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Batter plug size. Motor kv size. For 6s 8s 12s

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Batter plug size. Motor kv size. For 6s 8s 12s

Old 11-30-2019, 07:47 AM
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35bertram
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Default Batter plug size. Motor kv size. For 6s 8s 12s

hi. Thanks for any help
i have a number of boats.
Trying to work out how I want to wire the battery’s and esc. What plug I want to use and what kv to run on the 50” plus boats.

I run a 120a esc , 6s 8000mah 50c Lopo on 30” boats at 1800kv

my 40” boats all have 1450kv motors. I was going to run 6s 120a Esc but now am thinking they can take 8s
my 50” and larger boats I have not started rigging but was thinking a 56mm can turning around 1000kv mane 600kv idk yet.

I am debating on plug amp size. Is tx90 or a 90 plug large enough for 12s. What’s the larges cell size guys are running tx60 on?
Old 11-30-2019, 09:49 AM
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35bertram
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I’ll post photos but think I need to post 10 times first cuz I’m a new member.

I am rigging a 30”
king of shaves mono brushless
proboat black jack 29 brushless
out rigger 30 brushless
saducer 30 nitro
30” un known hull want to rig jet boat

i am rigging a 40”
prathner 40” brushless
m41 traxxas
prathner lapcat 36” with k&b 7.5 lower and 1450kv brushless
out rigger 40” nitro
shovel nose hydro

i am rigging a 50”
dumass scarab 50.—— Unrigged
dumass scarab 54. —- Un built
dumas 46” hydro atlas van line— unrigged
un known 50” mono rigged gas




Old 12-01-2019, 08:13 AM
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The TX90s will not be enough for most of your boats. They are rated at only 90 amps (not volts) so they don’t even match your ESC’s capability. If you want to use the same connectors for all your boats (a good idea btw) use at least the TX150s.

What are you expecting out of the 40”-50+” boats for speed and runtime? You will need more than 6S for them if you want much speed, most will run 8S to 10S averaging 150-200 amps....or more. Motor Kv must match the voltage you will run, too high a Kv and amp draw will be too high and prop size too small for good efficiency. A Kv of 1450 is too high for over 6S, the prop required to keep the amps reasonable will be too small. 8S and 10S boats run very well on 800Kv 56mm motors. How many FE boats have you set up?



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Old 12-01-2019, 10:00 AM
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35bertram
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I’m really new to rc stuff. Or haven’t played with them in 20 years. Lol. I did yacht restoration but closed my shop so picked up a lot of rc planes, boats and stuff to play with and build.

I didnt know they made a 150 size plug but that sounds better then the ones I listed. I was kinda stuck cuz of the small size of the connectors I was seen with what the boats draw.

I was planing on picking up a couple swordfish 8s esc for the 40” size boats they all run 1400 kv other then the m41 that’s still stock at 1800kv. I have a 1400kv motor in my 30” king of shaves hull. All the other 30” boats are 1800kv. So I’m debating moving the m41 motor into the king of shaves and the 1400kv dinamite into the m41 with an 8s esc.

I ran the king of shaves yesterday a little. It ran ok was quick didnt top it out. Ran on two 3s 50c 8000mah thro a 6s seaking 120a it’s turning a big prop will post photos.
Old 12-01-2019, 12:26 PM
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35bertram
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So 1400kv is to much rpm for an 8s?

just ran the m41 first time in the lake. Don’t need it much faster my lake is small. Lol. Maybe I’ll run 6s on all the 40” size hulls also.
Old 12-01-2019, 01:06 PM
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35bertram
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Your correct. I checked the spec on the motors that are 1500kv btw not 1450kv and max voltage is 24v so two 3s are about all they can deal with.
Old 12-01-2019, 01:21 PM
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35bertram
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What is the opinion on 40mm can 800kv motors. That look like that can take a 12s 54v. And the smaller can size means a cheaper motor mount. But are they able to make the same torq as a larger 55mm can motor
Old 12-01-2019, 01:27 PM
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35bertram
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So if I dump the 1500kv motor for a different project and drop down to 1250kv I can run 8s on my 40” boats. And can run 12s on the 50” boats


Still can’t post photos.
Old 12-01-2019, 06:52 PM
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Boats much over 32” should use at least a 40 mm diameter motor. The 36 mm motors are really not suited for 36-40” boats, they run better on the larger motors, 40x82mm or larger. Boats over ~40” should use a 56mm motor.

