Some newbie questions

[w00p]

Hi you guys.
I have no boat experience at all, but I'm looking at a cheap little "weekend project".
I'll need to know some things though before I can start anything.
First of all, how do you seal the hull at the propellor shaft's exit hole?
I don't understand it, you either have a leak there, or you have so much friction is unpractical...
Second, how efficient is the mechanical output of the motor into forward momentum?
Third, is torque steering possible with boats or is a rudder a must have?

You see, my idea is to strip one of my old toy grade R/C cars from when I was a kid, and port everything directly over into a playmobile pirate ship.
The R/C car I'm talking about doesn't have a steering servo though. It has 2 motors individually connected to one of the rear wheels and by only giving one of the two motors throttle, you steer. I can imagine you'd have to install the two propellors as far from eachother as possible, but is it possible to steer a boat like this?
An alternative would be connecting one motor to a prop and the other motor through some SERIOUS reduction gear box to a rudder. Then I'd have that last motor acting a bit like a servo motor, though centering the rudder would be quite a task. :o
I'm not sure if I can hook up a hobby grade servo to a channel for a toy motor...
Another problem is that its a toy "ESC" so the throttle for the motor is everything or nothing. (it has forward/reverse though)

Anyway, hope to have some stuff cleared up so I can start making plans.

[Anton70]

Hi Woop, Just a couple of answers to your Q's here as I am by no means as experienced like most modellers here. But my 2c:

With regard to the prop shaft the driving shaft (usually SS rod threaded at the prop end) runs inside a close fitting brass tube called a stuffing tube. This tube is sealed at the entry point into the hull and filled with a type of grease so that the shaft within still turns but doesn't allow water to enter the tube.

You can get steering from two motors as you describe, but it is fairly inefficient
compared to rudder steering.

I like the idea of the playmobil hull as my son has a couple of these and they could be good fun.

As for using one of the motors geared down to act as a servo, this sounds unlikely to work to me at least but others here would have better knowledge about this than me.

Hope this helps some what.

Cheers

[towboatjoe]

To avoid a leak through the shaft you need to build a stuffing box. There's a drawing on how to build one at http://www.towboatjoe.com/shafts.htm

You can steer a boat with no rudder, but you need twin propellors with seperate speed controls and it's best to have counter rotating props (right hand and left hand). I don't think you're going to turn the boat by stopping on motor, Maybe in the length of a football field. you'll need to be able to reverse one while coming ahead on the other to have good steerage.

Another option is using one prop mounted crossways to act as a thruster to push you left and right, but as with any single screw vessel they'll always be a tendecy forthe boat to pull in one direction because of the torque of the prop.

[patmat2350]

Before even starting with the conversion, make sure the thing floats. I tried a toy pirate ship once, and even after sealing all the openings and ballasting to the limit, it was fatally top heavy.
Pat M

[LtDoc]

w00p,
I think you've gotten the idea that differential motor control for steering isn't exactly the 'best' idea in the world. Why is it used at all? Cuz it's fairly cheap considering all the other stuff you don't need, such as servos, a 'real' radio system, ESCs etc. Using the motors for steering works good for aircraft (sort of) because of the larger amounts and effects of drag experienced by aircraft. Doesn't take a lot of differential thrust to make an airplane turn, but it does to make a boat turn.
As far as using a motor as a servo, don't bother. The amount of weight of the reduction gearing required will turn your boat into a submarine real quick. It's certainly within the relm of possibility, just not very practical.
'Patmat's idea is a very good one - lol! I've no idea what your boat is, so I won't offer any suggestions about making it work. (And considering some of the things I've tried to make work, you're better off NOT getting suggestions from me!)
- 'Doc

[w00p]

It floats, really good, believe me! :)
My little nephew used to come over during summertime and I had to babysit, he loved toying around with the pirateship in our fish pond.
It doesn't even sink becuase of the foam inserted in the hull. You can flood it, fill it with water, it'll float with the deck just above water or on its side.
And you really have to push it underwater and wait untill its entirely flooded to get it to that state, anything that could possibly happen with it in a pond couldn't get it to sink! Sounds a bit overqualified for a newbie like me! :D

Oh, and I know you won't turn a boat by only throttling one side, you'll need to reverse the other side, offcourse.
The servo thing was just me thinking out loud, it might have been genius, but most likely the most stupid thing you've ever heard. ;)

Can you get all the parts to assemble a stuffing tube in a regular HS?
I've seen some brass tubing lying in mine, looks perfect for the job.
What grease do you guys reccommend?

[Rex R]

last time I looked I could :). think usual practice is to use the next two sizes larger than your prop shaft (ex for a 1/8" shaft, using 5/32" sleeved inside 3/16" brass(I think that is to give the tube added stiffness)). some folks use lithium grease...while others use 10w-40 motor, or a combo of both, it kinda depends on shaft speed. hth
rex

[wingnut163]

STP treatment for oilis good.

