EeZeBilts usually use a simple 5" timplate prop and rudder shown here. But one of the defining characteristics of a tug is the BIG propeller assembly at the back.
I originally wanted to put a Kort Nozzle on the Beaver, but felt that it might be a little complex. However, I did go for a large prop. It is made exactly the same way as the usual EeZeBilt props, but stretches the limits of what is possible using sheet from a tin can! The patterns for a few props from 1.3" to 1.5" can be downloaded here.
Ideally, 0.015" brass sheet would be better for the 1.5" prop - but tin cans are cheaper! If you want to use a commercial prop, note that there is not a lot of room, and you might want to move the rear part of the hull where the prop-shaft emerges forward a 1/2" or so to give better clearance...
The rudder is also a non-standard EeZeBilt item. It needs to fit in a small space and yet provide a lot of turning force. Download the lines from here, and see how it is made up below:
Mounting the rudder cheaply is going to be harder! I bought a strip of electrical connectors from a cheap market stall, and cut one of the brass connectors in half.
Here you can see it with a scrap of brass I'm about to bend...
We also cut two short lengths of brass tube, and solder a washer onto each one...
Another view, showing the top bearing better, and a rather poor early propeller....
But it's certainly big. And big's what counts with tugs...
Here are the completed parts - A tiller arm, a top bearing for the rudder and a bottom rudder tube.
One last point. If you are doing a hi-motor version, the end of the prop-shaft will be about 1" UNDER the waterline. Water will be able to seep along it and into the boat.
This can be prevented by making a simple seal out of a small length of silicone tubing. If you use a 1/8" prop-shaft, then some 2mm ID tube from ebay will work nicely.
A short length is slipped over the prop-tube, leaving just a short overhang to contact the prop-shaft. Too much and there will be excessive drag. With the right amount, and a drop of oil, the drag will be hardly noticable, and no water will get through...
Making the rudder blade is fairly straightforward. Bend a groove in the brass, and then solder a 1/8" brass shaft to it.
The top bearing goes in the deck, while the rudder post goes in the sub-deck, both epoxied in. The rudder shaft goes up between the two, and the tiller arm fits in the little 1/4" gap. Check for easy rotation and internal clearances. Drill the tiller arm to suit your push-rod...
