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.



.

[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

[Darin Jordan]

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


The aft bearing here is a flanged bearing. I haven't thought it through very far yet, so I'm not really sure what is available. If the bearings can't take thrust, then I'd probably come up with a system that used the same style bearing washer that we use at the couplers. Again, I haven't gone that route yet.

I put the step or taper in the drive dog to help prevent it from causing drag on the bearing should it make contact, but generally set the distance up so that the thrust is at the motor, and the drive-dog is just ALMOST touching the inner race.




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?



I would think so. I added two new holes to my strut, so I can use a top and bottom bolt if needed. Currently, I just use the one but it has a large diameter (about 3/4") tapered top flat washer to help spread the screw load out. Hasn't shifted yet...

[Darin Jordan]

Turned a few more nose-pieces this weekend for spares, and modified a second Speedmaster 21 strut as well.

Also, found some nice and straight .078" wire at the local Hobby shop and fabbed prepped t4 new wire-driveshafts. The Loctite is setting on them as I type this...

As you can tell... I like to have spare parts! Might as well make a few of each while you are already in the throws of making the parts in the first place.


Obviously, for something like this, you must reinforce the weak parts. In the case of the MG, Mystic, and BJ29, as we all know, the hatch can be an issue. SOOOOO... like many of the rest of you, I'm going to reinforce it.

Used some 5.5oz Carbon weave and fit it into place. Will laminate it in with some epoxy tonight.

[ron1950]

hey darin got a question about the 078 wire drive...did u solder them then jb weld or what ? how do u make those? second the hatch on my MG (one of the original first batch with right drive shafts and all that) has never even cracked and its taken some 50mph flips for sure....guess the first ones were just made better...thank goodness....

[Darin Jordan]

hey darin got a question about the 078 wire drive...did u solder them then jb weld or what ? how do u make those?

McMaster-Car "Precision Stainless Shaft", .1875 O.D., 7" Long, cut in half.
Use Lathe to drill with 1/16" drill as deep as it'll go.... approx. 0.900"
Follow up with .078" bit (5/64").

.078 Stainless Piano Wire shafts from K&S (look for the really straight ones).

Clean ends up with wet/dry sandpaper, clean well.

Clean out holes in shafts. Prime with Loctite Primer, blow dry.

Use sharp chissle to nick up the shaft a bit where it'll be bonded. Clean and prime.

Coat shaft with Loctite 603, fill hole with Loctite 603, slide together however you can, making sure it's seated (mine would "hydraulic" a bit), rotate and make sure it's seated.

Let set for a day or so. I drill some 3/16" holes in a block of wood and stand them upright, bring them in the house, and let them sit for a week or so, or however long.

Vola! .078" Wire-Drive shaft!



second the hatch on my MG (one of the original first batch with right drive shafts and all that) has never even cracked and its taken some 50mph flips for sure....guess the first ones were just made better...thank goodness....

I think you've been lucky! I haven't every broken one either, but I've seen enough broken to not take the chance!

Plus, this boat will hopefully see 80+mph... More likely, it'll flip trying... Not going to take any chances.

[ron1950]

wow that's more work then I want to put into a wiredrive...ill just buy mine from jeff lol

[Darin Jordan]

wow that's more work then I want to put into a wiredrive...ill just buy mine from jeff lol

Hahaha... It's a bit time consuming, but remember that the standard 2.5 or 2.75" long stubshaft won't work for my applications. I want to capture the stubshaft into the strut, so if the wire breaks, the propshaft stays put.

One of the benefits of owning a few hand-me-down tools like the 6" 1938 vintage Atlas Lathe that I inherrited from my Grandfather, who inherrited it from my GREAT Grandfather... :)

I'm guessing that, on special request, Jeff could probably custom make the stubs as well...

[Darin Jordan]

Almost there. Only thing left to do, aside from actually bolting in a power system, is to attached the stainless knife-blade SAW rudder I built for this. I'm still working on getting the two holes drilled in it for mounting. Destroyed two drill bits and a couple of Dremel carbide cutters trying to get through this material. Need to figure something out there, and definitely open to suggestions. Crazy hard stuff.

