Cat with no rudder?

[Steven Vaccaro]

We have all seen those cheap toys with no rudder(or fake rudder) and twin motors. By varying motor speed they turn. Has anyone done a faster boat trying to use this method?

[steveo]

i would think that you would alot of lake to turn that boat with a drive system like that

[Steven Vaccaro]

I wouldn't think so, all the drag that the slower motor creates should make it turn or spin out rather quickly. But you may be correct. Who knows until its done.

[domwilson]

I had a NQD High Wind with dual 480's in it and an 8.4v battery pack. Worked ok till it burned up the combo ESC/Receiver unit. Was faster than the stock boat for sure.

[vvviivvv]

my big scale boat is on independent throttle control but it is a twin jet boat, running it on only 1 motor makes little to no difference on the direction.

[Spot Me 2]

my big scale boat is on independent throttle control but it is a twin jet boat, running it on only 1 motor makes little to no difference on the direction.

Your jets are also right next to each other. The drives on a cat are pushed out to the outsides of the hull. If you push any hull from the center it will want to go straight, but if you push it from one of the corners, it will want to turn.

[sundog]

Your jets are also right next to each other. The drives on a cat are pushed out to the outsides of the hull. If you push any hull from the center it will want to go straight, but if you push it from one of the corners, it will want to turn.

A dual jet drive doesn't have anything to cause drag on the opposite side of the hull - like a stopped prop. So it will still want to go (fairly)straight.

What Steven is describing is vector steering, and the toy versions steer surprisingly well. Tugs, mules and ferries (sounds like rugby teams) all can benefit by having one drive go one direction and the other the opposite direction for on-axis steering.

It would be interesting to see a fast electric version. It stands to reason that three bladed props would increase drag more, allowing better steering at higher speeds (without having to drop rpm's as much).

[Amp User]

It will steer great, son has a mono cheapo dual motor we ran it thru beach waves tracks like a tank.. just add some skegs to help with the prop push and sliding with fast mono's. A cat may by nature fare well without any help.

[vvviivvv]

i could try it on my 115... i have a 6 channel remote / receiver airplane style and some beefy 3 blade props...

would have independent ratchet throttles.

edit: heres a vid of a twin cat on 1 shaft but the other 1 isnt there to create drag

http://www.youtube.com/watch?v=8SRAKrfA3V4

[questtek]

Steve,

You might find of interest two Avenger Pro 44 Cats from Aeromarine that have such a set up without a rudder.

I developed the first version many years ago for NOAA and marine research. It had 3 video cameras onboard, wireless transmission system, computers, etc. I delivered about a half dozen of them for use in marine monitoring and education. A follow up reply will show their use in Hawaii monitoring salinity changes along the coastline using shore based operators and observers.

The key here was to make the boat turn 360 degrees in its own length. This was necessary for the UW camera to be effectively controlled and rotated around an underwater object of interest. The dual outboard motors in the red housings run off 3 LiPo pac and have been designed for years of continuous submersion in saltwater. They are brushed motors that run forward and reverse permitting the tight turning and rotation ability.

You will also notice a third conventional shaft for a flex cable drive from a brushless motor inside the hull. This gives speed to get to the location of interest. I have a black plug on it now since all my work has just slow speed requirements. I would definately class this boat as a SE and in NO WAY a FE!

The second concept I have been working on is shown on my bench. It has two brushless inrunners that are oil filled. They are designed for freshwater and not saltwater operation like the previous motors. These will operate off 4 cell LiPo pacs and have even more sophisticated electronics that the previous version. The motors I am using are 4-pole motors capable of about 2500 watts continuous. My FRESHWATER testing of these motors has been great and I am impressed with their inwater performance. The question now is just how fast will they make this boat move?

My goal is not really a FE but a moderate speed, stable, miniature oceanographic platform that can be used for research and education. I hope what I learn in my testing can be applied to all the guys in this form who REALLY want to go faster....if it turns out that way. What I gain in reducing flex shaft losses I more that make up for on increased drag from the motors being in the water.

[questtek]

I found some of the old pictures of the first version of the Cat with NO Rudder Avenger Pro 44 being used for research and education in Hawaii. The wireless system permitede underwater, topside and instrument video views, all selectable by the operator using a conventional HiTec 6 channel transmitter/receiver.

[VooDuuChild]

I've got a cheap toy vector steer (at least it's pretty quick as I've seen vids of a Rio EP and that doesn't look much faster than mine). I have never seen anything turn as sharp as these things do. Yup, it's a toy, yup it's not the fastest; but it'll stick around as a buddy boat for those who wanna drive my soon to be hobby grade boats. I don't see why it wouldn't work on a faster platform and it would be interesting to see it done that's for sure. For it to work well, it would have to be proportional like rudders are instead of just dumping the power to one motor......

[sundog]

Could you use a rudder mixer - like for a v-tail airplane - and plug esc's into it instead of servos - would that work?

[damfurst]

I've wondered the same thing too Sundogz, but I think these will work for surehttp://www.cornwallmodelboats.co.uk/...iks_wtail.html Wanted to try one on my twin jet drive but havn't gotten around to it yet.

[VooDuuChild]

What about a simplified version, tank like; both sticks move up and down, up full on, down full off?