woody_294

Formerly, Help for a Newbie! Electric non-racer.

My dad has a half finished boat that he'd really like to get working as something for him to do. It's about 3' long made of wood, and the hull and the deck is all done minus some superficial things he wants to do. It does need painting though, so anyone got pointers on that?

He's asked me to sort out all the motors and controls for it as I'm an electrical engineer (dad's a mechanical engineer ), it's going to be electric because I reckon that'll be the easiest one to maintain/install.

Plans!

The plan is to have 2 motors with props and a rudder per motor. From what I understand I'm going to need 2 direct drive motors for the props, not sure on which ones yet, with an ESC, batteries and an RC interface of some kind. is the only sensible way to control these individually? Because if that's the case then i suppose I'd need 3 channels to have the rudders too, and control may be confusing.

I'd planned to control the rudders together, mechanically ganged, with a single servo which would be controlled by the left/right joystick on the controller. Obviously this will be a problem if I have the motors controlled individually because then I'd be using a twin up/down controller.

Sorry for what is probably some terrible terminology, RC wise and boat wise! This is all new to me, I've only had experience with my Nitro car before.

*Edit* Can it have reverse too???

Ron Olson

My Feedback: (1)

OK, I'm certainly no genius when it comes to electric boats but I'll take a stab.
You might be better off just running the twin motors without having them running independently as that alone will save you a lot of trouble. Unless you're looking for a lot of maneuverability this is your best shot. Don't try to over-engineer the boat.
Unless you're building something more along the lines of a scale ship you could also go with a single motor setup as there are plenty of motors out there that can easily handle a 3 foot long boat.
Not specifying any more than the 3 foot long boat really isn't telling us that much either. Looking for speed or just putting around?
Yes, you can have reverse.

stubaz

My Feedback: (1)

I've just finished my first electric boat and the learning slope was a bit daunting at first but checking the Net made life easier and using a little Googling and finding friendly advice on forums it was pretty simple really. Mine is a single water cooled motor connected to a 120 amp ESC with a BEC. I always make sure the ESC has a BEC so I have a constant supply of 6 volts to my receiver, much better than worrying about a 4 pack of AA's plus handy for anything else you want to power. I used just one 11.1 battery to start off with but after gettuing used to the boat I intend to change to 2 7.4 volt lipos to give me 14.8 volts for some extra power and speed it's even possible to go with two in parralel plus another 2 in series to give extra run time. More volts and more amps in steps helps with getting used to the boat slowly instead of a fast boat straight off. The cooling is simply water picked up via the rudder and its forced to the motor and then on to the ESC then spat out through a small vent in the side o the boat. When I increase power I will run a dual system with one inlet to the motor ans a seperate on to the ESC for extra cooling. Fitting it is a breeze.

As for the steering just buy a dual rudder assembly and one decent servo and one channel will take care of that. A couple of trim tabs and maybe a turn fin is about it. so from a simple single motor, ESC cooling system, and a dual rudder (although not always needed) you can grow into a real beast of a boat by simple wiring and an extra cooling loop. Buy the big motor first rather than changing and costing more money when you want more power and get the big ESC as well for the same reason. Then just change your batteries to suit what you want.

I'm no expert and I'd imgine others would do things differently but I'm happy with my boat. A little time spent trimming and adjusting the angle of the prop is all you have to do when you first get her wet and away you go.

Later some experimentation with different props can change the boats speed again. So keeping it simple to start can give you a chance to grow with the boat. Rather than going all out first up and having a beast which is hard to handle and costing a fortune. So you can virtually have a new boat every time you make a change plus it's easier on the pocket

Kepp reading and asking question and you'll be runing your boat in no time, good luck.

Stu

mfr02

What kind of boat is it? A 3 foot long tug has very different requirements to a same length speedboat.

woody_294

Ron Olson

My Feedback: (1)

I know how Engineers are! You'd LOVE scale ship modeling!
I'll take a shot at the other questions.
A BEC is a Battery Elimination/Eliminator Circuit, a trademark actually for using the main battery pack for an electric powered boat to drop the voltage down to sometimes 6 volts to power the receiver so no separate battery pack is needed.
Trim tabs mount on the transom to help fine tune the ride height of the boat when on plane.
Traxxas and some other manufacturers make ESC's to power twin motors but I honestly couldn't tell you if they have reverse but my guess is not. You can't mix that one either. This is something that I'd ask in an electric or scale ship forum.
Pleasure boats also fall into a lot of categories from Chris-Craft types to cabin cruisers. If you're trying to replicate a twin screw boat then you might want to go with twin motors. There are options galore for those as you can go with counter-rotating motors and drives, gear boxes or single motor to a twin gearbox drive. You shouldn't need any monster power to push the boat along nicely. A Mabuchi 500-600 can motor or a ROAR stock would be fine.
Here's one link that might be of help to you: http://www.mackproductsrc.com/index.htm .

woody_294

Ah right I get it, so a BEC is basically a 6v regulator so I can run my reciever kit off the motors battery?

mfr02

BECs are normally set at 5 volts, that being a de-facto computer component standard (look for LM7805, the worlds commonest voltage regulator), and of course we are secondary users of others technology.

woody_294

Found out what it is! It's a Sea Queen, 46" long and made from marine-ply:

pompebled

Hi Woody,

4-6 knots is walking speed...
Look here, I think your dad will like this better:
http://www.youtube.com/watch?v=OD9dn...e=channel_page

If I can find the thread on the Mayhem forum I'll post the link here, or take a look yourself...(enter "Huntsmen"in the search function in the Power, Race, Leisure & Sports Boats section and enjoy the read:
http://www.modelboatmayhem.co.uk/for...php?board=91.0

The boat in the video is powered by a large outrunner, geared down (or up, can't remember)...

