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[osman123]

Hiya folks,
My wife, bless her, has bought me a Mantua Bruma Yacht for my birthday which I have duly started to build with no problems up to now. However, I've seen that a special motor kit specific to this kit is available, but to my mind it seems extraordinary expensive for what it is. The kit basically consists of a single motor with a few gears so that two props can be used, plus one or two other items.......Price £45 incl Vat........As I said "expensive" for what it is especially as it doesn't even include an ESC!
I heard tale that whilst this kit is effective, it only runs at 6 volts and because of the way it's geared it's very noisy and fairly slow. With this in mind, I think I'd like to fit 2 separate motors with a single ESC which I think would be more cost effective. However, I not really electrically minded and am a little unsure as to what exact motors and ESC I should opt for. I'm guessing something along the lines of a pair of MFA RE-385 5-Pole DC Motors would suit my needs, along with a 15-20amp ESC, but I'm open to suggestions. I'm hoping someone on here has done the same conversion, but I'm open to any advice. I'm also wondering what power supply I should use? I've plenty of 7.2v 3800milliamp Ni-Mh batteries, so this would probably be the best option, although I not averse to putting in a 12 sealed gel battery if this would give me better running times. .........Thanks in anticipation........Ade

[Martin (Admin)]

FYI....

Mantua Bruma
Scale 1:45 Length 860mm

[stallspeed]

Mind that reduction gears have a purpose.The props supplied with the kit may not suit direct coupled 385 motors and you would need to purchase couplings too.
If you find guess the ratio from the gear set illustration and choose the bore from the prop and motor shafts you can get brass hub and brass pinion gears at a snip from shgmodels(see the forum ad).There is a whole section on gears.

[bigH]

   Once again,, THE MAN TO SPEAK TO IS>>>>> WAIT FOR IT>>>>
FLJ aka Dave at   ACTION ELECTRONICS. 

bigH

[Klunk]

http://www.lutonmodelboat.co.uk/members_models/imagepages/image6.html

take a look at this link. I know Bob is a member on here, so he might just reply to this thread.

[andrewh]

Ade

Certainly FLJ has the answers and good ones too

With this in mind, I think I'd like to fit 2 separate motors with a single ESC which I think would be more cost effective. However, I not really electrically minded and am a little unsure as to what exact motors and ESC I should opt for. I'm guessing something along the lines of a pair of MFA RE-385 5-Pole DC Motors would suit my needs, along with a 15-20amp ESC, but I'm open to suggestions. I'm hoping someone on here has done the same conversion, but I'm open to any advice. I'm also wondering what power supply I should use? I've plenty of 7.2v 3800milliamp Ni-Mh batteries, so this would probably be the best option, although I not averse to putting in a 12 sealed gel battery if this would give me better running times. .........Thanks in anticipation........Ade

I don't like either the noise of gears or much more so, the cost of them
Your thinking on motors is good - 385s would be right on the nose, and economic and quiet.  At the risk of settin off my fellow mayhemmers on a favourite topic you would absolutely not need 15 to 20 amp ESC - two 385s probably take 2A each when running and the ESC should not be sized for stall - that is the job of the fuse!

andrew

[des321]

Hi,
I am also building the Bruma kit which I purchased from Cornwall Model Boats back in March. In a telcon with them they suggested I did not buy the motor pack as it was expensive for what it was. Also it turns both props in the same direction which does not give good manoeverability and steering control. I bought LH and RH 3 blade 35mm brass propellers and two 385 motors. Importantly I also fitted a mixer. On a test run when the hull and deck were completed she ran perfectly and will turn in her own length. I used 9.6 volt battery which was too fast. I think 7.2 will be quite adequate for achieving scale speed. If you don't fit a mixer you will have to control the motors independently with two channels, known as tank steering. If you want to know more about mixers speak to Action as has already been suggested in an earlier message.
I am in the final stages of fitting mine out. She should be complete within a week. Any more questions, don't hesitate to ask.

[andygh]

Insert Quote
http://www.lutonmodelboat.co.uk/members_models/imagepages/image6.html

take a look at this link. I know Bob is a member on here, so he might just reply to this thread.

Bob V's Bruma is very nice (and quiet ) There was a photo of it in MB a few months back

[osman123]

Excellent stuff guys, just what I wanted to know!

