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[JimG]

The good old method of bedding in the brushes on a brushed motor. Used to do this all of the time with motors for fast electrics (540 type buggy motors), stick them in a glass of water, connect to a 7.2V NiCd then stop when the water started to get blackened. This method kept the motor cool while washing the carbon off of the commutator as the brushes bedded in. Once ready just dry the motor off, put some oil on the bearings (bronze bushes) and fit to the boat. No longer needed with brushless motors and less need with scale type brushed motors as the current is much lower and less likely to get sparking at the brushes.
Jim

[Simmerit]

Best idea is to do a bit of homework. A similar issue just been discussed on the Model Boats website with links.

https://www.modelboats.co.uk/forums/postings.asp?th=183855&p=1

Otherwise you risk taking advice you don't fully understand which is not a recipe for success. That said, any advice from RAFLaunches on here is well worth listening to but, as always, there are several ways of skinning the proverbial cat.

The two shafts on each side will always be operated together so there is a good case for linking them and using one motor on each side which simplifies the wiring, speed controllers etc. and saves space.

You need to get a handle on all this BEFORE you start building. All those nice expensive fittings are essentially the icing on the cake but you have to bake the cake first!

Colin

Many thanks - will take a look.

[Simmerit]

Ok so this just got a bit harder.  Having read up a bit to it, it would appear I could go for four brushless motors and programme them so that if I'm turning to port, the starboard motors can go into reverse whilst the port motors carry on forwards, so you are using engine control to make the manoeuvre.  Have I got that right?


The other thing is R/C - seems to have come on a bit since my old man bought me a two channel 27Mhz Sanwa II R/C unit.  I think I need individual channels for each motor, and each channel can be programmed.  So if I put smoke in and have the guns turning, I'm looking at about 8 channel radio.


So do I go down the brushless route, and what is an equivalent motor to the 550 recommended by the lad who built Invincible and Dreadnought, and what do I do about speed controllers?  And which R/C transmitter and receiver do I go for????


Has this all of a sudden become bloody complex, or am I overcomplicating it?

[Dan]

The electrical side of it can be daunting and it can be very easy to over think/over complicate things. I know because I’m guilty of it.
Something to think about is how you want it to look on the water. Personally I like my warship to look like it has a nice scale speed and realistic turning circle. So if it was me, I wouldn’t worry about having motors moving in opposite directions during a turn, as long as you have a good throw in each direction on your rudder you should be fine. From that you could run two of the four motors off one ESC and the other two motors off a second ESC connected with a Y lead to the channel in your receiver. (I think you’d be pushing even a 40amp esc if you were running all 4 motors off one ESC) So you’d have 4 motors, two ESCs and these could be run from one channel on your transmitter. Be careful if your ESCs have a built in BEC. You don’t want two BECs connected to your receiver. This can be sorted but you’ll just need to check the ESC instructions.


Motor wise, from my experience I’d suggest a 500 brushed motor. My warship which is about 5ft long has two 380 size motors and this gives a lovely scale speed at 1/2 throttle, but I have more should I need to get out of the way of anything. I believe your dreadnought is a similar length but wider. So I don’t think you’d need bigger than 500 motors, especially if you have 4 of them 


I can’t answer about brushless because I don’t use them in boats.


Radio gear depends on your budget. Personally I like the Spektrum dx9. Plenty of channels and a lot of them are programmable. For example you can adjust your throttle,  so if you have a lot of power at the top end of your throttle and your scale warship looks more like a speed boat crossing the pond you can adjust the throttle curve and give yourself only 50% at full throttle. Obviously there are many others out there to suit your budget and needs, but the more working features you want, the more channels you’ll want on your transmitter.
 I hope that makes some sort of sense and helps a bit.

[Simmerit]

The electrical side of it can be daunting and it can be very easy to over think/over complicate things. I know because I’m guilty of it.
Something to think about is how you want it to look on the water. Personally I like my warship to look like it has a nice scale speed and realistic turning circle. So if it was me, I wouldn’t worry about having motors moving in opposite directions during a turn, as long as you have a good throw in each direction on your rudder you should be fine. From that you could run two of the four motors off one ESC and the other two motors off a second ESC connected with a Y lead to the channel in your receiver. (I think you’d be pushing even a 40amp esc if you were running all 4 motors off one ESC) So you’d have 4 motors, two ESCs and these could be run from one channel on your transmitter. Be careful if your ESCs have a built in BEC. You don’t want two BECs connected to your receiver. This can be sorted but you’ll just need to check the ESC instructions.