Wire drive setup turned out well. Bend is gentle and very natural and everything is so SMOOTH! Should work well.

[danielplace1962]

Darin,
You can try this. I have used the method successfully on several knife blades.
Get a carbide tipped masonry bit and change the way the tip is ground. You will see it is ground to a chisel type tip. Change it so the leading edge is sharp and the first to make contact so it can cut. Use a slow speed, good pressure and some oil.

Don't know your time frame to get it done. But these carbide bits will drill stainless.
http://www.cetoolsupply.com/servlet/the-DRILL-SALE/Categories

Be really careful especially if your using a drill press. Wrap the blade with cloth or something and duct tape.

The bob tail mod doesn't look bad at all. I like it.

[RandyatBBY]

Neet info Darin. I cut the back off of the Scat Cat 27 to race in in N2 also but I just had to cut off a inch. When I heard the rule change I had to do some think ing to get my boat to fit in to the rules.

I have been using 5/16X3/16X1/8 bearing in my struts for many years wit great success. The trick in in packing them and making sure the props are extremely balanced.

http://imageshack.us/a/img27/9683/0012so.jpg

[CornelP]

Darin, the easiest way for the blades is to just cut a slot with the Dremel cutting disk instead of drilling. I've done it a few times this year when I converted the rudders on my racing boats to cut down knives or SS palette knives (even better because of the bigger area and better price).

[gsbuickman]

Heya Darin, thanks for the build thread, there's a lot of great info here... I am interested in the wire drives, although I haven't added them to my arsenal yet. I understand you have a short piece of stuffing tube thru the bottom of the transom for the wire drive to pass thru, sealed with a piece of fuel line tubing. That's OK for a static display boat, but how is that functional ?. Won't the spinning drive pull the fuel line off the stuff tube, or melt due to friction ?.

Ill tell you a secret for drilling stainless that works great. Boeing developed a special thermal cutting / supercooling paste for drilling stainless called Boelube. I got a tub of it from western trailer b4 they went bankrupt in the housing crash. I use it For all my metal drilling & to dip my drill bits and pieces of hot metal I am working on in to cool them ...

[gsbuickman]

Sorry Darin, I forgot something :biggrin:. I am a fan of supporting things on bearings whenever possible, especially when bushings suck anyway :biggrin:.

Has anyone thought about or are you using ceramic swiss bearings to further cut down on drag, rolling resistance and because ceramic doesn't rust ?. Thanks:rockon2:

[Darin Jordan]

HeThat's OK for a static display boat, but how is that functional ?. Won't the spinning drive pull the fuel line off the stuff tube, or melt due to friction ?.


If you select the correct sized fuel tubing, it's not an issue... The tubing BARELY touches the wire, and it's lubed with oil/grease.

[gsbuickman]

Oh yeah, duh :doh: , if it was a snake, it would of bit me...... Lube on silicone .......:tt2:

[ray schrauwen]

I was thinking of this for N2 classes too.. Subbed...

[Darin Jordan]

FINALLY got the holes drilled in the Stainless knife-blade rudder. NOT a task to be taken for granted! I destroyed a couple of Titanium bits, broke some carbides, and generally floundered, until I finally was able to get through this stuff by slowly drilling with come carbide centering drills. Lube well!

I also decided to do something I've wanted to do for a while on these boats... I trimmed away a bunch of the extra height on the wood interior. Not a big fan of the wood inside in the first place (I actually lobbied for a colored carbon looking glass or otherwise something that looked more like a pan-car chassis for inside there).

Trimming this away takes away a tiny bit of weight, but, more importantly, makes it easier to get batteries in and out and makes it easier to route the battery wires, etc. Cleans it up a bit, I think.

[RandyatBBY]

I do not know if you use my tips, But hear is a good one on drilling stainless steel. I do it all the time. Always use the slowest speed you can on the motor set up, Make sure the drill bit is sharp. If you can see the cutting edge it is dull. I always take out the crown on the heel. Do not push hard on the bit. Freeze the tip with a aerosol can like WD-40 offten or at the start of a crunching noise. Try to keep the heat as low as possible on the SS, It hardens with heat and becomes impossible to drill the hole.