Des's post was extremely helpful as this is the way I'm more or less thinking of doing it. I'll probably keep the propshafts that are supplied with the kit as these seem quite substantial and well up to the job, unless of course anyone else knows any differently?
Would a mixer really be neccessary? Can I not just run the two motors straight from the ESC and if not, why not?........Sorry if that seems to be a dumb question, but this will be my first craft whereby I use two screws in the build. Also if I do need to buy a mixer, how much is that likely to cost, only I'm unfortunately disabled and as such live on benefits, so everything has to be done on a very tight budget, although I don't mind having to save for any bits that might be necessary.
I thought, like Des, that I would go with a couple of brass propellers, rayjer than the ones supplied with the kit as these seem to have been made with some kind of die-cast white metal and to be honest don't look that attractive. What would be the ideal size?......I'm thinking about 35mm, but any other advice would be very much gratefully received.
Thanks again for all the advice guys you're all such a knowledgable group of folk and whilst this might be my fifth build now, the amount of info I've gleaned from reading through all the forums is unmeasurable........
Best wishes to all.......Ade

[Bob_V]

Hi Osman123

Yes I have built the Bruma and have tried numerous motors, speed controllers and mixers.

I have always stuck to 280 size motors because of the limited space inside the hull.

At the moment I am using two Graupner Speed 280 motors with a single 10amp Mtronics Marine Micro Viper ESC run off a 6v NIMH pack.

I am currently experimenting with the mixing capability of my Turborix 2.4Ghz Tx which seems to be working very well in my 'Le Sphinx' which
is also a twin prop single rudder arrangement. I am about to fit this in my 'Bruma' with a second 10amp ESC and I am expecting very good results from that setup.

Will take a picture or two later.

Bob_V

[longshanks]

Hi Ade,

The Bruma is a nice looking boat - don't forget to post the odd pic during construction.

Reference motors the only thing I would note is that the 280 motors are turning at 14,000 + rpm and pulling 1.58amps.
The 385 9,280 rpm, .85 amps. So I would think you will get a longer sailing time.

You only need to use a mixer if you want maximum turning ability, very handy if you want to take on a scale steering course! You could always add a mixer later if you wanted to improve the turning circle.

Your Ni-Mh batteries will be perfectly adequate. I'm using the same batteries with 2 x 385 motors and get 45 mins plus - then change batteries.

Regards
longshanks

[osman123]

Aha.......That's what a mixer is for!  Simples...........

Right then decision has been made, I'm going to go for the 385 motors with a 15amp ESC, which incidently I have a spare one of, which is dead handy and saves me a few pennies. A mixer would be nice, but not something that's really necessary and as Longshanks say's, it's something I can always add at a later date if I decide I need that extra maneuverability.
I'm not too far into the build as yet, having only built the hull frame and deck, although I have planked the deck, having said all this the total build time so far is about 20 hours. Some might thing this is quite along time to get as far as I have, but I'm a stickler for getting the finish just right. I'm also limited to the actual amount of time I can stand there doing it. As I mentioned in my first post on this subject, I'm slightly disabled and suffer from chronic pain in my lower spine. This is because of an RTA I was involved in some 15 years ago whereby I actually broke my back, fortunately all the medical professionals managed to patch me up. So now I'm just walking wounded if you like, I was very lucky to say the least, but I do suffer terribly with pain now, but I live with it and it's managed fairly well with pain-killers.
I will post a few shots when I can find five minutes along with the rest of my 'fleet'  Which consists of a 42inch Huntsman, a plastic 1/20scale Police Boat which was given to me in terrible state, but which I've now restored. A 1/25 scale scratch-built Coal carrying Narrowboat. A 1/20 scale Osborn Models Miss America. With the exception of the Huntsman and now of course the Bruma. They're all smallish models, this is because I'm very limited for space and only have a 6x12 workshop in which to play, but I manage as best I can.
I'm not a member of any clubs other than this forum, but this is more to do with the fact I don't really like the cliques that you find in clubs of any description. But I can very often be found down at Portishead Lake which is my closest boating lake mucking about with my models, I also tinker about with some Nitro cars as well. My main hobby though is Photography, which I suppose you could say I'm a high end amateur specializing in wildlife and weddings, so if anyone want some really decent shots of your models on your wedding day, I'm your man to talk too   
Right then that's enough about me and that....When I get 5 spare minutes, I'll post some piccies up of how I'm getting on with this kit.
Thanks again for all your advice and support......Ade

[andygh]

I'm very limited for space and only have a 6x12 workshop in which to play, but I manage as best I can.

Ha, luxury, I wish I had that much space 

[Jeremy]

Hi Ade

July 23rd last year you posted the following message about your Bruma

I'm going to go for the 385 motors with a 15amp ESC, which incidently I have a spare one of, which is dead handy and saves me a few pennies. A mixer would be nice, but not something that's really necessary and as Longshanks say's, it's something I can always add at a later date if I decide I need that extra maneuverability.

I would be interested to know whether the build is complete and how the above arrangement worked.  I am about to start on a Bruma and face the same decisions.  Did you use just one ESC and, if so, how was it connected to the two motors?  Also, how did you ensure that the propellors rotated in opposite directions?  I know these are rather basic questions but I am fairly new to RC and Bruma will be my first twin screw boat. 

I would appreciate receiving the benefit of your experience .......

Jeremy