Hopping up with Brushless

[MumblinAviator]

I'm rather new to the R/C Boating community, but not R/C in general.

I plan on buying a cheap hull and dropping in my own components. My one major concern is how powerful the Brushless motor should be.

It'll be a 22" Deep Vee hull that probably has some weight to it. For a single motor application I've been looking at 3200-4800KV range usually intended for Helis and Planes. Bad idea? Would it work?

Any general insight is also welcome. Thanks!

[Rex R]

er, it depends. how many cells?(guessing 6) type of drive(subsurface/surface piercing), sport or all out racing? for sport use methinks I'd go with a 'Feigao 540 8l'(3072 kv), for racing the 540 8s would be my choice. water jacket for either application. as for a prop likely start with an octura x430 and work up from there. keep in mind that a 22" hull is kinda short for use with a brushless motor(not saying it can't be done... but you should be prepared to see the underside of the boat)

[MumblinAviator]

Anywhere from 6-12 Cells, Surface Piercing, just sport use.

I understand it's on the smaller side of things, but getting larger also means getting deeper in the pockets and I'm trying to make this thing a cheap "backyard basher" type project.

Thanks for the thoughts, though.

[MumblinAviator]

Bump, could use a few more inputs. I am completely unsure what kind of power these aircraft grade motors can put out.

[MumblinAviator]

Examples:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=003&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=130067576703&rd=1&rd=1
Looks to be about a 380 size, but would it be too powerful?

How about Something smaller like this...
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130071281866

I've read a few peoples experiments with the Reef Racer turning out that the brushless were a bit too powerful. This is a bigger hull and heavier, might be able to handle it.

Thoughts please

[fleetmaster]

One thing to keep in mind is that with boats,a lot of the time you are at W.O.T,so you need to watch heat buildup. A 380 size would be too small.
I would say that something like a 450xt outrunner on 3S lipo would really get going.
A mate of mine has a ply skinned depron mono with a 400 size and it rocks!
Having trouble keeping it on the water,though his hull is shorter I believe.

[fleetmaster]

For decent performance,i'd say that you want to spin the prop to 30000 + rpm.

[MumblinAviator]

So a 380 would be too small even if the rpms were up in that range?

[fleetmaster]

I believe it would be.You'd draw less amps/generate less heat from a larger motor.
You can get 450 outrunners quite cheaply and speedies to suit too.

[Deestingray]

I believe it would be.You'd draw less amps/generate less heat from a larger motor.
You can get 450 outrunners quite cheaply and speedies to suit too.

This will probably be my next step in getting some good power out of a small mono. If you can get at least a 3000kv 450 outrunner, I think you will be set for sure. Power it with a 3S lipo and it should be all good.
I have found with the 400, it is right on the limit. The way I had the other mono set up with a surface piercing prop, the strut was sitting a couple of mm too high out of the transom and something as small as a 27mm prop was just cavitating with not too much go forward.....I changed up to a 32mm and it went like a rocket literally, it had a tendency to go skyward when it had reached about 3/4 speed. It will also be necessary to cool the motor, these outrunners are designed as an air cooled motor. You won't be able to cool the can as that is spinning but you can cool the stator which will help.