Motor wise, from my experience I’d suggest a 500 brushed motor. My warship which is about 5ft long has two 380 size motors and this gives a lovely scale speed at 1/2 throttle, but I have more should I need to get out of the way of anything. I believe your dreadnought is a similar length but wider. So I don’t think you’d need bigger than 500 motors, especially if you have 4 of them 


I can’t answer about brushless because I don’t use them in boats.


Radio gear depends on your budget. Personally I like the Spektrum dx9. Plenty of channels and a lot of them are programmable. For example you can adjust your throttle,  so if you have a lot of power at the top end of your throttle and your scale warship looks more like a speed boat crossing the pond you can adjust the throttle curve and give yourself only 50% at full throttle. Obviously there are many others out there to suit your budget and needs, but the more working features you want, the more channels you’ll want on your transmitter.
 I hope that makes some sort of sense and helps a bit.

Thank you - that is really helpful.  Now about these BECs.  What exactly do they do and do you buy them with the radio kit?

[Ralph]

BEC means battery eliminator circuit, basically it does away with the need for a separate battery for the receiver by powering the radio from your drive battery through the ESC, reducing the voltage to a suitable level - most modern ESCs have this built in as standard so no need to buy anything extra, just check the spec for your chosen ESCs.


If you have two BEC ESCs connected to one receiver then as a general rule the positive lead on one ESC needs to be disconnected, simplest way to do this is lift the wee tab on the plug with a craft knife and slide out the pin on the red lead, tape it back so it's out of the way but available if you ever want to use the ESC elsewhere.  As Dan said, just check the instructions.


Hope this helps and good luck with the build


Ralph

[Dan]

Sometimes you'll see receivers in a model and they will have a small battery pack plugged into them directly. This powers the receiver and servos.
If you don't use a separate battery pack to power the Rx and servos, you need a BEC. The BEC basically takes a safe voltage from your main battery and uses that to power the RX and servos. I know alot of ESC's have built in BEC's.


 When you use two ESCs together with built in BECs, usually you simply remove one of the 3 wires from the RX plug. Which colour you remove will depend on the make of ESC. But obviously you need to check this when the time comes.


I use mtroniks ESCs and they have a built in BEC. So I don't use the separate smaller battery pack.

[Bunkerbarge]

If you get a copy of Model Boats Magazine, June 2022, there is an explanation, with clear diagrams, of the various possible options for controlling two shafts, which can equally be applied to four.

[Geoff]

I'm often surprised at how much power some models seem to use. Reference on this one to a 40amp speed controller really surprised me. My Iron Duke is 78 inches long and about 60 pounds in weight and gets to scale speed easily yet only draws about 3.5 amps in all.


Its powered by two car blower motors (old Talbot Horizon) they are 12 poll 12/14 volt motors with silent running and enormous torque. I run them in parallel on 6 volts and as above max current draw is about 3.5 amps in all.


Direct drive on the inner motors and "O" ring drive to the outer shafts. In 6 years sailing I've never experienced an "O" ring break. ID has twin rudders which are in line with the two inner shafts so manoeuvrability is fine.


I use one Electronize speed controller to power both motors together and have never had any problems. I have a 10 amp fuse between the battery and the speed controller and separate 5 amp fuses to each motor for protection and this works fine.


Unless weight is a concern I never use BEC because if the main battery voltage drops too much it all shuts down. Much better to have a separate supply to the receiver to avoid this issue IMHO.


Batteries in ID are lead acid/gell so I can virtually run them flat and creep back but if linked to a BEC it would just die and stop.


