Dumas  1-3/4" 3 Blade Bronze Prop for 3/16" shaft.

Dumas prop No. 3115. 2" pitch. Nice shape although it was a little hard to balance. Balancing instructions were included. PropDumBr01.jpg (31073 bytes)
Note the very long hub and deeper than we need slot for the drive dog. PropDumBr02.jpg (12579 bytes)
I "carefully" ground away the front hub and drive dog slot. To ensure it was square for good contact with the tug's drive dog (and so square to the stern tube's bearing) I inserted a shaft into the prop and lightly spun it against the sander to avoid an angle on the face of the prop. Wear a dust mask. PropDumBr03.jpg (53616 bytes)
I also shortened the hub on the back (prop nut) side as far as I could without sanding into the tips of the blades. Here you see the 1/8" nylon pressure tubing I used as a sleeve so this 3/16" shaft prop would fit the tug's 1/8" shaft. PropDumBr04.jpg (29867 bytes)
The balanced and polished prop looks like this compared to the stock prop. It could use finer polishing on the surface but I got lazy. Note how the hole looks a little off-center. That may have been the source of my balancing difficulty. PropDumBr05.jpg (25539 bytes)
Finally, I ground a small slot for the drive dog to engage. Trial and error to make sure they fit together. PropDumBr06.jpg (21988 bytes)
This is the mounted prop. It has a nice scale look compared to the plastic prop. However, for the price of this brass prop, you can buy a dozen plastic props. Still, this looks NICE! PropDumBr07.jpg (25211 bytes)
With 7 cells, you have power to spare. At full throttle, note the swell at the stern. It is up to the rub rail. With 6 cells you get to "hull speed" in 4 seconds. With 7 cells, you are there in 3 seconds. Hit reverse, and you will stop in 1/2 boat length vs. 2 lengths with the stock prop. This prop doesn't cavitate in reverse like the stock nylon prop does. The quicker response doesn't distract from its scale appearance.  PropDumBr08.jpg (16655 bytes)
Nice wave pattern. Just enough bow wake to create a twin set of bubbles behind the tug. More test data to follow.
Stock Tug 6 cells 7 cells
Amp Draw - Static Pull .50 Amp .63 Amp
Thrust - Static Pull 4.0 Ounces 5.0 Ounces
PropDumBr09.jpg (50167 bytes)