R2 Hobbies 36" Cat - Twin Drive

[Aaron Johnson]

Hey Guys,

For my second scratch build, I decided to go with a cat a little bit wider than my carbon fibre genesis. I am in Australia, where we are privileged enough to have a dedicated electric boat store who sells just about everything at very reasonable prices with some of the best customer service I have experienced (RCBoatBitz.com.au).

Everything for this build, barring the cheap electronics have been sourced from RCBB. I'll throw some proper electronics in from RCBB when they re open next month.

Given that it was the holidays and I had a bit of time up my sleeve, here is a quick blog of my build which I completed over the last few days.

Ingredients:

• R2 Hobbies 36 Inch Cat
• 3/16 Counter rotating drive line with one piece flex shafts.
• 110mm Stingers.
• 4214 Props.
• Alloy motor mounts.
• Under hull dual water pickup.
• Large cat rudder.
• Alloy hatch locks
• Large size water fittings and tubing.
• 2x Turnigy 2400Kv 3660 motors.
• 2x Birdie 200amp ESC (my spec).

[Aaron Johnson]

Straight out of the box and onto the work bench



There is more than enough room to run dual 40mm motors in this beast.



Time to start adding some extra fibre glass to make her more rigid



For the centre of the hull I used a 100mm wide fibre cloth and a 50mm wide for the sides.



Two solid layers of fibre glass applied, pretty happy with the result! It was a 40 degree day so the resin dried within an hour.

[Aaron Johnson]

Nothing like cutting holes into a branch new hull!



Dual under hull water pickup from RCBoatBitz



Epoxy putty to seal down the water pickup and servo mount fitted



Ruder fitted



Stingers all mounted up nice and square

[Aaron Johnson]

Water jackets added to the motors, motors screwed to alloy mounts and 3/16 drive collets ready to go



The birdie ESC's are known for being OK if you take the time to waterproof them and clean up some of the solder points and also attach the heat sinks with decent thermal tape instead of the crap that comes from the factory. I run CorrisonX on all of my RC gear, it does a great job of making stuff water resistant



Let the CorrosionX drip dry overnight, just to be sure.



With this build I'll be running hatch locks, just encase these fail I thought I would water proof everything good and proper! Liquid electric tape, I used this on all my scaling gear until I found corrosionX. Why not combined the two for super water tightness.



Marking up the motors for install.



Playing around with lipo configurations

[Aaron Johnson]

Motors epoxied down and first stuffing tube installed! I used epoxy putty to hold it in place.





Drive lines are now complete!



Starting to plumb her up with large tubing with anti-kink springs



Quick and easy ESC mounts to keep them raised off the floor.

[Aaron Johnson]

ESC mounts lined up and epoxied into place, precision alignment here. One cigarette lighter from the centre hahaha



ESC installed onto the mounts, I use anti slip matting between the ESC and the mount and secure them on with a cable tie

[Aaron Johnson]

Thought I would bench test the electronics!

[meangenesracing]

just checking out your build you sure that water pickup is going to work i would think it would not due to being placed in the center of the hull cat hulls ride on the sponsons. i placed two of these in my twin neu AM avenger cat on the bottom rear of each sponsons. I could be wrong im no expert boat builder. maybe someone else would have some more feedback on this

[Aaron Johnson]

just checking out your build you sure that water pickup is going to work i would think it would not due to being placed in the center of the hull cat hulls ride on the sponsons. i placed two of these in my twin neu AM avenger cat on the bottom rear of each sponsons. I could be wrong im no expert boat builder. maybe someone else would have some more feedback on this

I think you have a fair point to be honest! Although it will likely run pretty wet and as I have placed it towards the back of the boat and it would certainly pickup water at slow speed. Under load and when she is up on plane you might in fact be very correct. I'll monitor temps and see how we go. Worst case I will run a rudder with dual water pick ups to compensate.

Thanks for the feedback :)

[capnswanny]

I have to agree, I don't think your going to get any water flow. If you test like this, make sure you have water coming out on your first pass. If you don't I would bring it in
I run basically the same hull with a single rudder pickup split to each ESC and motor and run cool. I'm using 60A AQ ESC to 36mm 2300Kv spinning x442 props in the lower 50mph range.
http://forums.offshoreelectrics.com/...my-36-quot-Cat
Happy Holidays!

[flraptor07]

I wouldn't even risk it, you're not going to get any water flow where you have the pickup located now. Move it to the bottom of one of the sponsons or get two singles and put one in each sponson. I'd hate to see you burn up some motors and ESCs.

[Aaron Johnson]

I wouldn't even risk it, you're not going to get any water flow where you have the pickup located now. Move it to the bottom of one of the sponsons or get two singles and put one in each sponson. I'd hate to see you burn up some motors and ESCs.

Well I risked it and they suck up water just fine, what a great boat so very happy with it!

Will have to get some footage of it soon, but I can see myself running some bigger motors in it or even 6s each side lol!

[capnswanny]

NICE!
Boat looks really good, look forward to seeing some video!

[dasboata]

Water pickups in the tunnel not going to work , they need to be in the sponsons and they also need some work with a file or dremel to make them work you need to lenghten the hole in there good luck

[kenrid]

Aaron, congratulations on an excellent build thread. Your photos make the build very easy to follow. I agree RCBB is a great place to shop at least in Australia, (so is OSE and Kintec). Good luck with the twin setup. A double challenge. Maybe we will see some more offerings from R2 Hobbies in 2014? I certainly get plenty of marketing messages from them, but I consider their boat offerings are a little immature yet.