I look forward to your progress


Cheers


Geoff

[Colin Bishop]

I agree with Geoff 100%. I can't understand  how some boats seem to generate huge power consumption figures, it just suggests that the  drive setup is wrong. I've always been an advocate of gearing down the motor at 2:1 or 2.5:1 using pulley drive which helps both the motor and the propeller to achieve optimum output. A common fault is to overload the motor by using direct drive to a prop which is too large for it which introduces inefficiencies in both. My 48 inch Fishery Cruiser is quite a heavy model but draws no more than 2.5 amps at full speed on both props. A 10 amp ESC is overkill, let alone a 40 amp one!

For efficiency, motors need to run at a high speed but props need much lower revs. Whilst a rule of thumb for brushed motors is that the prop should not be bigger than the diameter of the motor casing you can still get big improvements in consumption by gearing the prop down. Very few people seem to appreciate this.

Very often there are questions about cooling the motor down by introducing water cooling but unless you are trying for speed records this is simply a symptom of a mismatched driveline and you are just turning wasted effort into heat. An efficient setup in a scale model will always run cool.

Colin

[Tworrs]

I've been waiting for the resup and it has arrived all the way from sunny New Zealand.  I'm a searchlight short (forgot to order)


I'm now just about ready to make a start on the build

If I may ask Simmerit, where in New Zealand did you get the 3D printed parts?
Garry

[Dan]

Having Read Colin and Geoffs replies I’ll say I’m only going on experience with ESC sizes when I meantioned the 40amp. I’ve seen boats with two 550 motors running off one 30amp esc completely cook it. Not just once, a few times different, people, different models.
That said, I would follow Colin and Geoffs advice. Theirs has good facts and figures where as mine was just from what I’ve experienced. Apologies for the perhaps useless advice on the ESC size 

[Colin Bishop]

No intention of being critical Dan and it is always best to be safe rather than sorry with ESCs. It is just very common that many people don't appreciate the potential power consumption savings that come with getting the right driveline setup. The more the knowledge is shared, the more model builders will benefit.

Colin

[Dan]

Totally agree Colin. I'm always happy to be corrected/advised too. With most things I do tend to go up a big extra than what I need just to be safe. 

[Simmerit]

If I may ask Simmerit, where in New Zealand did you get the 3D printed parts?
Garry

Micro Master.  The kit is stunning.  The CAD drawings were done using Norman Ough's drawings - you can imagine the standard.


Prepare to lie down when you've looked at the prices and you will need a wet t-towel to put over your head.


Just saying

[Simmerit]

Thanks for the discussion on motors lads - looks like I need to get my maths head on as I need to do some sums.  I am 99.7% certain I'm going for 4 x brushless motors.  The plan is to work out what electrics I need, take a sharp intake of breath and order them this weekend + a smoke generator thingie and a sound thingie.


New 4mm ply came for the decks - I've got to recut them from the originals shipped with the kit as they are banana shaped


Mrs spotted the customs bill for importing the New Zealand manufactured bits and bobs.  FORTUNATELY I bought her a git big leather hippo from Selfridges for her birthday so I didn't get any grief, and she's just landed the Lego Titanic for Chrimbo.  I'm being told I cant have any more guns, but I've got to work out how to get a Lee-Enfield 4T L42A1 through the door .  In the meantime this came today and she answered the door to it so I thought I was in trouble.  Its not been mentioned yet......

[Tworrs]

Micro Master.  The kit is stunning.  The CAD drawings were done using Norman Ough's drawings - you can imagine the standard.


Prepare to lie down when you've looked at the prices and you will need a wet t-towel to put over your head.


Just saying

Thanks for the info, I'll have a tentative look at their offerings, after taking my medication.

[Simmerit]

I'm often surprised at how much power some models seem to use. Reference on this one to a 40amp speed controller really surprised me. My Iron Duke is 78 inches long and about 60 pounds in weight and gets to scale speed easily yet only draws about 3.5 amps in all.


Its powered by two car blower motors (old Talbot Horizon) they are 12 poll 12/14 volt motors with silent running and enormous torque. I run them in parallel on 6 volts and as above max current draw is about 3.5 amps in all.


Direct drive on the inner motors and "O" ring drive to the outer shafts. In 6 years sailing I've never experienced an "O" ring break. ID has twin rudders which are in line with the two inner shafts so manoeuvrability is fine.