[Umi_Ryuzuki]

last time I looked I could :). think usual practice is to use the next two sizes larger than your prop shaft (ex for a 1/8" shaft, using 5/32" sleeved inside 3/16" brass(I think that is to give the tube added stiffness)). some folks use lithium grease...while others use 10w-40 motor, or a combo of both, it kinda depends on shaft speed. hth
rex


Most of the parts can be found in the KS brass display at the local hobby shop, or Ace Hardware stores.

A little more on the stuffing tubes. :cool:
http://www.rcgroups.com/forums/showthread.php?t=437771

[waboats]

I like the idea of the playmobil hull as my son has a couple of these and they could be good fun.




I might be a little late on this Thread but I have had quite a good success with the Pirate Galleon from Playmobil.

Every time it hits the water the kids are amazed and all want to have a go..

It runs on a direct drive 360-14 motor by electronize with two channel control. Not for outside on the pond but a great indoor or sheltered water novelty. Uses existing ballast bulb and has a few extra Pirate bits & bobs for effect.


The Viking Boat is also a challenge, but dooable

;)

[Kmot]

Cute! :)

[keven64]

Hello waboats,

Any chance of some pictures of the inside of that Playmobil pirate ship ? :D
Amazing... ;)

Keven. :)

[waboats]

Hello waboats,

Any chance of some pictures of the inside of that Playmobil pirate ship ? :D
Amazing... ;)

Keven. :)

Keven

I'll see what I can do with the Camera over the next few days.. This is an old photo from a display last year.

Luv doing the crazy toys for a bit of a distraction. Keeps me sane..

Cheers

John

[waboats]

Keven

As promised some photos of the Insides of the Pirate Galleon.

I use a small Li-Po battery I got from a Heli I crashed & burned..

I have sponge around the electronics in case a small amount of water gets in. Not sealed and comes apart where the toy does. Only trade off on the hull was I glued the Gun Ports in place permanently.

Keeping it out of the wind is the trick..

Run Time is about 1 hour.

[keven64]

Excellent - many thanks, John... :D

I had ( it might still be somewhere in the cupboard ) a free plan from one of the UK model boat magazines - from about 20 years ago - that your pirate ship reminded me of...
It was a junk - with sails from plastic card on a pair of rotating masts.

Now I have more ideas for toys for the kids - including me... ;)

The sponge is a good idea. :cool:

Keven. :)

[waboats]

Now I have more ideas for toys for the kids - including me... ;)

Keven. :)

Doing a few R/C Conversion for the same show in August. Sinking Titanic @1:350 scale. Waiting for the MFA Como 12v Gear Pump to get started..

and just finished the Pooh Boat.. :D

Luckily I build these crazy toys so I can take the electronics out and use in other boats. Makes the hobby a lot cheaper.

I'll be glad when I finally get my Amsterdam Tug past the early build stage. Doing it as the French Naval Tug; Centaure of the Tenace Class. Time to get serious again. :rolleyes:

My Moto: when the kids grow up, Nick their toys... :o

[Kmot]

I know a Dad who would probably love to have that for his son!

u163665, you reading this thread? :D

[LtDoc]

waboats,
I like that one! Is it 'scale'? :)
- 'Doc

[waboats]

waboats,
I like that one! Is it 'scale'? :)
- 'Doc


1:1 Scale of the Disney Pooh House Boat. Got it from Target Department Store here in OZ... :) :)

The Graupner Kort Nozzle driving the thing is a bit overpowerd but effective for the job..

It does move on the Pond I guarantee... ;)


It's improved and now finished with Night Lights..

[waboats]

To keep the Thread alive here are some more photos of the conversion for the Pooh House Boat.

The Lights didn't come out well in the photo but gives an idea of what has been done. :eek:

Tigger & Piglet have been turned into Nightlights and glow in the dark. The House can be removed and placed in any room at night while the 2 AA's are charged. The kids love it.. ;)

The drive motor is a 360-14 Electronize (best little boat motors on the market IMHO..) Drive Battery and ESC are same as Pirate Galleon. ESC Fwd only as the Nozzle turns about 130 degrees each way, making the boat spin on the spot.

For those that noticed I have a pair of birds on board. R/C'd the Duck & Full Size Black Swan (West Oz native fauna emblem) so had to do a pelican. Maybe full size next year, if I can find a mold?

Overall the Pooh House Boat is 12" in length. My first Motorized Footy.. :p

I'll see if I can resurrect the Playmobil Viking Longboat I did a few years back.. That one was difficult, I have to admit.

The only limits I palce on myself when I start a Toy conversion is that the final outcome must have the same appeal and look as the original toy and it must be able to be used in a backyard swimming pool at the very least.

Cheers

John

[waboats]

And for the last one of the Playmobil boats I have converted to R/C.

Found an old photo but can't seem to place the Longboat. Looks like it might have gone back for the kids to play with, now there in their 20's..

Driven by Servo Motor and Micro Steering Servo with Cell Phone Battery..

Bit of fun but needed a longer rudder downwind..