36″ Twin Prop Catamaran (Assembly Instructions)

Twin Prop

Twin Prop

After recently completing the build of our carbon fibre genesis 900 single motor hull, we decided it was time to tackle a dual prop setup.  One thing we were not happy with the genesis hull was it’s stability at high speed and around corners.  Doing some research online we should a fairly cheap chinese hull that was of simular size and build quality to the TFL genesis but was much wider.

Click on ‘Continue Reading’ below to see the complete build log!

Sourcing the hull locally turned out to be a breeze.  We arein Australia, where we are privileged enough to have a dedicated electric rc boat store who sells just about everything at very reasonable prices (RCBoatBitz.com.au).  We are in no way shape or form affiliaited with them, but we do like promoting businesses who does a good job!

Everything for this build, barring the Turnigy electronics have been sourced from RCBB.

Mounts installed

Ingredients:

  • RCBB 36 Inch Catamaran bare hull.
  • 3/16 Counter rotating drive lines with one piece flex shafts.
  • 110mm 3/16 Stingers.
  • 4214 Props.
  • Alloy motor mounts.
  • Under hull dual water pickup.
  • Large cat rudder, 115mm same as Genesis.
  • Alloy push button hatch locks.
  • Large size water fittings and tubing.
  • 2x Turnigy 2400Kv 3660 motors.
  • 2x Turnigy 180amp speed controllers.

…….

Let’s get started with two photos of the bare hull after is was unpackaged and thrown onto our work bench. The first photo shows the hull with the hatch on and the second shows her insides!

Bare hull (Outside)
Bare hull (Inside)

We take alot of pride in building our boats to the best quality we can, for this reason we always reinforce with multiple layers of fibre glass to ensure that the hull is nice and rigid.  Fingers crossed this extra effort might one day protect the hull in the unfortunate circumstance of us having a crash!

Reinforcing the hull

We prefer to work with fibre glass woven strips instead of the normal sheets you get for larger scale domestic repairs. The strips can be purchased from Bunnings and are the ‘diggers’ branch.

Fibre glass matting

After four layers of extra glass have been applied, we let the resin set for 24 hours!

First layer of fibre glass

For this build we had a few nifty little parts we wanted to try out, here you see a dual under hull water pickup installed thru the floor of the hull.  As this is a catamaran you could argue that the pickup will not see alot of water come thru.  However we beleive at low speed and during turns it will indeed provide additional cooling in line with the dual rudder pickup that will be installed.  For a single motor build, you would place this water pickup at the bottom of the swansons.

Water pickup (Installed)

For our next step we are going to install the servo mount, this is a simple mount that will keep the servo secure. Simply glue her down and your ready to move on..

Servo mount

After a couple beers have been drunk during the first few steps, we forget to take some photos of drilling the holes for the rudder. If your really interested in checking out some holes drilled into the hull, look at our genesis build! (sorry!)

Rudder

Now for the hard part, installed the stingers onto the back of the swansons. Not the easiest job lining up all of the holes but once you get there, you know you have concuquered the hard parts.  We have a little tip for getting the holes lined up which we will document on our next dual prop build!

Stingers

Here is a quick shot of the motors attached to the alloy motor mounts with the water jackets also installed. These are the turnigy 2400kv inrunners.

Motors

Now that the motors are ready to be secured into the hull, it’s time to start lining them up and working out how you would like the balance out the boat.  As we will eventually convert this boat to a 6S lipo setup we have pushed the centre of gravity forward.  This will still give us plenty of room to mount the batteries on the upper deck and the ESC’s infront of the motors in the swansons.

Installing motor mounts

Now that your motors are all aligned, we have the fun part which is bending the stuffing tube! As we only need small bends in this tube, we have elected to use alloy 9/32 tubing.
Allow tubing can generally be bent by hand with no need for heat.  If your using copper, look out for our how-to guide on bending copper stuffing tube in the coming weeks!

We used epoxy putty to secure the stuffing tube to the stingers.

One stuffing tube installed
Both completed

Starting to install the water cooling into the boat, an easy job!  We really like the larger diametre water lines with the anti-kink spring on the outside.

Water inlets

Now it’s time to secure your speed controllers down. We use a simple method of alloy sheeting with copper tubes glued and riveted to the sheet to act as our mounts.
They take no longer than 15 minutes to make and work fantastic, we have found that by lifting the speed controllers off the floor of the hull you are less likely to have issues with small amounts of water seeping into the boat.

Speed controller mounts
Mounts installed