I use one Electronize speed controller to power both motors together and have never had any problems. I have a 10 amp fuse between the battery and the speed controller and separate 5 amp fuses to each motor for protection and this works fine.


Unless weight is a concern I never use BEC because if the main battery voltage drops too much it all shuts down. Much better to have a separate supply to the receiver to avoid this issue IMHO.


Batteries in ID are lead acid/gell so I can virtually run them flat and creep back but if linked to a BEC it would just die and stop.


I look forward to your progress


Cheers


Geoff

Thanks Geoff,


quick question or two if I may?


What Speed Controllers do you use and do you run your receiver and servos off normal batteries (duracell AAs or some such like)?


Cheers


Si

[Colin Bishop]

Geoff is using brushed motors and associated speed controllers which is a quite different setup from what you would need if you use brushless motors which require their own individual controllers.

As he explains above, his arrangement is a very effective way of propelling a model of this type and only needs two speed controllers. Much simpler all round.

Colin

[Simmerit]

Geoff is using brushed motors and associated speed controllers which is a quite different setup from what you would need if you use brushless motors which require their own individual controllers.

As he explains above, his arrangement is a very effective way of propelling a model of this type and only needs two speed controllers. Much simpler all round.

Colin

Yep I'd clocked that.  I'm still looking at both options - hence the questions, but fairly certain I'm going brushless (I think)....!

[Geoff]

Hi, I actually use a single speed controller to control both motors. Elecronize which are no longer available which is a real shame.


i am using brushed motors which for battleship applications are very economical in terms of power consumption and cost. I'm happy to be corrected but think brushless are too expensive when combined with their speed controllers and my perceptions are generly more suitable to light weight fast models where power and weight are key.


For the reciever I use a sepearate 6v lead acid/gell battery so there is little chance of running out of power.


Motor choice for battleship models can be difficult as what we want are high torque slow reving motors. In practice we don't need that much manouverability as the real ships didn't. In my general opinion its always best to keep it simple for reliabilty.


cheers


Geoff

[Backerther]

 I do think so with Geoff's opinion if the battleship is intended to sail really on the water for "regular service", not as a merely ceremonial maiden voyage. Reliability, safety, stability and easy maintenance are to be more focused on when operating the model ship regularly on the water for happy boating and boaters. The nature is frequently so severe to the model ships /boats on the water, just like a RC airplane in the sky.
If I were you, I would definitely use brushed motors which I think are sufficient and adequate for the slow sailing scale model especially like the large battleship. !! 

1; Simple!   
2; while reliable on the water! 
 

[Simmerit]

OK.  I thinkI've got the message......





Brushed motors are the way to go!

[Simmerit]

Right then.  I've just ordered 4 x 550 motors.  Next one is batteries.  RAFLaunches said he runs his with 3 x sealed lead acid batteries.  I've lost the will to live with sums on power consumption so can someone do me a favoUR and spell out in words of one syllable what I need?  Its a mystery to me I'm afraid.


I found these lads that do them


https://howesmodels.co.uk/product-category/batteries-chargers/lead-acid-batteries-and-chargers/12-volt-lead-acid/

and what do I do about a charger?

I take it two of these will do as well?

https://howesmodels.co.uk/product/mtroniks-viper-marine-40-boat-esc-electric-speed-controller/

[Colin Bishop]

Without wishing to rain on your parade, you need to calculate how much weight you can devote to the batteries (and therefore their capacity) bearing in mind the likely weight of the rest of the model. Idealy you need to be in a situation where you still need some ballast to bring the model down to its correct waterline. Lead acid batteries come in all shapes, sizes, weigts and capacities and will need to fit under the deck as low down as possible to maximise stability.You can lay them down flat but the 'top end' is usually lighter than the bottom which can affect weight distribution.

You have taken on a major project even for experienced modellers and words of one syllable don't really cut it I'm afraid. If you can find someone who has already built this model successfully then unless you are prepared to do a lot of research then it is best to replicate that setup in the knowledge that it works. It will save you a lot of grief.

As for moving the turrets and guns, that is a whole different ball game and there are lots of posts on here which discuss it as there are many possible options. This thread showw what the possibilities are:

https://www.modelboatmayhem.co.uk/forum/index.php/topic,56800.0.html

Colin