Another Hare-Brained Idea

[NativePaul]

While Oliver does have molds that are decades old, he does also make a new boat every year, so while they are mostly the same, his list is slowly growing.

Your such a tease, he has 4x <500mm stepped monos, which one did you get? I am guessing Mini King Cobra.

[Dr. Jet]

...

You're such a tease, .....

Who me??

[Dr. Jet]

One issue I faced was finding the proper rudder for a mini. There is this one that I've used countless times (https://www.offshoreelectrics.com/pr...prod=ose-80048), but its short length would require mounting it rather low on the transom. Additionally, I don't like where the pushrod connects; it's not in the plane of the pivot and as such has some "differential" throw built in. Another option is this one (https://www.offshoreelectrics.com/pr...prod=ose-80047). The pushrod end is in the plane of the pivot, AND its longer length allows it to be placed higher on the transom, but wait!....... That bracket is WAY too long and has internal attachments that just won't work.

What to do?

Swap mounting brackets of course!!

Oliver included a piece of Delrin with the hull that was machined to the proper angle to match the sloping transom. I machined this Delrin block down to fit the bracket dimensions and all is good now.

[Dr. Jet]

I'm using one of Oliver's straight shaft assemblies. I have these on my Geckos and they work extremely well; shaft alignment issues are non-existent. He has ball bearing models as well, but this particular one has a 4mm brass tube with a short 2mm I.D. brass bushing at the propeller end. I have a bunch of 2mm x 5mm ball bearings that I use in the Geckos, so I'm thinking of reaming the motor mount out to fit a 6mm brass tube and use a couple of ball bearings to support the shaft. I like the idea of a center bearing support as well, but I make sure it's not EXACTLY in the middle as it would fall on a vibrational node if I did. They seem to run much smoother if the center bearing is a bit off-center, if you get my drift. .

[Dr. Jet]

I've mounted the rudder to the transom and have made an opening for the pushrod. In this build, I'm going to use the conventional pushrod and bellows arrangement for the rudder linkage. Now I have to figure out where and how I'm going to mount the servo.

[Dr. Jet]

Made the servo mount from a scrap of carbon fiber sheet. The epoxy is cooking off now, I'll check it in the morning.....

[NativePaul]

Snap. I also found the 50mm rudders to be insufficient for Minis, while the 62mm are goldilocks in blade size, but too long in the mount.

This is on my current Mini Hydro oval boat.
20200405_131908.jpg

[Dr. Jet]

Great minds think alike.....

[Dr. Jet]

I've mounted the servo and constructed the rudder linkage. I had to put a slight bend in the pushrod to make it all work, but that's OK, that's just one of the benefits of working with minis. With a 1/8 scale boat, finding a spot for the ESC is a no-brainer. On a boat with a working area that is only slightly larger than the palm of your hand, it becomes a bit more problematic.

[Dr. Jet]

The Secret Revealed!!

I've been pulling Native Paul's chain with this project by not revealing what it is. I thought I may have given enough clues already to determine which of Oliver's hulls I am bashing into submission:

1. Whimsical appearance (that's a dead give-away).
2. Under 500mm.
3. Stepped mono.
4. Sloping transom.
5. Flood chamber.

So for those of you still wondering, here are some photos with more to come in following posts.

[Dr. Jet]

More Revelations

More progress photos. Flood chamber details and hatch stiffening.

[Dr. Jet]

Even More

Even more progress photos.

[Dr. Jet]

One of the thoughts rambling around in my head is the cooling system. As you can see, there's not a whole lot of room in this hull for miles of hoses and tubing, so I have to plan things as I go. The hull inlet tube will be somewhere near the turn fin. Then, the hose will go in the "wing" behind the servo and curve into the starboard side of the aluminum cooling block I've attached to one of those cheap 30A ESCs (see previous photo). From there it will go to the motor jacket, but then what?

I don't want/need a bunch of extra length in the system, and since the motor is so close to the front end of the flood chamber; why not vent the cooling water INTO the chamber?

It shortens the hose/tubing run, and leaves a cleaner exterior.

[Dr. Jet]

Driveshaft/motor mount installed, cooling inlet tube installed. I put a bevel on the inlet tube inside the hull to make it easier to slide the hose onto it in those cramped quarters.

[NativePaul]

That would have been the last one I would have guessed, you said you didn't want a rigger as they are too ugly, then you got a Redbird!