can get sensored water cooled escs .

I think saying all esc's must be watercooled isn't correct, I use standard aircraft esc's in my sports boats and none of them are watercooled yet they all work fine, if you've got a high powered large fast boat then you may well be correct in what your saying but as the OP's boat would appear to be your average sport boat then I personally wouldn't go to the trouble and expense of buying a watercooled esc

[martno1fan]

Water cooled escs arent expensive and in boats it makes more sense than not to have it water cooled average sports boat or not.

[Leaky Bottom]

and the reasons why it makes more sense are!!!?

[martno1fan]

and the reasons why it makes more sense are!!!?

I wont even bother answering that one as the answer is pretty obvious,now go troll somewhere else.

[IanLloyd]

Heah come on guys!


I have run lots of boats both with watercooled and non watercooled speedos. Only the faster ones really needed the cooling although pretty much all my boats I have used watercooled motors just because I can.


My other Sportsman which runs twin motors and is quite quick really needed the watercooled speedos as a fair amount of heat is generated. The single shaft one is much slower and really does not get very warm so no need for watercooling.


They both are good in their own way although I suspect water cooling is beneficial in faster boats and not in others, otherwise people like Mtroniks would not sell so many speedos.

[Leaky Bottom]

The answer is not pretty obvious, your telling people who have asked a genuine question that you "must water cool all esc's" without giving a reason to do so.
If that is what you do with your models then that's fine, I don't  and the reason is they work perfectly OK without.

If you cant give a sensible and informed answer other then accusing some one of trolling then it perhaps would be best not to bother replying.

[unbuiltnautilus]

I would agree that a model that needs up to 22.2v of power to get it to go, should really REALLY be water cooled. The idea that a brushless set up running at UP TO 11.1v needs the same is wrong. We are dealing with a sport scale set up, not a balls to the wall racing set up. With the correct choice of speed control, i.e. don't skimp, don't be a tight wad, and the correct choice of motor and prop, performance should be achieved without excessive current drain. If you can keep the current below, say 15 amps, and the speed control is big enough to handle this, say 30 to 40 amps, why pump water through your electrics?
In my many, many years (!) dealing with all manner of speed controls, I have seen too many water cooled speed controls blow a seal and flood out the electronics, not for me. My current set up is running an Mtroniks Hydra 50, which has a big heat sink built in. The highest current I have managed so far was with a 1250Kv motor at 8.4v, 17 Amps. Running for fifteen minutes in the water, the unit was stone cold.
I am late to the party with brushless, and listening to advice from everyone and their dog, I realised the only way to see the way forward, was to get stuck in, and record the results.
A large number of brushless set ups early on, seemed to use aircraft configurations, high voltages, up to 6s, and high RPM motors, the whole lot then being 'managed' back to a sensible speed, via either a programming card, or via the Tx end point set ups. Why not just fit the right motor for the job instead? This is what I am trying out and I stand by the suggestions above as being suitable for a 33" by about 11", fairly high CG model.

[U-33]

Lesro Sportsman...my first ever boat, built back in the seventies. Had an Enya .19 ic motor if I remember correctly, and named 'Crystal Voyager'...

[martno1fan]

I ran my old 32" pt boat using the 540 motors and a car esc it always ran hot so i have and will always use water cooling on an esc and ive never had an issue with anything leaking , true i mainly run fast boats nowadays but i see no reason why id go back to using non cooled esc,s on anything with any kind of decent speed .
I do agree about the kv of the motor been right for the job and did try to link a motor but put the wrong link up doh,ill try again later .

[unbuiltnautilus]

We are doubly lucky now to have both brushless motors and LiPo batteries to use in our fast models. Ten years ago and beyond, the only option to drive fast models was 540 type motors, with or without gearboxes. Direct drive was always the best option, but with the penalty of very high temperatures and very short run times.
I believe that up until recently, most brushless conversions or fit outs have resulted in over powered models. It is in no small part down to the work of the large scale lifeboat modellers and forums such as these, that suitable sport scale set ups are being used effectively, and the details spread out to modellers in general.
Long may it continue

[U-33]

Well said, that man!

[Ron Rees]

With quite a few years experience of using all types of power sources in model boats I have a collection of brushed motor powered models which I have currently left the same.
 I am now, however a proponent of fitting brushless motors to new models as I design and make them. These motors are very well made, highly efficient, quieter and cooler when not pushed beyond the limit. They are good value generally costing marginally more as they get more popular and if you search for the right ones.


Going back to Ians original question...the Lesro Sportsman was and still is a fairly beamy model with nice lines that performs nicely, in other words, it goes!! but it's not 'scintillating.... with the original 540 set-up as recommended by Les Rowel. If he had had access to brushless at that time he would have definately fitted one I am sure. An upgrade will transform this model, but they were quite heavy because of the plywood and the methods of building them used by Les at that time.


Your model is doubtless fitted with its original 540 sized mount and a brushless motor of 35mm diameter will fit that mount with very little fettling. A 35mm brushless motor is, however, much more powerful than the 540. I would still fit one and maybe look for a 3540 or thereabouts with Kv rating of between 500 and 1000  (500 to 1000 revolutions per volt) Your 7.4 v Li-Po's are perfectly suitable but I would use 2 of them in that hull, doubling the Amperage per hours and keeping the voltage the same.


There are some fantastic Waterproof speed controllers out there now and I use the Alexander Engel Sub-Commander 30 amp units which cost about 28 Euros from Germany (£25. or so) They are 100% forward and 50% reverse as standard. They are fitted with Water cooling if you wish to use it, I have never needed to use this facility yet, so would recommend trying out the setup without the water and if its gets a bit warm, then retro fit the water scoops etc.
Hobbyking do an identical Esc ( Pt. No. 74071....9020000031-0) which is a little cheaper. Their own chunkier Waterproof Escapes start with the 30 Amp which would suit this motor,  then 50 and 80 and 120, but I don't think you'll need them, They do like to be connected to the water for long ( 20 minute runs at full power) but are good value.


I would start with a 'K' series 35mm racing nylon 2 bladed Graupner prop from Gliders UK and play with sizes until you get the best results, but not much bigger than a 40. These motors need to reach optimum speed to run efficiently and therefore cooler.


Going brushless is a worthwhile upgrade on a model like this and will give it a new lease of life. Go for it.


Hope this helps.....Happy New Year and happy boating.


Ron Rees.

[IanLloyd]

Some great advice thank you. Certainly will be changing to brushless when I get to that point and now have the infirmation to decide what I will need.


Thank you all.

[canabus]

Hi Ian
A few years ago my wife brought me a Off Shore Racer (850mm) for Christmas with a geared 540 motor or Nicads.

The speed control die, so I replaced to whole guts.

3639-1100kv brushless motor, 100 Amp car ESC, 5800mah 3S Lipo Battery but still used the 40mm 2 blade prop.

Great increase in speed and run time.

Ran this setup for above six months and upgraded the battery to 4S 5800mah.

Next up grade was the motor to a 3648-1450kv(straight change over).

Finally change the prop to alloy 2 blade 40mm.
All parts from Hobbyking.