Darin's Pro Boat Mystic "29 Minus-Two"

[Darin Jordan]

Thought I'd show some pics of the boat I put together to run N2-Offshore at the Nats... and also what I ended up using to run, race, and WIN, N2-Hydro...

Kind of a fun project, and it worked out really well. Again, the smaller wheel and higher KV seemed to be the trick to keeping these from tripping in the turns. The torque from the huge wheel needed to run the Low KV setup seemed to upset the handling just enough to torque roll the boat in the turns.

Otherwise, it had more than adequate speed for N2-Offshore. The boat actually worked very well in the corners too. I recall a heat against Lenny Blake with his Titan 29 where I held him off for many laps, until it just suddenly tripped up and wound up upside down. If not for that, he wouldn't have been able to catch me. We'll have to work on that.

Transom is made from 3-layers of vacuum bagged carbon fiber that I laid up, and the hardware is stock Impulse 31 hardware. Stock flex shaft only had to be shortened 1/4" to make it fit.

After the transom was chopped, I still had to remove 1/2", so I filled the sponson tips with epoxy mixed with milled fiber, and just sanded them down to size. I didn't actually have to even paint them orange... I did most of this without really damaging most of the visible paint. Rather than try to touch up the white, however, I thought the orange would look pretty cool.

Power system for N2 Offshore was a Neu 1515 1.5D (2700KV). Initial testing was done with a 1512 1.5D (3200KV), but I had better speed with the 1515 @ 2700KV and a HUGE wheel... X452/3, with some work done. Average Amps were around 115...

For N2-Hydro, I borrowed a 1515 0.5Y from Tyler Garrard and spun a 440/3, then a 537/3, then back to a 440/3 with some pitch added...

[Darin Jordan]

A few more shots...

[ron1950]

i like the way u think ...lol...very nice

[Fluid]

I'm glad to hear this boat worked out so well for you Darin. I remember the pics you sent of the 'surgery', and I remember thinking "why not?" Why not indeed.



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[Brushless55]

This looks realy cool!

[Rumdog]

Good thinking, man! I like it, a lot. Does it handle much different without the transon overhang? (lift wise)

[Darin Jordan]

Good thinking, man! I like it, a lot. Does it handle much different without the transon overhang? (lift wise)

I didn't really notice any real difference in handling. If one watches closely, there MAY be a little less water hitting the hull on it's escape from under the sponsons, but I'd have to watch video to see for sure.

I do contend that there might be something going on in the rudder area that is causing some unnecessary water spray (which = drag)... I need to find out where that is coming from and reduce it. Might take this setup and put some SpeedMaster or ??? hardware on it, or at least the rudder, and see if it improves the efficiency.

For a setup using almost all stock pieces, it worked great and was a blast to drive. Again, higher KV with smaller prop seemed to work best for overall performance. the 1500KV motor with a HUGE prop was VERY fast, however... When I tested it on 4S, that is...

[Hotrods]

Accutech Hardware is thinner, faster, and stronger....fyi....Look at their "A" small assembly. I think you'll be impressed

I didn't really notice any real difference in handling. If one watches closely, there MAY be a little less water hitting the hull on it's escape from under the sponsons, but I'd have to watch video to see for sure.

I do contend that there might be something going on in the rudder area that is causing some unnecessary water spray (which = drag)... I need to find out where that is coming from and reduce it. Might take this setup and put some SpeedMaster or ??? hardware on it, or at least the rudder, and see if it improves the efficiency.

For a setup using almost all stock pieces, it worked great and was a blast to drive. Again, higher KV with smaller prop seemed to work best for overall performance. the 1500KV motor with a HUGE prop was VERY fast, however... When I tested it on 4S, that is...

[tryinotocrash]

Nice work. Could name it Miss stumpy :-) Thanks for sharing.

[Darin Jordan]

Thought I'd post an update. I decided to pull this boat off the shelf and do a few prep mods, this time with some serious "speed" use in mind. It worked really well with full N2-Power... I think I want to see what it'll do with SAW N2-power!

I did some cleanup to the ride pads to fix some scuffs and chips from the racing since the 2012 Nats, and go that part back into primer. Also did some R&D tweaks to the ride pads, but I won't highlight those here. Probably more responsible to find out if they actually WORK first!

In the meantime, I wanted to beef up the driveline, so I decided to see if I could fit a .078" wiredrive. Going to build a stub-shaft-captured style strut as well.

I found that I COULD just run the .078" wire in the stock strut, up the factory stuffing tube, without any adverse bends. Seemed to be smooth and quite a natural fit.

However, I wanted to run this as exposed wire to eliminate any potential drag or lift from the factory stuffing tube in the tunnel.

I'm not always as neat and clean with this as some of you, so please forgive the rough cutting. I was in a little bit of a hurry.

First thing was to trim around the fiberglass enclosing the stuffing tube in the tunnel. Used a Dremel with a cutoff wheel to do this.

