Model Boat Mayhem
The Shipyard ( Dry Dock ): Builds & Questions => Pleasure boats, Sports, Race, Power and Leisure Boats: => Topic started by: Degsamillion on December 28, 2013, 11:28:02 pm
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Hi, I have an RAF crash tender (36") and am currently running a 543-23 electronize low drain motor with a 12v 14a lead acid battery (a bit heavy really!) run via a 20a viper marine mtroniks ESC - I'd like to get it to 'plane' and have been advised to try a 500 motor with a 7.2v battery pack. Can anyone give advice please? What sort of 500 motor will work with my ESC, and will the 20a ESC work with a 7.2v battery pack (say 3000mah)?
PS I need a motor with a 3.2mm shaft..
Thanks!
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The inability to plane may well be due to the heavy battery, although as far as I know, the motor you mention is relatively low revving which may also have an effect. The ESC will work with any battery (other than Li-Po) within its voltage range, the critical factor is the current draw. Those with more technical know-how should be able to help you further.
Peter.
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Splendid, thank you peter. Any idea how I work out the current draw?
Thanks again..
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Personall I wouldnt bother with a 500 still to small to get it to plane far better off with a 700 series .As regards needing a shaft of 3.2mm you can allways get a huco brass coupling to fit....what size is the prop and what diameter is it.You can of course run a 900 series motor and 55mm prop on it that defo would get it to plane especially on 14v BUT you will need a new speed controller as the viper will only support 12v. As for current draw i can tell you straight that combinatiobn on the 900 would draw around 10amps max.A700 series would probably draw around 15plus amps.
Dave
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I run my Raf Fire Tender 36" on a Graupner 600 8.4vMotor with Nimh battery pack.
with a Viper Mtroniks 20a Esc. It planes perfectly.
I have also refurbished another and used a Graupner 600 7.2v which actually revs slightly
higher - it also ran very well.
Both motors available with 3.17mm dia shafts provided you can still find a motor -they
are hard to get at the moment due to manufacturer problems.
Two blade prop about 35-37 dia.is fine.
N
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Fantastic help guys, many thanks! What a great forum!
Ok, I've located a 600 7.2v (600 8.4v out of stock as you said Nordlys!) but the props I have are 45mm, a three blade brass or a two blade plastic. Will they work ok?
Thanks again..
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You won't need the 3 blade prop for this boat. The motor will run cooler on your 2 blade prop normally, although I did have to put a water cooling coil around my motor - which is quite straightforward apart from a bit of fixing of the water scoop -but you may not need to do this.
That prop you have at 45mm will probably be too large -stick to something under 40mm.
You will be surprised that a smaller prop will move the boat just as fast and leave the motor much cooler.
Best thing is to experiment down at the water with various sizes of prop -you will see the results much clearer.
600 7.2v is a good motor to use - good high rpm - you don't have to run her at full speed.
Battery is also a bit lighter.
N.....
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A 45mm 2 blade prop would require the power of a 700 BB turbo motor.
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I've just bought a boat same as yours. Came with a 6v SLA with a Johnson 600 motor. It wouldn't get up on the plane, but did go a reasonable speed. The battery was almost at the front of the boat, no wonder it didn't plane!
I have now changed the battery to my 7.2v NiMH and it's temorarily located in the rear open air bit. The boat goes a better speed and is very close to planing! I keep intending to try it on 12v to see what it can do...
Anyway, heres a video of it the other week, on a 7.2v pack:
http://www.youtube.com/watch?v=XfC0WEkGpC0&feature=c4-overview&list=UU1zLURxYyxPr6c275R1ynwA (http://www.youtube.com/watch?v=XfC0WEkGpC0&feature=c4-overview&list=UU1zLURxYyxPr6c275R1ynwA)
Speed controller is just a Viper marine 15, seems to work well enough!
I doubt that a 500 motor would be beefy enough to make it plane, these are heavy boats, but getting the battery in the right place will help a lot!
Hope this helps,
Steven.
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I have positioned the battery in my boat in the next compartment up from the rudder compartment - 20cms from the transom, laying across the width of the boat.
It will make quite a difference where you site the battery as regards planing.
I have seen 46" Fire Tenders running on 12v lead acid batteries but not our 34" size.
I would rather use a 20amp Esc tho', they aren't that much more expensive and provide that bit of spare rating should your boat draw a bit more current.
Your boat does look good Steve!
N......
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Thanks fellow crash tender users - fabulous help! I've located the bits I need online now - next question, a charger for the new 7.2v Nimh battery - I've got a radio shack charger ref 23-7110 that says it will charge a 7.2/9.6v battery, but says it's only for Ni-cad batteries - will it charge the 7.2v nimh one ok?
Best,
Eric
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I can't seem to find any info on your charger, but I use this for my 7.2v NiMH:
http://www.howesmodels.co.uk/product/Universal%20Smart%20Charger
Works well enough for me, does NiCDs aswell as NiMH.
Cheers
Steven
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My charger is a Fusion NX85 and it says for Ni-cd & Ni-Mh batteries on it - so your
charger would seem to be ok as I see it.
N...
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personally, being the owner of a 3 foot and 4 foot version of this boat, I thought stavros had nailed it with a 700 size, like a 700bb turbo, but remember that motor/esc and battery is not the full story, the prop is important, as suggested start small and work up, they are very inexpensive, also this hull must have effective spray rails running the length of the hull and up at the bow, or it will not plane, and will handle pretty poor, particularly in turns. There used to be a specific aerokits fireboat website, it now covers more general boats, but there is a section which has fireboat set ups, with video evidence of how they run, this might help :-))
(this is really in the wrong section, you will probably get more response in warships or general, ask a mod to move it)
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Just reading your reply there, red181. It got me thinking about my boat. As I bought it off eBay as a completed model, I had no input on the build. I did however notice the spray rails are fairly large, and very effective, I didn't realise they would have such an effect on making the boat plane and cornering.
Learn something new everyday I suppose!
Cheers,
Steven
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Hi Steven,
I learnt the hard way, my 3 footer due to various rebuilds when I didnt know any better rolls real bad on turns, An experienced friend nailed it right away as the spray rails have rounded and worn quite small. On the four footer I fitted new square profile and it turns superb. On another friends 3 footer in summer his would not plane at all with twin brushless, it had no rails, I fitted some and it transformed the handling and planing :-))
always learning when minds come together like here!