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[MikeA]

ok now im stuck. I want to use a surface peircing prop but im trying to decide which motor would be better.
either:
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=270793024308&ssPageName=STRK:MEWAX:IT

or

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=130560506212&ssPageName=STRK:MEWAX:IT

or

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=390261363448&ssPageName=STRK:MEWAX:IT

im making a 650mm boat mono hull

what do you all think? iny meny miny mo

[MikeA]

you know what forget that i went for the brushless. i know im gonna regret this

[Nige52]

No you're not.
You have bought a race tuned McLaren F1 compared to Steptoe's horse and a Ford 100E ........

[John Mk2]

Dead right there 

[MikeA]

well its 58mm by 34.5mm motor. ive looked at a lot of brushless boats and they all around the 2200kv range this is 3600 i hope its got enough torque. 58 by 34 seems like its a small motor and i dont know if the diameter includes the cooling jacket. it seems everyone measures there motors differently

[Nige52]

I have that exact same motor and ESC in an MFA Spearfish boat. I use an 11.1v 30c Lipo with it and it's mighty impressive on the water 

[MikeA]

i got 2 traxxas 8.4 3000mah batteries will they work with it or will i have problems?

[MikeA]

here is my hull i built today needs a bit more yet though:

[Nige52]

The only problem you'll have is that it'll be a little slow....I think you can go up to 18v with that motor?  That would be a 4 cell Lipo or a risky 5 cell 18.5v....Your batteries will power it, but I doubt it'll go much more than a little over scale speed.

[MikeA]

is that with my nimh itl be slow or with either lipos or nimh?

[Nige52]

Your batteries are 8.4v, regardless of what type they are, electric current is electric current. I run 11.1v and my Spearfish puts on a good show although it could go much faster with 14.8v and silly stupid at 18.5v...
You'll soon find out how your boat performs on it's initial trial.
 

[MikeA]

cant i join run them in series and get 16.8 or am is it going to starve the motor of amps?

[MikeA]

i am consdering useing lipo's but i know little about them. i need some help with them please.
1, if im to use lipo whats the best way to get 14.8 volt that will fit in my boat. should i run 2 saddle 7.4's or a single 4s battery.

2, i gather i need a low voltage cut off. usually with nimh if the batteries are gettin low the boat slows down and you know to bring it back in. But if lipos just cut off as before it slows down does that mean my boat is stuck out in the middle of the lake? what warning have i got?

3, wont 2 8.4's running 16.8 be faster than a 4s anyway? albeit heavier though

[Timo2]

Hi Mike

 You have a PM

Timo2

[MikeA]

you dont suppose u could possible fill in the blanks with the rest do you?

[CF-FZG]

i am consdering useing lipo's but i know little about them. i need some help with them please.
1, if im to use lipo whats the best way to get 14.8 volt that will fit in my boat. should i run 2 saddle 7.4's or a single 4s battery.

It depends on how much room you have - not a lot go with the 2 x 2S saddle packs in series or a single 4s, if you have plenty of room then you can also saddle up 2 x 4S in parallel for better duration.

2, i gather i need a low voltage cut off. usually with nimh if the batteries are gettin low the boat slows down and you know to bring it back in. But if lipos just cut off as before it slows down does that mean my boat is stuck out in the middle of the lake? what warning have i got?

Most esc's have the facility that when LVC cuts in you can reset the esc, (by going to low throttle), to allow 'main' power back, (at a reduced setting), to recover the model.

[/quote]3, wont 2 8.4's running 16.8 be faster than a 4s anyway? albeit heavier though

Hmmm, a fully charged 4S is at 16.8v and should hold a higher voltage, i.e. over 14.4v, under load better than the 14 cell NiMH pack, which will be starting at around 21v 'hot off the charger' stabilising at around 18-19v about 30 mins after charging, but will drop quicker than the LiPo under load.  ** comparing like for like capacity packs **


Mark.

[MikeA]

well my the limitations of the motor is 18v max. now with the consideration of funding im trying to run a surface drive with a solid prop shaft. this will mean that the motor is going to have to be as far forward as possible with propshaft running bang down the centre of the boat. I was thinking instead of using 1 large 4's battery use 2 2's batteries starddling the propshaft linked in series not parralell.

[CF-FZG]

Sounds like a good plan Mike

[MikeA]

you reckon? i was just looking on net to see if its safe to link lipos in series. i think if i can itl will make the boat more stable and keep cog low.

[nick_75au]

Li-Po is fine in series, they are fine in parallel as well, so long as they are the same capacity, "C" rating and make(ideally).

Cheers
Nick

[MikeA]

im looking at batteries right now. got to get a balance charger too all adding up

[Timo2]

Hi mike

    Have a look at   http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=11060

                          or

                           http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=6478


  Timo2

      4 of unit 1 , ,  2 of unit 2  in the local club

[MikeA]

what size prop shaft do ppl think i should use? i was thinking a 4mm dog drive theres a good supply or props for that size on giantcod. And other thing can i use a flex drive without the having the buy the expense of a stinger or strut?

[MikeA]

you know ive seen a lot of boats with the batteries one side how do they keep balanced?

[John Mk2]

To stop torque roll (Prop to big) & help self right if fitted a flood chamber is fitted.