Regards, Jan.

woody_294

Thanks jan I've asked the guy whose huntsman that is

woody_294

Ok! After lots of reading, I am slowly getting my head around this. For all intents and purposes I'm looking to get the a simliar, if not better performance to an MFA 850 Torpedo from a brushless motor, because brushless motors are more efficent, which helps me out in wanting to make the batteries last longer for better performance, if I understand this.

I've think I'm after about an 800kv brushless for 12v, giving me the max of about 10k rpm of the torpedo. What I can't figure out is why the brushless motors I look at around the 40 Amp mark! What Amps would this pull whilst doing 10k rpm pushing the Sea Queen through the water on say, the stock prop, which is a 65mm three bladed brass one.

[rant]

On a side note Wesbourne Models reckon that this motor is ideal for the sea queen, and frankly it looks like a monster and would last not much time at all on a lot of batteries. So WHY!? is this comparable to the Torpedo 850? I am totally lost on this front. Should I be looking to FILL this boat with Ni-Mh or Li-Po batteries to last an hour with all this new motor technology? [/rant]

I am fairly sure that with time and revision, motor technology has not gotten worse, so it MUST be that I am understanding this all wrong, please help!!

nick_75au

A 65 mm prop is a big load, as rpm increases amps go up at an exponential rate, Ive got a little pancake brushless that is quite happy to spin a 65 mm prop at 3500 rpm (at 6 volts) if I double the volts to the same set up the motor draws double the current, but the power goes up 4 times, this makes that particular motor very unhappy. To spin a 65mm prop at 10K rpm is going to draw around 40 amps regardless of powerplant, the MFA motor is not going to spin the prop at 10K, maybe 60-75% of that so 7500 RPM.

I would consider dropping the prop size, 50 mm or so is big enough, a low KV 42 series brush-less would easily drive that prop or a 3:1 -4:1 geared 700 series brushed motor on 3 cell Lipo or 10 cell Nimh. If you decide more performance is required then you can increase the cell count, but run times will reduce.
Look at ACTion electronics

http://www.action-electronics.co.uk/wd.php

Lots of single twin and triple set-up diagrams

Brushless , you will need 2 ESCs if you run 2 motors, brushed motors can get away with one ESC but you loose the prop steering capability

Hope this helps

Nick

HS93

If you are going to gear it go for two to one, we did a lot of messing about with gear ratios on heavey boats, we found between 2to1 or2.5-1 was the max any thing more and your prop gets to big the change from direct drive to geard gave us a small increase in speed BUT about 20% increase in run time, we did gps tests and amp and volt tests and used a lot of prop shop props in the tests this was over about 12months with a lot of test and gear ratios, and yes i am the same person who did the running gear for the Huntsman pompebled posted ill post some of the gear boxes.
Action Kits do not do anu brushless equipment as far as I know.
Peter

HS93

Hear is a Vid of Pauls boat it is fitted with astandard 700bb and 2-1 geares as in pictures, we also did gps tests you can see it in the read compartments.paul did all the hard work I just did the bit of metalwork I am sure if anyone needs info he will come on hear as I think he is a member, we moved to the Huntsman with what we had learned from this and it went well on the setup of a 700bb but as it is a big boat it was not fast enough for Paul so we went brushless this did improve things dramatacley we then tried Lipol this also made a difference but more so as the cells where getting old, anyway so pictures of the two set ups, very simple and a lot lighter than you think as there are a lot of lighting holes, just a final note the fire boat pre gearing ran red hot in fact we tosted more than one, on fitting the gears it now runs stone cold, we left the cooling on as it was there and in case we try other props that are a bit bigger, the props are two we decided upon one gives a bit more speed the other a bit more run time, so depends what you want Paul has also got a set for the Huntsman he has done all the work on this one as I was not to well this year, and has prob done a better job as he has done a massive amout of testing and moaning (sorry Paul) to get it to thunder around the lake.


http://www.youtube.com/watch?v=IprCPeNuAzc

HS93

this is the geared Huntsman 42" on a windy day running 16 cells and a 2.4 to 1 geared 700bb with a cleaver 4 blade brass prop, this boat weighs bout 6.5 kl so about the same as the Sea Queen.

http://www.youtube.com/user/onehs93#p/u/10/YgmVN3tIsyE

Peter

GETUSUM

My Feedback: (7)

I run Gas boats from 42" to84" and looking for a recovery tug,,,,does anyone have one with the power , or reccomend one to get them dead in the water to flipped???

this atlant harbor tug seems a bit small, but my Darby, is to big to lug aroung, plus if someone hit it, wel ther would be dead,,,recomendations ????

or 1 for sale??????????
Richard