51 inch Mystic Style Mono Build

[Rocstar]

In over 20 years of doing boats I have never wore out a drive that wasn't related to where it goes into the collet or from rust. Tunnel hulls are a different story with there massive bends.
I had a sport hydro that had a very strait shot and it would vibrate like crazy on the bench when you spun it up. On my next build I put a slight S bend and it was smooth as can be. That was over 15 years ago and I never worried about S bends again. I only brought this up because I thought it was crazy for Joel to mill out his motor mounts just to avoid an S bend.

Mark

Joel won't be milling anything....Craigen would be. And for some, milling a small part is a simple process. Again, I think an S bend will work fine, I just don't use them unless necessary. In the 15 or so boats I've built in the last two years (twins, singles, big and small), I've had to do it once.....and I may have to on an N-cat I'm building now...It is what it is.

[Andrewc]

Hi all Interesting information.

Having listened to what people are saying I have decided to move the motors a bit further from the transom to reduce the sharpness of the bend. At around 150mm the bend seems soft enough to me. Anyone any thoughts on how deep I should set the rudder?

Thanks all.

[Andrewc]

Hi all. I assume I should have the trim tabs as close to the stingers as possible?

Cheers

[Fella1340]

I have spent a lot of time looking at every big single and twin motor mono out there as you know I am building the same boat with a single motor. the bend you are taking about is only 15mm and seems minor compared to some of the other big twin monos I have looked at. Your stinger spacing is also on the narrow side compared to similar builds. They have been from 90mm down to 70mm so you appear to be in good shape with where you are now. If you can find a machine shop in Spain that can do the job that's great, otherwise just go with what you got. You can always ship them over to me for machining if you like, postal time may be a little long though:) Don't let yourself get to hung up on this.

[Andrewc]

Hi. The motor mounts are currently being milled so if he understood my Spanish the mount will now have 80mm centres and the stingers at 70mm. This will give me just 5mm of bend on the tubes which I think will give me the best of both worlds.

[Fella1340]

Should be an ideal setup!

[iridebikes247]

really nice setup. Curious what cell count will you be running and props? I'm curious how a big mono runs with 3 vs 2 blade props. I imagine 8s1p per motor with x450 3 blades would be cool.

[Fella1340]

I know he plans on running 8s and would be happy to hear any suggestions for prop size.

[Fella1340]

Craigen, did you get anywhere on what the correct depth of rudder should be?

[Andrewc]

Craigen, did you get anywhere on what the correct depth of rudder should be?

Nope, nothing on that front yet.

[Skullcracken]

[QUOTE=Andrewc;550189]I finally purchased this 51 inch Mystic style mono hull from a company in China as a 50th birthday present yo myself. I have no idea why as I have no clue as to what I am doing, but it is enjoyable.

It is a fibre glass hull which I have strengthened throughout with carbon fibre and a 4mm marine ply strengthener to the transom. I have also added a bulkhead toward the front behind which I added floatation in the likely event I should crash it.DSC03767.JPGDSC03806.JPGDSC03794.JPGDSC03805.JPGDSC03808.JPG

Really struggling to get these pictures attached properly but hope this gives people an idea as to what I am doing.

I have purchased:

2 x Leopard 5692 1090Kv Motors

2 x Hifei 200amp HV Esc

2 x Contra Rotating prop shafts

2 x Trim tabs

2 x Turn Fins

2 x Stingers

1 x Rudder

I am about to start positioning the hard ware to the transom and need some advice:

How far below the keel should the rudder project?

Should the stingers be as close together as possible or as far apart as possible?

Should the props spin inwards or outwards?

Where on the length of the boat should I aim to have the centre of gravity?

Hope someone can help!!!!

Cheers

Craigen[/QUOTE

Man, what some guys think of as "I have no idea what I'm doing" is comical to me. There are newbies who don't know you're supposed to grease the shafts. That's not knowing what you're doing. You seem to be off to a good start. I don't think that is a Mystic theme mono. (Not that it matters). It looks similar to the China version of a fountain p1
fountain p1.jpg

[Andrewc]

Finally got the brass shafts fitted. Had several attempts at making the bends but with a bit of practice and a bit of wasted brass I am quite pleased with the results. Found a bit of old rubber tube from a tap fitting which I have now placed over the brass tube for aesthetics. Quite please with the overall results. The shaft supports were made from marine ply and then veneered over with some thin carbon fibre strip I had left over. Again only for aesthetics.

Anyone any thoughts on rudder depth as this is the next bit? ThanksDSC03862.JPGDSC03863.JPGDSC03864.JPGDSC03865.JPGDSC03866.JPG

[Andrewc]

Rudder installed, stingers installed and flexis cut to length. Quite pleased with the result. Messing around with some ideas for the Esc´s which might also hide some of the cables and water pipes DSC03871.JPGDSC03872.JPGDSC03874.JPGDSC03875.JPGDSC03875.JPGDSC03876.JPG

[Fella1340]

Looking great Craigen. I couldn't get any info on rudder depth on a separate post I started. Looks like we are on our own! I was wondering if it might be a good idea to put a motor support in the middle. Perhaps a cut down support from the left over motor mounts. Just a thought as there is a lot of torque there. I like the direction your going with the esc's, looks like it could be a really neat and tidy idea.

[Andrewc]

Sort of agree with what you say regarding additional support for the motor mounts but I am more concerned with the forces on the shaft support. I think, and may well be wrong that the motors will be contra rotating and therefore the forces should balance each other?

Anyone any thoughts?

Thanks