A 1400 Kv motor is just too much for 8S or more - unless all you want to do is a few speed runs. I ran a 40x102 mm 1500 Kv motor in my record-setting SAW hydro with passes over 100 mph - but only for two passes then back to the beach. A 56 mm motor is better suited, the smaller motors just don’t have the torque required to spin an appropriately sized prop. A larger prop - 60-70 mm - is best for a boat 40” or longer which means a maximum of ~800Kv for 8S and 10S, maybe 1000 Kv for 8S. More Kv will mean excessive amp draw and/or poor efficiency. Don’t try to reinvent the wheel, hundreds of others have paved the way.


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Old 12-02-2019, 10:33 AM
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. .


Thanks for the reply

all my 30” boats run a 1800kv 40mm motor 120a or larger esc 6s
With the 40” boats I was planing on running 1500kv 40mm motors 120a or larger 6s
now on the 40” boats im thinking 1250kv 40mm 54v motors with swordfish 8s esc with two 4s lipo so 8s battery’s.


Sounds like you think the 40” boats needs to be 800-1000kv
Old 12-02-2019, 12:32 PM
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Really was planing on running the 50 and 54 dumas moons and the 46” dumas hydro between 600 and 1000kv. Why I was thinking 1250kv on the 40” boats

Old 12-02-2019, 01:48 PM
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The black jack ran good with 6s 120a esc 1800kv today. Going to run the king of shaves tomorrow it has a 1500kv so we will de how it compares.
Can post photos next post!! Lol
Old 12-02-2019, 01:49 PM
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Last edited by 35bertram; 12-02-2019 at 02:25 PM.
Old 12-07-2019, 12:03 AM
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Is that last boat a Dumas Miller American with a Notre Dame/Valu Mart cowl on it?
Old 01-05-2020, 09:47 AM
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35bertram
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Originally Posted by Hydro Junkie View Post
Is that last boat a Dumas Miller American with a Notre Dame/Valu Mart cowl on it?

it’s a dumas atlas van line with an after market cowl. I also put zebra wood deck down so don’t know about it making any scale shows. Lol

i have a similar 36” That’s all glass but it’s a shovel nose little older style.

Old 01-05-2020, 09:59 AM
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35bertram
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Default Shaft size

So all my 6s boats other then the m41 are running 1/8 shafts. All are running 40mm motor size around 1500kv and on 6s.
I am rigging two boats 8s. A prathner 40” deep vee and dumas atlas van line. I’m running a 1/8” shaft on the prathner and 1/4” on the atlas. This just came down to the parts I have laying around.

seems like most factory 8s boats are not even providing a 1/8 shaft with there builds. Most seem to come with 3/16 size. So is 1/4 total over kill for a 50” dumas running 12s and the dumas atlas I have all ready started to rig.

I can not see the loss of to much power to the larger shaft size. I have a lot of 1/4 propellers and also have the shafts and struts all ready in that size. But after looking around seems like with electric guys are running smaller.

I know from building large shop air compressors for my yacht restoration shop that electric hp has more torque then Diesel or gas. Basic rule is to run a 5hp electric compressor kn fuel you need 10hp diesel or 15hp gas motor. All large 26-30cc gas boats run 1/4 I have even broken a 1/4 shaft on my 50” gas boat. Probably due to lack of oil in the strut. But still an electric boat capable of the same speed as an electric should produce less striating torque with a prop under load then a gas motor. So isn’t 1/4 “ appropriate.

Last edited by 35bertram; 01-05-2020 at 10:02 AM.
Old 04-18-2020, 04:55 PM
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On boats over 40 inches i use 1/4 / 6.35 mm flex and a 8mm prop shaft but then step down from drivedog forward to accept 3/16 props as you get a much better selection. All other boats smaller in length i use 5mm flex with 6mm propshaft stepped to 3/16 for prop as well. I have hit 110 mph with both size setups. Even though 5mm flex is very close to 3/16 / 4.75 it is much stronger. In United States its hard to find these size propshafts but standard 1/4 inch will work fine for most setups. I have twisted many 3/16 flex cables over the years. With the torque and rpm of brushless motors its very easy to snap a propshaft or flex cable. I have twisted the blades off props as well. For most hulls i try to figure out a KV and battery setup to stay around 25,000-30,000 rpm. My fast electric with Lehner motors generally run 35k-45k and sometimes higher. I use 6mm LMT gold plated bullet connectors. I have pulled over 400 amps on these during a saw pass with no issues.

It all really depends on hull, hull weight, motors used, water characteristics, and desired speed. Most of all how much money you are looking to spend.

Last edited by Chrisg81983; 04-18-2020 at 04:58 PM.

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