Building the GT400 Deep V electric Model Boat

GT400 Build Instructions

Contents

The contents of your GT400 pack may vary depending upon what you bought. The standard kit build is with the supplied hardware listed below - and that will be detailed here.

Pre joined and trimmed hull
Plasti-card for radio mounting
Graupner 1970 power unit
AsTec 400 stainless steel rudder set
AsTec MHF20 Speed controller (Optional)
2mm light ply for motor mount
Servo Hardware
Suppression capacitor

Instructions

1. Start by building the Graupner power unit from the instructions supplied - do not fit the prop - keep it safe.

2. Drill a small hole in the rear bottom of the skeg to take the shaft from the power unit - It's best to start small and work up, this will avoid splitting the plastic and allow some room for correcting errors. Test fit the drive set.

3. The Motor mount fits over the nosepiece of the motor alignment housing. Mark the centre line of the mounting blank. Mark a point 5/8" above the bottom and then mark a 8mm dia hole (4mm radius) centred on it. Carefully drill and file out the hole. At 8mm it will be a snug fit over the nosepiece. Put two 1 inch square pieces of plasti-card on the hull bottom so that the mount will sit centrally on them and glue in place with liquid poly (DO NOT GO OVERBOARD WITH THE POLY CEMENT IT WORKS BY MELTING THE PLASTIC!! These are not strictly necessary but will help to spread the motor torque load and stop the hull twisting under load. Place the motor mount squarely over the point it will contact and measure the gap from the bottom to the centre line of the boat keel. Transfer this measurement to the edges of the mount and connect the points to the bottom centre cut the mount just outside these lines and sand to a snug fit. Refit the assembly and when satisfied with the position glue in place. (Superglue or Epoxy)

4. Inside the hull mark a point 35mm in from the transom and on the centre line - this is the position of the rudder. Get two 1 inch square piece of plasti-card and mark the centre point (join the corners across the diagonal where the two lines meet is the centre - but only if the square was square!) on them. Drill a 4.5mm hole at the centre point and open it out to fit the rudder tube (Start small and work up slowly or it will tear. 5mm is just to big for the AsTec rudder units tube). Cut one in half and keep the other safe. At the 35mm point drill a hole 4.5 mm diameter and open it out to a friction fit for the rudder tube (the hull should not distort when the tube is placed upright in the hole.

5. Cut two pieces of plasti-card 2 inches (50mm) long by ¾ inch (20mm) high. Glue these to the inside sides of the hull right at the back and flush with the bottom - they provide the shelf to locate the radio tray. Using the template cut out the radio tray - cut it approximately 1mm too large all round and sand it back to a good fit. It's a bit tricky top get it in but it will bend. The hole in the middle does not need to be accurately cut at this point.

6. WITHOUT GLUING ANYTHING Fit the rudder tube so that it is flush with the bottom of the hull. Fit the radio tray on it's rails. Fit the remaining square of plasti-card over the top of the rudder tube. Insert the rudder in the tube and fit the tiller arm to it.

7. Position your servo making sure that it will fit and that there is room for the hardware. As a guide the servo rod should be positioned so that it is located the same distance from the servo pivot and the rudder post. In order to ensure equal rudder movement he servo arm and the rudder tiller arm should be parallel. As an example my standard GWS servo was fitted in a cut out 1 5/8" (42mm) by 7/8" (22mm) with the cut out running fore and aft and being offset from the centre line by 5/8" (15mm). Remove the tiller arm etc then remove and trim the radio tray for the servo. Reinforce the screw points with off cuts from the piece removed (or a piece of scrap wood or light ply will do just as well) and pre drill for the locating screw. Screw the servo in place and fit the radio tray to the rear of the boat.

8. Re fit the rudder tube, fit the piece of plastic over the top, fit the rudder and tiller arm (at the correct angle and just pinched up at this point). Turn the boat upside down and line the rudder up so that it is vertical in both planes. Glue the top piece of plastic to the radio tray and clamp it to ensure that the rudder post cannot move whilst it sets.

9. When it is all set remove the tiller arm and the rudder. You should be able to see a small mark on the shaft where the tiller arm grub screw fits - a small flat can be filed here so that any burr will not interfere with the removal of the rudder - but wait until the position of the arm is verified. If it won't just slide out carefully file it first until it will remove freely. Do not force the shaft out as that will damage the bearings in the shaft. At this point you can cut the shaft to length - be careful not to bend it - and remove any burrs with a file before you refit it.

10. Ensure that the rudder post is correctly position and glue it in place - glue the two pieces with the half holes in them, round the shaft at the bottom inside the hull to strengthen the join.

11. Connect the servo arm and the tiller arm with the hardware provided. The ball joint connector has a small screw and nut to connect it to the servo arm (or the tiller arm - it's your choice - use whichever suits your installation better), trim the screw after you are satisfied with the install. The servo rod has a 2mm thread at one end which can be screwed in to the ball joint connector, the thread can be trimmed if need be, if you do trim it clean it up afterwards with a small file. Screw the servo rod halfway in to the ball joint connector, measure the length of the rod needed to reach the other hole and keep all components in the right relative positions - then bend it at right angles and trim it to about 3/16" after the bend.

12. Fit the snap link connector over the tiller arm so that the hooked link is on the same side as the servo rod and so that the servo rod can be clipped in to it. Centralise the hole on one in the tiller arm. Drop the bent hole in the tiller arm and clip the link over the servo rod. Now check your servo movement ensuring that there are no binds.

13. Remove the motor from the mount and solder the suppression capacitor across it's terminals - use the supplied sleeve to insulate it's legs. Solder the speed controller to the motor - or if preferred use a plug to connect it. Similarly use a plug that matches your battery pack to connect it to that. The MHF20 has a BEC circuit and will supply the radio with power.

14. Fit the Receiver to the radio tray with your favourite method (We use sticky Velcro. The battery (6 or 7 cell sport Sub C pack - not supplied) will fit down the middle of the boat and can be secured in a similar way. The boat will run very well like this but there is nearly no room for adjustment.

Advanced Processes

Rudder

The boat will run faster if you sharpen the front edge of the rudder - razor sharp is best but if you have children a little blunter might be better for them. The rudder may also be re shaped to give improved performance at higher speeds - If the back lifts in turns trim the top rear of the rudder away at a 45 degree angle. A similar cut at the bottom front is also known to improve turning at speed in some boats.

Centre of Gravity

Moving the centre of gravity of the boat can have a vast effect on performance - with a standard pack there is not much room to change this. Without changing the pack it can be offset to the left (from the rear to counter torque roll and improve handling at high speed - it can look funny at rest and low speeds though. Using two 3 cell stick packs will improve the ability to move the CofG forwards and backwards One stick should be able to move right back to the transom. On 7 cells, try using a set of 3 and a set of 4 - put the 4 on the LHS (from the rear) of the boat to counter torque roll)

Super Detailing

There is plenty of room for super detailing on these models so whether built as a scale boat or a race boat you can have even more fun. If you intend to race please take care over the weight. If not then try making a mast from a Mahogany off cut. Adding details such as mooring bollards and ropes, exhaust pipes, air intakes etc is possible.

Racing

Yes you can race these boats - we did at the Weymouth festival. One was done up as in one of the James Bond Films, Another had an Eeyore driving - neither affected their performance. I drove one with a 480 in it and 1900 mah cells and it was faster than the pure race machines - so it can be done. If you do want to race seriously then watch the weight and tape the hatch down rather than relying on the tight fit.

Whatever you do - do have fun!!

GT400 radio plate template