Mystic 138 First Rc Boat assembly.

[grsboats]

Looking nice!

[nata2run]

Nice looking build, I'm a bit curious about the flex drive to motor setup. You mention you used a piece of CF rod to align the motors. Have you done a test with the actual 1/4' cable mounted to the prop shaft to see if it spins freely? In my experience there is always a nice curve to the cable coming from the drives to motor-collet.

[sebasoakley]

Thanks for your comment.
Yes first I mount the carbon rod for check and adjust straight as possible and after flex shaft direct to the drives and runs very smoothly...
Today I mount the flex shafts. Please any body can check if its right?.
Thanks very much and regards.

[sebasoakley]

[nata2run]

I would not recommend using square flex ends, but rather using a proper collet from MBP or similar. The gap between the tube and collet should also be a bit less than what you are showing. (10mm is good) I have attached a couple of pictures of what a setup could look like (Just an example, not a must) to get an idea of how I built my MHZ138. Please have a look here http://forums.offshoreelectrics.com/...-McLaren-Theme There are a couple of steps showing how I worked it out. I'm not telling you how you must do it, but I notice you have done a couple of things, then asking the forum "did I do that right?" it would be best if you don't drill any holes or glue anything until you are 100% happy with what you are doing. :-) I'm not an expert, by no means! But I also started once, and made mistakes. Working on these boats can be costly, so you don't want to make too many mistakes. Its best to take your time and work it out slowly. What you have already done WILL WORK, and your boat will run. But it looks like you have the skills to make it even better. So you might as well :-)

both flexes.jpgFlex cable 1.jpgStuffing tube brass.jpg

[iridebikes247]

Found this picture of the 114, hope it helps.

I thought the same thing as Kent. I have no experience with the square flex, but have always used round cables with the MBP collets Kent rec.

When installing the stuffing tube I like to use CA glue to tack the stuffing tube holder in place, then after scuffing up the area (again) use epoxy. I think the stuffing tube is very important, improper alignment or too much flex exposed can create big problems.

Motor mounts look good epoxied in, coming out good.

[TheShaddix]

What is the main reason you guys don't want to leave much space between the stuffing tube and the collet? Vibration of the flex? Or water leaks due to being too low in regard to water line? Everyone says it's important or it'll cause issues, but no one really says exactly what those are.

And why is it better to have such short stuffing tubes? Is there a benefit to that?

[nata2run]

If the stuffing tube is very close to the collet and proper aligned, its less likely to snap. If its spaced far apart, the cable can "wobble" under high rpm and snap. leaving a lot of exposed flex cable can also be a good source for getting stuff caught. cable, sponge, paper towel and so on. water will find its way up no matter what :). But vibration causing snap, or getting things caught in a spinning cable would have to be the major reasons.

[iridebikes247]

I've never made a stuffing tube short because of concern about cable strength. I think "whip," can become a problem when cables get really long, but most cables are cut to a reasonable length in the mystics, hprs. A lot of people mount the motors in the back since motors of course will be fixed in place, so additional leeway with CG is never a bad thing. I really don't think a flex will break if the stuffing tube is 3 inches vs 4.

It definitely comes down to preference too, some people mount motors pretty far up if they're confident they know how the hull will perform at speed.

[sebasoakley]

Sincerely thank you very much everyone for the comments.
I think that I'll ask for brass tubes again to make them longer.
Thanks again.

[Crash]

Sick build !

[TheShaddix]

Thanks for explaining! Now I understand. The wobble is definitely a good enough reason to not have a gap. My only hesitation was that removing the motors would take longer if the collets were still on leaving less space for the allen key to work. I'm sure that in this 138 it's not even a problem!

[sebasoakley]

Nata2Run, please why you dont recommend use a square end flex shaft?. Im making longer flex shafts cover as the photos you show me, thanks for that.
Thanks very much everybody for your commnets, them are helping me a lot.

[nata2run]

Nata2Run, please why you dont recommend use a square end flex shaft?. Im making longer flex shafts cover as the photos you show me, thanks for that.
Thanks very much everybody for your commnets, them are helping me a lot.

I wouldn't recommend purely because of the potential high rpm you can spin. It's not common in a setup like yours to use square shaft ends. Like I nentioned before, what you are doing will work, but there are better ways. A strong true spinning collet, with a good grip on the shaft is much preferred over alternative systems.

[sebasoakley]

Hi, thanks very much for your replys.
Please someone knows where should be located the gravity center of this hull?.
Thanks very much.