discussion Rudderless boat and ESC's?????

[Guest]

Hi Guys,

Just got back from the bootfair with a nice speed boat hull. Its obviously some crappy chinese import but my friend and i had an idea! Its currantly setup with some dodgy ESC and two 340 motors. No rudder. Obviously to steer one motor turns one way whilst the other turns in the opposite direction.

Now we want to put some BEASTY motors in this just for jokes, maybe old black & decker motors, however the issues arise when finding an ESC that will cope with the voltages (proberly 9.6v).

Obviously it needs be able to link to the reciever and vary the voltage going to each motor to enable the boat to turn?

So any ideas or recomendations?

I'll try to get photos up this evening!

Toby

 

[Guest]

You can either source an electronic controller that can cope with your voltage, most do anyway, and current which is far more important. Check out the Mtronics range of marine ESC's.

Alternatively you could make what is known as a "Bobs Board" which is a flat board with a resistive strip attached to it mounted on top of the servo and the servo arm has a contact attached to it that wipes across the resistive strip, effectively varying the resistance to the motor. Take care though, the first one of these I made got too hot and melted the plastic servo arm. The first experience of paddling after a boat! After that I made a cooling coil for it and it worked fine.

These are very simple and cheap devices and can still be obtained. I used to have one in a Tamiya car I am not so sure if Tamiya still make them and they were OK for 7.2 Volts. 9.6 shouldn't be a problem but you need to know what current you are dealing with. Put an ammeter in line with it and test it but make sure it is in water as the current is a hell of a lot less when it isn't in the water.

The problem with a B&D motor is that it won't spin very fast and for a performance boat you need the revs. It will still be interesting to play though.

My Badger boat, in the gallery, has a large 24v motor from god knows what source, powered by a 12v motorcycle battery!! It doesn't have the performance but it goes forever!

 

[Guest]

Are you going to be using 1 ESC per motor to control it independently or are you going to be using some sort switch to switch off/reverse a motor when turning. As Richard says, most ESC will cope with 9.6v, its the current thats more important.

 

[Guest]

ok squiff,

first of all you`ll need two Esc`s . most boat ones are rated to 12v , others upto 24v. as mankster has said it`s teh current draw thats the problem.

obviously two motors are required,

now, more expense, you can do the mixing operation of teh motors by your self, or you can pick up a mixer which will do this for you.( around £25 ish)

ideally two nicads , but one would do. you can pick up 9.6v packs quite reasonably.

all on all cost builds up very quickly.your looking at around a £100 for the tehrc stuff alone.

my m8 picked up a brand new twin motor speedboat, with full rc fitted, running two strudders . i`ve only seen this run on one 8.4 v pack, it`s designed for two, and beliege me it`s quick !!

£155 on ebay , a traxas boat.

 

[Guest]

cool, thanks for all the replies guys!

Well obviously, im a cheapskate and this is a long termish project so i will be doing most of it myself!

The batteries are 9.6v 1200mah and i have lots of them (airsoft size) so will use these. Motor wise im thinking 540's or the EG1000's which is an airsoft motor that all the car racers seem to rate very highly as they have large amounts of torque at high rpm's. Both will take a wide range of currants.

Richard, you spured the idea im thinking of at the moment! Using two tamiya car speed controller board thingy wotsits. The only thing i have a problem with here is working out how big the fuse should be etc!

Adam, it might cost the £100 brand new to get all the bits, but im sure using the stuff i have littered around the office, and my fleebay & bootfair skills i can drop that right down to pennies!

Mank, ill either use tamiya ESC's or those PCB type boards so i think 9.6 should be fine through those as most tam cars take 9v fine?

Ive attached my diagram mk1. (this took like 10mins but it gives you the idea)

 

[Guest]

Short burst of pleasure

Hello all, Squiff !! A pair of 540 motors drawing off a single 1200mAh battery will last less than 5 minutes !!! even if you reduce the prop size to a 2 bladed 20mm one. Have a re-think on the batteries and try to get at least a pair of 2000mAh ( 1 for each motor ) otherwise your diagram was perfect. Edit : And when using a pair of batteries I prefer to use a dedicated Battery pack for the RX

cheers

Jim

 

[Guest]

Hello all, Squiff !! A pair of 540 motors drawing off a single 1200mAh battery will last less than 5 minutes !!! even if you reduce the prop size to a 2 bladed 20mm one. Have a re-think on the batteries and try to get at least a pair of 2000mAh ( 1 for each motor ) otherwise your diagram was perfect. Edit : And when using a pair of batteries I prefer to use a dedicated Battery pack for the RX cheers

Jim

Hey Jim,

The thing is i have LOTS of 9.6v batteries, all of which are 1200mah, i also have a mutlibat charger so theres not really any problems there i dont think. I like the idea of running one battery per motor, that never occured to me! Will re-do the diagram tommorow when im a little less drunk, lol

 

[Guest]

Squiffy,

Look at the HMS Cossack model in the gallery. She has two motors, one on each shaft, each with its own speed controller and each with its own 7.2 volt Tamiya pack.