Once that was broken loose, I cut the stuffing tube inside the hull, near the wood platform (for the ESC) and then grabbed the inside piece of brass with pliers and crushed it a tad to break it free of the epoxy. Worked with it a bit and it pulled out. A quick twisting of the outside piece freed it from the hull as well.

After cleaning up the area, I trimmed the hole a bit to provide plenty of room to put the wire/stuffing tube assembly so it would lay in naturally.

[Darin Jordan]

After the hole through the hull was prepped and everything cleaned up, I took some brass material (sorry, I'll get the sizes tonight. Forgot to jot down) that fit nicely over the .078" shaft (likely 5/64" you suppose?), and the next size up, and cut a length of each that would allow the shaft to extend to the motor, and about an inch or so outside the hull.

The outer piece will be epoxied into the hull. The inner will slide inside and be tacked in place with either some silicone or loctite or ??? This piece is replaceable/removable, just in case. Plus the larger outer piece gives the smaller inner better support.

I trimmed the wire to fit fully into the hull, engaging the motor coupler and the strut, so that the setup will have a natural bend between the strut and the motor.

I mixed some epoxy with some milled fiber (milled up fiberglass) and filled up the cutout on the outside. I then taped over this carefully with some electrical tape, and turned the hull right-side up.

I mixed up some more epoxy and cut a piece of carbon-fiber. I filled in the slot on the top with a mixture of epoxy and milled fiber, then placed the carbon over the top and epoxied it in place. This all should provide a nice rigit mounting.

I tried to leave room at the top of the stuffing tube to place a piece of fuel tubing to act as a water seal.

Once this is dried, I will be trimming off the outside piece to be just a tad beyond flush with the hull tunnel.

I will address the strut shortly. Still working on that part.

[SloHD]

So a wire drive is stronger than a flex shaft? And you don't need tubing all the way to the strut? Sorry for the newbie questions. I really like what you have done so far, and I like the impulse hardware.

[Darin Jordan]

So a wire drive is stronger than a flex shaft? And you don't need tubing all the way to the strut? Sorry for the newbie questions. I really like what you have done so far, and I like the impulse hardware.

Wire drives have less "wind-up" than flex. Whether it's stronger or not I'm not sure, but a wire, if (BIG IF) properly installed will have less drag all around. I would suggest that it DOES need to be supported for high-frequency use (daily bashing, etc.), but for a race boat, especially a SAW or 2-Lap Time-Trial setup, where you are trying to extract every last RPM and watt, the less drag, the better. I've had pretty good luck with running them unsupported, but I'm pretty careful installing them, and have only been using them on pretty low-powered apps. This will be the highest powered application I've tried this on. I think it should work fine, however...

[Darin Jordan]

I finished modifying a strut for use on this boat.

Started with a Speedmaster 21 sized strut. Removed some of the nose, and used my mill to cut a small "step" on forward portion of the right side of the strut, to allow it to nicely fit over the slight "step" in the IM31 strut bracket.

Also milled the bore to hold some 3/16" ID stainless bearings.

Stub shaft still needs to have the threads added for the prop nut, but was drilled for .078" wire on my lathe. Pretty long and time-consuming process to do this in stainless, but the holes turned out prefectly true, so the shafts should hold up for some time. I did 4 stubs total. I love spare parts, especially when I can make them myself.

Stub Shaft source material are from McMaster-Carr. These are "Precision Stainless Shafts" and were ordered as 3/16" O.D. x 7" long. I used a cutoff wheel to cut the 7" shaft into a pair of 3.5" stubs, cleaned up the ends in my disc sander, then proceeding with the lathe work. Just need to get a 10-32 Die so I can thread them for prop nuts.

These stick out of the front of the strut about 3/8" or so, and will be captured by nose-cone pieces that I lathed up from some aluminum stock. Two set-screws in the nose-cone. The leading part of the hole in the cone was drilled to 3/32", so it provides just a bit of clearance around the wire and does not touch. This allows the wire to bend/curve all the way to the front of the stubshaft.

One more step that I will do that isn't shown is to lathe a small "step" on the leading edge of the drive-dog, so, if desired, I can take the thrust at the strut by sliding it up against the flanged bearing and only have it contact the center race. Did this on my little boats and it works very well.

[Shooter]

Wow. Great job. Drilling a long, small diam. hole ain't easy in stainless!

Moving the thrust to the strut is something I've thought about for years, but never really dabbled with it.....mostly because it would require some sort of slip fit flex (square drive) -OR- wire drive, like you are using.

A few questions, if you don't mind.....

1. What type of thrust bearing @ the strut would you consider? Teflon, like the older outboards, or ball bearing?

2. Do you think the standard 1 bolt strut mount will need to be beefed up (i.e. two bolts) if we are moving the thrust to the strut?

Thanks,
Pete