In my review of the 403 I mentioned that ideally the prop could be a few inches deeper into the water than the maximum mounting adjustments allow. This would help with a couple of issues:
- Reduce or eliminate cavitation at max rpms for even greater speeds
- Help prevent the prop from coming out of the water in turbulent conditions
I asked Torqeedo if a longer prop shaft was available. They replied no. So I originally thought of replacing the prop shaft myself. This presented a few significant problems: it probably would have voided the warranty, and the wiring going to the motor would probably need to be extended which would have been difficult. So I abandoned this idea.
Over the winter I thought of several ways to lower the motor a few inches but I didn't like any of them because they were either too difficult or too kludgy or both. Finally it dawned on me how to do it. Using a couple of parts available from Torqeedo shown below, I could simply cut the existing horizontal shaft as close as possible to where it mounts to the vertical shaft, mount a Clamp Base to each cut end, and then attach an easily fabricated aluminum plate of whatever length I desired between them to lower the prop as much as I wanted. Unlike the prop shaft which contains wiring, the horizontal shaft is just a simple 44mm (1.75") aluminum tube. You could either purchase another horizontal shaft directly from Torqeedo for $23 or buy your own aluminum tube if you didn't want to cut the original.
Clamp Base UL Item number 069-00015
Fortunately Torqeedo sells the Clamp base right on their web site
right here so I ordered the parts yesterday. When they arrive I'll fabricate the plate out of a piece of aluminum and mount the motor. If this proves successful I'll post the results here.
This may take me a few weeks to do since I'm also very busy at work and with other projects. So I wanted to offer a preview of this now since boating season in the US North is getting underway. Anyone else who may wish to take it upon themselves to try this (at your own risk) might not want to wait until I'm finished. I'm reasonably sure that it'll work but I can't say for certain until I rig it up and test it.
So stay tuned and I'll let you know what happens along with photos if successful. I think this relatively easy modification will reduce or eliminate cavitation that occurs at the highest rpms which may result in even greater speeds, so it's worth a try.
I should note that this is only a performance modification to try and get a bit more speed. The 403 works nearly perfectly out of the box on the TI and this modification is not necessary for normal operation. But I'm a tinkerer and enjoy this kind of thing. If you're the same way you'll understand. It's my goal to make the 403/TI application as optimal as possible.