Scat Cat First run

[Jeff Wohlt]

Ran my new Scat Cat with the 290/20/4 this weekend. I popped a 207d but it must have been ready to go anyway. I stuck in an RC Hydro ESC and no problems and cool when done.

I also popped a shottky diode on the plett...what is that caused from? Now I know what those smell like...a welding shop!! I guess it must have happend yesterday since I do remember smelling it but today but it ran fine today with it cracked.

Here is my question: I am running a X438 with this motor and I feel it is pulling a bit much and not unwinding like it should. Only getting a couple minute run out of some old 1700 cells.

How far should I bring the strut up? I have it above the bottom hull pads but wonder if I should raise it until I get some rooster tail or what. I think it may run better letting it spin harder.

It is riding with a good attitude on the water...trimmed nicely as far as on the water.

[Andrewg]

Jeff

the Schottkys can pop because:

1. too much current (ie the spikes are big and they cant cope); or
2. they are put on with polarity reversed. Correct orientation is
with silver stripe at the positive/red terminal.

I think you are right about overpropping. The 290/20 likes 632's and 435's with 8 cells if I remember correctly. The additional current draw would explain why the Schottky popped.

Jay is the expert on setting these up. However, I believe he starts the strut bottom level or 1/8" shallower than the running surface of the sponsons

[Dan Chase]

Jeff,

I agree with Andrew, I think you are way over proped. An x632 should work real well with that setup.

[Jeff Wohlt]

Thanks for the input.

I just thought getting the prop out of the water would also help. I also run 3/16" shaft so I need to stay with that.

After running a couple more times, I find that the motor is hardly warm, ESC is the same so not really sure.

I think the 1700 cells I have are about gone as well. I get maybe a couple minute run befor they dump.

Chris Fine and Jay Turner thought the 438 would be a good start. Looks as big as my Prather 215.

Is the prop buried too deep? I should get some rooster tail...No?

The prop shaft and strut is a good 3/16 above the hull bottom. I have moved it up but have not run it again. I also have it running with most of the hull out at least half way back. I figure the strut may need to be higher due to the weight.

Thanks... for the info.

[Jay Turner]

I think there is room to raise the prop; I often run mine 1/4+" above the bottom of the sponsons. A lot depends on how high you fly the hull - the higher the nose, the deeper the prop runs.

Going too high will result in prop blow-out in rough race water or turns, and it can cause fishtailing on the straights. But if the motor isn't hot then the prop is probably not too large for your setup. In this case the motor is winding up as it should. However you may find that with better cells the motor will draw more amps and exhibit more loaded characteristics ( heat ). When that happens it is a different ball game. You can cut some blade area or diameter off the x438 to reduce the load - the pitch on an x632 is about the same as that on an x438.

BTW the Prather 215 is roughly equivalent to an Octura x640 - quite a bit more prop than the x438!

[Jeff Wohlt]

Thank you! I have raised the strut and will try it out. I can remove a bit from the blade but also wonder about removing the tongue on it a bit.

All else seems fine as far as heat and ESC. I think as the boat was trimmed to run nose a bit higher that it was indeed sticking the prop down deeper. I also run the strut almost with no angle in the strut...maybe a tad and my Cg is aorund 6-7" on the cat.

Thanks....I should be seing a nice low rooster tail I would think...I get nothing...it is fast but for short duration...maybe a few fast laps.

[Randy Naylor]

Jeff Hi
I would strongly sugest changing to the X632 your speeds will inceese and the run time will go up and the heat down. Heat is the killer of magnuts.
You know what I say? Try it you will like it!

[Jeff Wohlt]

Thanks, Randy. My problem is that I just don't have enough props in my inventory.

I think for now on I am going to try some carbon props on new boats until I get close and then buy, balance, sharpen, polish and all that for the OCtura props.

[Mathieu]

Do you know Graupner provide props with pitch from 0.85 to 1.6.

I think this is the best way to setup the trans. Then by the right metal prop and MAGIC your boat faster than ever...

Waiting for news !!!

See you

[Mathieu]

For those who doesn't want to download it.

http://www.multimania.com/kd32/tmp/prop1.jpg

http://www.multimania.com/kd32/tmp/prop2.jpg

http://www.multimania.com/kd32/tmp/prop3.jpg

http://www.multimania.com/kd32/tmp/prop4.jpg

http://www.multimania.com/kd32/tmp/prop5.jpg

http://www.multimania.com/kd32/tmp/prop6.jpg

If you want better quality, let me know, I'll do it.

[Jeff Wohlt]

Thanks...I think most of us have seen these but the real problem is getting them without waiting 8 weeks from Hobby Lobby. The will order them as long as we provide the part number.

I could only see a few that I would be interested in...alot of these are 4mm prop shafts...correct?

Thanks for the pics.