That stinks.. Sorry to hear that.
I've come to the conclusion after doing some more reading from Honks thread and Jeremy's from boatdesign.net that I am obviously using too much prop. As Torqeedo mentioned a large prop at slower RPM is more efficient than a high rpm and small prop. I can't wrap my brain around that though, should work just as well. Kind of like the muscle car vs. the japanese high rpm. They each have their own merits. I know the jet is less efficient, but they use a 4 inch prop (ok impeller) at 3-6k rpm, Why can't we just a 4 inch prop on a direct drive at 3-6k rpm? Does a prop like that exist? My RC boat has a small prop that spins at 28k rpm. That works quite well! I don't get cavitation or efficiency issues. Also, bench testing and water testing these things are totally different and have made me believe things would work better than they did on the water. The props you (blisspacket) were using look similar in size to the Torqeedo - and the Torqeedo was designed for 1300 rpm. Pushing them faster than that is what is going to blow things. I can't recall your kv on the motors though. Just like gearing in your car, you are trying to start out in 5th gear.
I did get some more testing in on today. I was at the lake anyway to try out a new paddle board for the kids. I put on the Machete prop and was using the 80100 motor. This was on a small 8ft board. On 6s I managed to get on plane and ride at a decent clip. The board had too little volume to keep me floating well though. My ghetto mount didn't allow me to try and stand and it was difficult to turn laying down. Motor never seemed to go out of sync, even at full throttle. My wattmeter showed 110a and 2400 watts. Motor was cool and esc was too. I got excited and grabbed another battery to run on 12s. This time the speed was higher, but it would go out of sync sometimes on full throttle. After a short test - I checked the gear. ESC was hot as ever. I didn't want to run it much longer as it would melt everything in the box and I don't want to buy another HV ESC. The meter showed 3600 watts this time at 91 amps.
Again, I'm left with a feeling I can get it worked out, but not quite close enough. Maybe try it on 8s - with the longer board. I still won't be where I need speed wise, but if it was rideable... I'm debating whether to plunk down money on the neugart gearbox, go back to working on the jet unit I have, wait on Aquilla or still monkey with the Machete prop. I'm wondering If I can heat that prop up and give it a higher pitch, or shave some surface area off. Reading Jeremy's thread about using RC airplane props had me looking at what size prop fits on the 80100 motor. I couldn't seem to find any on hobbyking that fit the 12mm shaft. Jeremy mentioned that airplane props are actually the most efficient (I should saw very, not most) in his thread. What size prop was this motor made for? I have some 1045 slow fly props, but they are made for a 3.17mm shaft. I can't imagine the length of something for the 80100 motor. Plus those 1045 props are made for 12k rpm.
Louiss - how did you get a speed measurement? I am sure I way overestimate how fast I'm going.
eekim13 - Good luck on your project. Any new ideas or attempts are appreciated. I did a search for the unit and came up with this:
http://www.ebay.com/itm/RC-Boat-Shi...40-Motor-/271547454999?_trksid=p2054897.l4275
A much cheaper option if you are going to go that route. I think Wavejet uses something similar. They have dual jets - but don't go fast enough - just help you into the wave. Might be good for what you want. I believe the 80100 motor with Machete prop would do something similar speed wise. You don't have the safety and ground clearance of the jet with a prop. I'm curious why the unit says 540 motor - if it is meant for a brushed 540 motor it won't last long. You will be putting way more power into than that.
Last thing, this would already work if I only weighed 100 lbs. Time to start jenny craig
