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

[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.

[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 . I am a fan of supporting things on bearings whenever possible, especially when bushings suck anyway .

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

[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 , if it was a snake, it would of bit me...... Lube on silicone .......

[ray schrauwen]

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