The radio is set up so that the left stick controls the Port Motor, Fwd stop and reverse, and the right hand stick controls the Starboard motor.

Apart from being very intuitive to control it also had the added advantage of having total redundancy, so when one ESC burns out the other one can bring it home.

I also had the right hand stick for the rudder and the left hand stick operates a siren and a smoke generator.

Although it is a set up used quite a lot for little pusher tugs etc I think you will have a serious challenge trying to steer a performance boat with this method. The balance will have to be perfect on each side so you would need to use the trim tabs to set up a straight course and steering will probably be so sensitive you would run a risk of it getting out of control.

It will be certainly worth watching!!!

 

[Guest]

I had a look at the photos, nice ship, god knows how long that superstructure must of taken! I didnt see any interoir shots however!

Is there a certain term for this sort of setup so i can google it? im not having much luck at the moment!

The whole project is a "bodge-a-lodge" laugh for my friend and I. I doubt very much it will work, and if it does it will sink on its first outing! However every glourious second will be captured on film!

....mind you i have some serious oil time due with the bike so its going to be a long term thing!

 

[Guest]

If it was me, I'd put a rudder or two in it with a servo. Much better steering and less troubles to my mind anyway. That's just me of course.

Jason

 

[Guest]

just to update this thread a little:

Bought a Ripmax speed boat for spares so have combined the two. Put a new 22T motor in it and replaced the servo controlled speed controller with a tamiya ESC rated to 9.6v. Removed anything that has any weight to it and changed the rudder postioning so full left on tx means the rudder will right angle itself.

Tested last night and she actually ran really well perfectly until the battery died, much to the surprise of my friends and i. The most fun was whatching the front rise a good couple of inches as you got the power down.

Only bad point was a heavy reverse will send a sunami over the rear swapping the delicate insides, im going to waterproof them completely tonight.

Pics and onto 12v coming soon!......

 

[Guest]

You need to set the speed controller up if possible so that it cannot give full power on reverse. It depends on the ESC itself as to how and whether this can be done but the danger is that should you loose control, such as radio batteries die etc, and it goes into full reverse the boat will swamp and sink.

 

[Guest]

ARHHHH how obvious! nice one!

yeah you can actually fully adjust the amount of power going through reverse or turn it off completely. Im very impressed with these nbew Tamiya ESC's!

We took the old girl down to the quay yesterday, beautiful day and i was rather worried about sailing it in the river where theres a strong currants and waves etc. Bloody great, it took off over a couple of waves and there was quickly a crowd of youngsters whatching!

All was going well until i started a full right rudder full power turn, did three of these in quick sucession and then lost ALL rudder control, it was stuck full right (or should i say port?) so i had to use the currants and some nifty forwards/backwards motions to get her back!

On inspection i found i had full ESC control but channel2 and the servo were not moving. I unplugged the battery pack from the rx and plugged it back in and everything was fine! I thought maybe this could be that the batteries were running out? they are the rechargable type?

Or maybe because i was laying full power down and full right servo the rx got confused? (it is a rather crappy basically futba/ripmax thing...)

Once i get my cam back i'll get some photos

 

[Guest]

Right Rudder is Starboard but I get the idea!!!

if you have power for propulsion you should have power available for the steering servo.

I would very carefully check all connections, particularly with second hand gear where the contact faces on plugs etc may not be in the best condition.

 

[Guest]

The power for the servo comes off a seperate battery pack (4aa's in a holder) and the power for the motor from the 9.6 jobby. I will check all the connections now. Although i think im going to change the rx and tx to see if that makes any difference as the ones im using are shocking!

 

[Guest]

you may also have found that if the rudder was hard over it jammed the servo (especially if older and second hand) , the servo as you probably know contains a tiny motor and gears, you may have been forcing the motor and geears to remain jammed (it would have been under motor stall conditions)

this could have drained the 4 x AA battery pack quickly or actually forced the servo to ' lock up' , by releasing the power by reomving the lpug things then ' free up' and everything is normal again,

 

[Guest]

Time to update this thread a little...

Well ive now stripped the ripmax boat after having quite a bit of fun with it, got it to a good 25mph+ on the 9.6v bat with a 22T motor and 2 bladed prop.

The new boat im informed will be quicker as it has 2X motors powering 2X two bladed surface skimmer props. I have added a rudder with bearing just behind them so i will give this ago. Although after my research i noticed all powerboats had their rudders behind the props...ops live and learn.

The other thing im looking into at the moment is the fact the motors are crappy little 380's which dont run too smoothly, let alone with the 7 celled bats so im thinking some nice 540s or 600s would be good.

Alas, as everyone said the two bladed props dont half drain the batteries, can anybody remmbered some good sites to order single cells from as i prefer to solder my own up rather than pay a premuium for ready made?

As i keep promising i will get some pics up shortly, just been very busy at the moment!