Building a ScatCat 26

Below are a sequence of pictures showing the progression on the edge and seam treatment.  The first is the hull after the coat of epoxy mixture has been sanded.  The next is after both the coat of white squadron putty and the auto body glazing compound have been completed.  I follow the epoxy, putty, glazing as they each work on progressively smaller defects.  The last picture shows the sharp and blended in edge with a little primer applied.  The grey primer helps highlight any defects that might need a little touchup.

SECTION 5: Prep the Hatch

With the hull joined you will need to do a little trim work on the hatch cover. First measure the hull opening width in two places, front and back . Transfer those to the hatch and cut it to the proper width.  Now do the same for the length, measure right and left sides of the opening and transfer those the hatch, cut the trailing edge.

BBY also sells a hatch scoop, its made of carbon fiber and can be attached with CA to the hatch.  It was to good looking not to have on this boat so I ordered one and attached it.

Section 6: Installing the Running Hardware

Now its time to install the motor mount, servo mount, rudder, strut and stuffing tube.  I like to start with the motor mount, most manufactures will tell you where to position it in the boat, normally a measurement from the transom.  (Photo 31)

Motor Mount

I like to bolt the motor mount to a block of wood which I then epoxy into the hull. This allows for removal of the metal motor mount should you decide to change to a new style motor or mount in the future.  Sometimes the block of wood is a simple as thin plywood with two blind nuts attached.  In this hull the V shape bottom really required a V block below the plywood so the proper support was given.  I cut a piece of paper to the hull bottom shape and sanded a block to fit. (Photos 29-30).  Once done just mount the motor mount to the block and epoxy it into the hull. I'll use the plywood to the left and right of the motor mount to attach my Rx and ESC.

Stuffing Tube

Next on the list is to install the stuffing tube into the hull.  There are two articles on this site to help you out (Installing a Stuffing Tube and Tube Bending). I like to start by mounting the strut on the transom so that I have the height and length of the stuffing tube roughly known. (Photo 32). With the strut mounted you can determine the distance from the transom along the centerline where you cut the slot in the bottom of the boat, this is where the stuffing tube will enter.  You want to minimize the bends in the tube so you don't have any driveline binding (Photo 33). The vendor of the hull may tell you where to locate the slot or you can bend the tube so its flows nicely and determine the spot yourself.

With the slot location determined and cut you can now epoxy the stuffing tube in place.  Install the motor, tube and strut so I know everything is correctly located, moving a stuffing tube after its in place is not fun.  First tape the bottom of the hull where the tube exits, this is so the epoxy you are about to add does not drip through.  For adding the epoxy I like to make a small mote to both keep the epoxy in place while it dries and so the hardened epoxy has a finished shape and is not just a blob inside the hull. (Photos 34-35).  To do this I just use some foam tape but there are lots of options to accomplish this task.

Servo

Next its time to mount the servo, you want to mount it so the horn, tie rod  and rudder arm are as in-line as possible.  To do so you must have your rudder mounted to the transom.  The rudder location is determined by either the running hardware or based off the recommendation of the boat manufacture.  In this case the rudder and strut bracket are the same part so its location is set by the hardware.

With the rudder mounted, drill a hole in the transom in line with the rudder arm (or in spot designated by hardware) so you can bring the tie rod through into the hull.  Attach the tie rod to the rudder and locate the servo front/back side/side in the hull.  Look for a location towards the rear that will minimize bends and not be in the way of batteries and wiring.  Once I settle on a location, I like to bolt the servo to a metal bracket, or screw it on to blocks of wood, which I then epoxy into the hull.  You can also use Velcro or double sided servo tape to mount the servo but I find it gives to much under load which causes poor or sloppy turning response (Photo 36). 

Once its mounted, attach the tie rod to the servo horn and give it a test.  I attach the servo to the receiver and test it for free motion (Photo 37).  You might have to increase the size of the hole in the transom to prevent binding during the servo motion. The transom hole is sealed with a rubber boot that should come with the hardware kit. (Photo 38)

Section 7: Installing the Water Cooling

For this Hull I decided to do something a little different than I had done on my previous boats.  Normally I use either a rudder with an integrated water pickup or a brass tube water pickup that scoops the water in from the prop spray. 

I installed a water pickup on the bottom of each sponson, approximately an inch from the rear of the sponson.  The pickups have an inlet and an outlet so you can both bring the water in and discharge it with the same part.  I decided to only use the inlet portion so that I could run the water discharge though a set of exhaust pipes on the back of the boat.  I simply plugged the built in discharge port since I was not going to use it.  I used one of my inlets for the ESC water loop and one for the brush cooling loop.

To make the exhaust I used some carbon fiber tubing that was large enough to allowed me to slide my silicon tube inside.  I epoxied the silicon tube inside the carbon tube (Photo 39).  I also decided on total of 4 exhaust pipes on the rear of the boat, to me that looked the best, even though I only used two for the water discharge.  To install the exhaust I located and drilled four the holes and CA'ed the tubes in place (Photo 40).

Section 7: Paint

There are lots of articles on how to paint hulls so I'll be brief in this section.  With the hull assembled and all the hardware in place its time to lay some paint down on the hull.  Start by removing all the hardware since you don't want to paint that.  You then have to choose your scheme, the choices are endless and limited only by your imagination. 

I decided on a three color design with red, white and yellow.  Looking though my various paint masks I also found a set of spider web masks which I incorporated into the design.  I sketched out what I wanted on a piece of paper and then began the process.

Start by cleaning and drying the hull, you want all the dust and oils from the build process removed.  I then use a white primer and place two coats down.  I sand the primer coats with 0000 steel wool.  Next I start with the lightest color and work towards the darkest since dark covers light colors very well but the reverse it not true

I placed two coats of white paint down and when dry applied the spider masks and masked of the areas for the red and yellow areas.  I then applied the red and yellow paints.

When everything was dry I moved my attention to the hatch cover.  First I masked the entire cover except for the windshield area which I then sprayed with a silver color.  I then removed all the tape from the hatch and used black pin striping to outline the windshield.

When this was all dry I gave the hull a light sanding with 0000 steel wool and applied 2-3 coats of clear.  Now the finish before the clear was very shiny but I have found that the hatch tape lifts the color more often then it does lift a clear coat, your mileage may vary. (Photos 41-43)