Print

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

[bigbloke]

Hi folks,

first post here on these forums.

I have been away from rc modelling for must be ..ewwww.....28 years now?!

My return was prompted, to my acute surprise, by my 6 year old daughter writing to santa
asking for 2 radio controlled boats "for her and daddy to sail together" ;-)

Well with the strict management of my pragmatic missus, santa went onto ebay and ordered a
20" cabin cruiser type boat (wifey didnt think Daughter would really want to sail her own boat
all the time and didnt want 2 boats cluttering up the house).

When santa delivered our present though, it was a different boat entirely , considerably bigger in
fact than we expected! It was one of these:



costing at least 25% more. We contacted the seller, but never received a reply, Sadly nor did
we get a response from Santa, "on leave till November" apparently

Fortunately Daughter was delighted by this boat, Dad was fairly happy too ;-)

I duly charged up the 7.2v 1.8Ah battery and off we went to the local boating lake.
For the first few minutes the boat went great, but very quickly it was obvious that
the battery was underrated. By the third outing, the battery was clearly stuffed, it
lasted only a few minutes.

As a techie by profession & nature, I went online and sought 2 new battery packs,
I found a matching NiMH one, right size, right voltage, right tamiya connectors, great
price, and around 3.7AH capacity. (componentshop.co.uk) I hummed and hahed about fitting
a current limiter but thought we'd try it "as was" and see how we got on

Having all the right chargers allready (through my numberous tech hobby activites) I ditched
the original battery, and charged up the new ones . And on Sunday we went off to a local pond.

What an improvement! the boat was fast enough to be fun for me without being too fast for daughter to handle.
and was still going stronger than the original battery some 25 minutes later....that was .....until the port motor
went up in smoke, completely overheated despite the enlarged heatsink I fitted to it prior to its first "uprated"
outing

So ...I'm looking for a new pair of 380 motors!

If they go a "little faster" again then we would both be delighted but ideally they need to run off this 7.2V 3.7Ah race
pack without getting too hot, although I can easilly add water cooling into the base of the boat and wrap some copper
tube around the motor body.

I can also probably accomodate a larger heatsink again too , even possibly to consider fitting one on the top of the boat out in the
open air so its cooled as it moves.

So ..since I have no idea of the current marketplace, what motors do you folk suggest I shoud buy ? and why please ?

I suppose at this point I should mention that the boat is twin propped direct drive with brass transmission rods,
props are plastic,twin bladed  around 1" diamater max, labelled DX and SX respectively. steering is cheap and cheerfull
i,e, turning off one of the motors at a time respectively.

Also gratefull for any useful Uk places to buy from - all the local model shops appear to have closed <sigh>.

Many thanks in advance

Regards


BB





 

[BobF]

Hi bigbloke,

The first thing to watch out for will be burning out the speed controller, which I believe will be all contained within the receiver box.

The route I would go, but it depends on funds available. Would be to scrap all the electric workings and fit a normal radio control, plus a  propper speed controll and a mixer. Thus still controlling the motors for turning, but having speed controll as well. I can't give any more technical details as I have not yet gone this route myself. But an electronic speed controller  approx 20 pounds  upwards and a mixer 25 pounds upwards.
I have just bought a second hand twin prop boat off Ebay intending to do the above mod. But the previous owner has already started to convert it to single shaft so I will finish the job with a normal rudder. No doubt at some time in the not too distant future I will get one similar to yours, and give that a go.

Bob

[Bridkid]

Hi BB.

One thing you must watch out for is the fact that one motor cuts out to make the boat turn. If you continually turn the same way then one motor will take much more 'hammer' than the other one possibly leading to overheating. Might I suugest 2 matching 480 motors, namely HLN 480's. They cost about £8 each and are the same diameter cans as 380's and 400's but just a tad longer. IMHO they are better than the 380/400's but if you can't find these then 2 X 6 volt 400's should do quite nicely, they cost around the same as the 480's. True what Bob says, the best bet is to strip it out and put 'standard' radio gear in it including an electronic speed control at the same time.
Having said all that there are a couple of MFA 380 3-pole motors on this page that might be worth a try!

http://www.pandanmodelboats.co.uk/acatalog/Our_Online_Catalogue_Electric_Motors_and_Connectors_etc_247.html 
(6th photo down the page)

Have fun,
Ian
 

[Fast Electricals]

There are plenty of 400 (380 size) motors around at reasonable prices. The MIG 400 from Astec ( http://www.astecmodels.co.uk ) is good value and just as powerful as the big name brands, as is the Electramax 400 from Overlander ( http://www.overlander.co.uk ). A 7.2v motor will be a bit slower and will run cooler than a 6v motor on 7.2v but will be easier on the control equipment. Judging by the run time on the 3.7Ah pack, the motors sound like standard 400s.

Neil   

[denboy01]

Search for Twin-480BB-Motors-Replace-your-380s-Get-the-Video-Mega on ebay
worth a look

[bigbloke]

Hi Folks,

Thanks for the feedback , genuinely appreciated .

BobF  -  Yes I fully appreciate that it would be best to do that, and whilst funds are available, I think I'd better wait and see whether
 or not this is a "temporary fancy" for my Daughter or whether she wants to stick with it a bit. I sold all my Futaba kit in my teens to fund
other hobbies. My son just turned 1 last month so whilst there could be a second generation of boating to go on, theres a few years of
catch up to take place. As for me, well, two kids plus running my own Tech Consultancy business largely keeps me away from hobbies
that I can involve myself in whilst the kids are awake! ;-)

I must admit though , I keep looking at plans for a hydrofoam...... ;-)

Bridkid,Fast Electricals, denboy01  -  great reccomendations ! thanks chaps ! I'll have a good old trawl and see over the next few days
I think my best way forward is to spend a little replacing the motors, and have a look at the control circuitry and add some current limiting in there as a
cheap temporary measure (not afraid to design electronics / wield a soldering iron)

One question though - is there somewhere I can read up on interpreting the dimensions of motors, as for example I have interpreted
through your responses that a 380, 400 and maybe even a 480 motor may be interchangable  - how do I work out which "category"
equates to which body size and spindle dimensions please ?

MTIA

Regards

Rob (BB)   

[cbr900]

Bigbloke,

I have already made the same changes to two types of fleabay boats and the shafts are all the same size, no problems there, as for the electronics they are crap if you can change them, you will be a lot better off..



Roy

[BobF]

Hi Bigbloke

400 series motors have a 2.3 mm dia shaft
480 series motors have a 3.17mm dia shaft

The dia of the can is also larger as are the fixing centers if using the end plate holes.

There would not be much point in using 480 motors, and then fitting an amp limiter.

Bob

[Bridkid]

Bob.

The 400 series do indeed have a shaft of 2.3mm but if you use the HLN 480's they have the same size shaft, just a longer can, unlike the Graupner 480's which are 3.17mm shafts and more 'chunky'.

400/380's and HLN 480's are fully interchangeable. (HLN 480's are far less greedy on the amps than Graupner's too) I used to buy my HLN's from an Ebay seller called Biggles Skyman at about £6 each. Not sure if he still sells them now though.
Cheers,
Ian.