Hi Fellows

I wanna share with you the construction of my tugboat PARAT from Graupner.

Any comments, suggestion would be welcome.

The construction began the 5th of nov.


















More to follow in the coming days....

Wow, looks like you are making quick progress.
Is that the pump for the fire monitor?
Seems like you may only get a little stream from that
diameter hose. We are planning for 3/16" - 1/4" ID hoses
in the fireboats.

Nice job. It seems your VSD tug will get finished before ours.

You certainly are progressing! I was looking at a tug hull using these drives - have to convince myself to start another project.
My understanding is that they use only a forward speed control? The steering comes from the drives and controls? I'm hoping to see a photo showing the servo/drive relationships.
Nice work!

Thanks !
I will take a shot of the servos configuration. You need 2 servos / VSP.
Here is a scan of one page of the VSP instructions.

.....Let there be more light !!! :

Michael,
Take a look at Friedrich Prossegger's web site.

http://members.surfeu.at/fprossegger...-function.html

He built his own VSD. Their are some nice links to other images of his drive, and constrution.

Since we are scratch building our boat,
I am really glad we don't have to build our own drives.

I'd be interested in where you find these lights. Any hints as to wiring them up to hide the leads?
Presently trying to sort out how to make a tow winch operate - anyone know of a source for a small belt for a drive?

Try

http://www.smallparts.com/

Or

http://www.wmberg.com/

It's not cheap, but they have the parts.

Hey Mike,

I used christmas tree lights indeed. They are 6V and 12 V. The main batteries are 12V in parallel.
For more powerful light, I will use white bright LEDs .

You can find these lights in every hobby shop or tool store. The LED, in an electronic shop.

Now here is the part 4 of construction : more details (railings etc...) and the beginning of the retractable mast system :

Super and helpful details of construction. Thank you. However, all the helpful stuff which you and Umi put up still does not help me understand how the 2 servos attached to the V/S unit work when they would appear to conflict with each other, being in different plains. I see no sign of sliders or twisting collars. Can somebody explain, please?

Hi Roger

I understand your astonishment, myself I was wondering how it could work before I can see it with my own eyes.

Simply, the pushrods are connected to the servo arms with an attach that can let them rotate on the servo arm.

There is no conflict as the rod is free to move on a vertical axis and the distance of movement are so short that there is no need of sliders.

Hope this helps,

pics of the system soon.

Thanks for the reply. That is helpful.

I saw a Graupner V/S unit on Saturday at a show, on a trader's stand but as it was not connected to anything, I wondered. I thought the small range of travel was the probable answer together with swivelling bosses.

I am looking for a suitable hull in which to install a unit. But as I take a long time to plan and even longer to build....do not hold your breath! The joy of retirement, both the money and time to do what I want, well almost. Now, where is the paint for the outside of the house and I must rehang that gate etc. etc.

Essentially the two servos are mounted at a 90 degree ofset from each other. One servo will control the X axis, and the other will control the Y axis. The two servos working in syncronization are then able to move the "joystick" in the center of the drive to any position in its 360 degree rage of movement.
The "joystick" floats in the center of rotation, and does not spin at all.

First assume we have a drive rotating Clockwise.
While this stick is centered ALL the "blades" will spin around the circle in a linear fashion. No thrust will be created.

Now, for the sake of argument lets say that pushing that sitck forward make the drive propel the boat forward. (it actually won't). So for examle, If you push the stick forward,as each blade crosses the top of the circle (12 o'clock) it is angled to catch water, and thrust it into the center of the circle. As each blade moves to the 3 o'clock position it returns to neutral and slices thru the water producing no thrust.

Then as it reaches the 6 o'clock postion it is angled to pull water from the center of the circle and thrust it out and back. Then again at the 9 o'clock postion the blades are at neutral.

In actuality, the thrust occurs 90 degrees in the direction of rotation from the postion you place the "joystick" on the drive.
So in a clockwise rotation if you place the joy stick at 3 o'clock, the the thrust will occur at 6 o'clock. This is what the diagrams are actually showing.

Here is another diagram that I got a few years ago from one of the engineers at the local Foss offices( a tug boat company).

It also diagrams the control linkage of a Voith tractor drive.
notice that the connection of the linkage is behind the point of rotation for each blade.

[Edit]
Oh, Antoine,

The boat is really coming along nicely. I need to finish up some work, and get some boat time in on my fireboat.
You are making way too much progress.