Australian RC Forums banner

Boat enthusiasts, need help.

2K views 3 replies 3 participants last post by  ChaKane 
#1 ·
Hey Guys

I got a Robbe Najade boat with standard motor in it, im wanting to upgrade to brushless, Ive seen the variety of motors i can get as they have a 5mm shaft and thats what i need but need a hand with a few things.

What does the KV mean on the motors like 3072kv, 3870 kv, the higher the number more power or........?

Here are the motors its about the first 4 rows i can get, as they have a 5mm shaft. Which ones are the fastest with 5mm shaft?

http://stores.ebay.com.au/RC-Boat-B...QcolZ2QQdirZQ2d1QQfsubZ10519173QQftidZ2QQtZkm

ESC, what esc can i use, ill be running NIMH as well as Lipo, im looking at the $120 dollar one and the $160.

http://stores.ebay.com.au/RC-Boat-Bitz_ESCs_W0QQcolZ2QQdirZQ2d1QQfsubZ377519017QQftidZ2QQtZkm

Now i presume using that ESC and motor everything should word?

Some of the engines descrition they have like 6XL, 11XL, 8L, 15S, what does this mean?
 
See less See more
  • Like
Reactions: ratfink
#2 ·
higher kv the more speed...
lower kv more torque..

im running a feigao 12xl(1390kv)in my hyper st pro..

how heavy does the boat weigh??

my truggy weighs in at 4.9kgs so the lower kv works well to get it moveing..im running 6s lipo (22.2v)and geared for 40mph..

so if your boat weighs under 4.5kgs then id say go for a higher kv motor..

im sortave new to electric myself , so i could be wrong..just trying to help:thumb:
 
#4 · (Edited)
The KV will also give you how many revolutions per volt the motor will provide. As an example the feigao 12xl(1390kv) will give you 1390 revolutions per volt. This means if you run a 7.4 volt (2s1p) battery pack your motor will output 10,286 revolutions. 14.8 (4s1p) park will give you 20572 revolutions.

The more revolutions the faster the speed up to a certain point. Beyond that point, depending on the boat size, weight, setup, and a whole lot of other variables, you don't get much more bang for your buck.

What ratfink said is very true, the faster the motor the less torque it will produce which is important in the take off and when coming out of the corners to get your speed back up.

You should workout what voltage battery you are going to run, then consider the weight of the boat you are trying to push, the type of hull and then you can workout the best brushless to run with.

The S, L and XL denotes the size of the casing for the motor. You wil need to ensure that the case will fit into the area of the boat you have. The larger the motor the more torque you can generate but you need to be able to fit the motor into your boat. S is 51mm in length, L is 61mm and XL is 74mm. Just be careful of using the pictures on that site to select the motor as they appear to be all the same picture regardless of the physical size of the motor being advertised. You would be better to go by the description of the item.

In relation to the ESC, get the biggest one you can afford in terms of amps they can handle. 45amps is way too small for the boat you are talking about and you will burn it out very quickly. You need to remember that a boat will use far more amps than a car or plane due to the density of the water it needs to push. You will be saving youself a lot of heartache and cash in the long run.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top