[ray schrauwen]

..or get a a better bit: DRILL (http://www.youtube.com/watch?v=dTGB9Od0ND0)

[ray schrauwen]

FINALLY got the holes drilled in the Stainless knife-blade rudder. NOT a task to be taken for granted! I destroyed a couple of Titanium bits, broke some carbides, and generally floundered, until I finally was able to get through this stuff by slowly drilling with come carbide centering drills. Lube well!

I also decided to do something I've wanted to do for a while on these boats... I trimmed away a bunch of the extra height on the wood interior. Not a big fan of the wood inside in the first place (I actually lobbied for a colored carbon looking glass or otherwise something that looked more like a pan-car chassis for inside there).

Trimming this away takes away a tiny bit of weight, but, more importantly, makes it easier to get batteries in and out and makes it easier to route the battery wires, etc. Cleans it up a bit, I think.

Can't see that skeg strut in that pic. C'mon Darin, show us the skeg! ;)

[Fella1340]

Geat information, I will try this out in the future. I really like the idea of transferring the
load off the motor and onto the strut. I wonder why this isn't a more widely used
setup?

[Darin Jordan]

Can't see that skeg strut in that pic. C'mon Darin, show us the skeg! ;)

I tried a skeg'd strut on my Miss G when I ran it at the 2012 Nats in P-Ltd Cat and Offshore. By the time I got the boat dialed in, only about 1/8" of the skeg was left (I trimmed it down a bit at a time).

The boat REALLY turns well, but scrubs sooooooo much speed with even the slightest turn of the rudder that it simply wasn't worth it. I have NEVER had an issue making one of these cats turn. I'm usually pretty surprised to hear that others do. These boats turn HARD. I think it's a matter of driving technique. You have to drive them sort of like a tunnel as far as approaching the turn-in... After that, throttle on and go.

Better yet... "pivot turn" them.... I aim right for the buoy, and then just make an almost square corner. Works well.... right up until you grab an outside sponson and barrel roll it... :doh:

[mannytx1]

Hi ,Darin

Thanks, I cut the transom and strut closer to the transom / sponsor is more stable catamaran
111222111223111224
111235

[Darin Jordan]

Well... after establishing the initial NAMBA N2-Cat SAW record with this boat (65.XXmph) last November, I went out for another attempt and, due to what we found out was a flaw in a Beta release of the ESC Firmware (had just updated everything prior to the weekend), the ESC burned up and took the boat out for the weekend.

I was going to just shelve it, but decided that maybe I'll try to do some resurrecting.

After some time with some Denatured Alcohol, it's actually cleaning up pretty well. The burn was so bad that the "brown/black goo" actually leaked out of the nose of the hull, out a crack in the deck to tunnel area.

Not going to be able to get this entirely cleaned up, but I think I can get it pretty good with a little more time.

Here are the results thus far...

[ray schrauwen]

Well, I'm known as Mr.Kapow here in Canada so don't feel too bad Darin. Looks nice and clean now! Tooth brush helps.

May I ask what brand of esc it was?

[Shooter]

Oh No!!! Sorry to hear about the 'electrical event'.

So, apparently that 'thrust at the strut' method is working, huh? .....Sounds like you set a record with it?

[Darin Jordan]

Oh No!!! Sorry to hear about the 'electrical event'.

So, apparently that 'thrust at the strut' method is working, huh? .....Sounds like you set a record with it?

I did, and the boat worked OK... For SAW use, this hull is pretty heavy and certainly not ideal, but it was FUN! I had airdams on the tunnel AND on the top of the deck to keep the nose down. Those kind of band-aides aren't the most efficient way down the course, but seeing this fly by at 65mph plus on 2S was pretty cool...

Just a fun project. I just can't leave it for the scrap heap, especially since it's not really that far gone... Just smelly... :flashfire:

[ray schrauwen]

Would it not make a nice N2 offshore hull?

[Darin Jordan]

Would it not make a nice N2 offshore hull?

It does...

It also made a nice N2-Hydro National Championship hull... :tiphat: