Model Building Tips & Tricks 

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Auto Bilge Pump or Warning Light/Siren

This item is a handy way to guard against your hull taking on water. The original design came from the Bay Area Battle Group.

The circuit can be use to active a pump, warning light or siren. Shown to the left is a flashing LED in a small model tug.

The circuit can be assembled for about $5 with parts from Radio Shack. Click here for wiring diagram

When the copper contacts detect water the circuit is complete.

Servo extension used to wire flashing LED in removable cabin.

In later models I have used a small buzzer. On bright days it is hard to see the led. The buzzer sounds like a smoke alarm and can be heard across the pond. Available at Radio Shack for about $2.

Another option is to buy an auto bilge pump like the Boat Saver by RAM

 Voltage Regulator
Change the voltage on your model
Voltage regulators can be used for lighting or to power accessories off the main battery. The voltage regulator's job is to reduce a fixed voltage and drop it to a constant lower voltage.

The use shown here is in my model freighter "Great Laker."  The model uses a 7.2 volt battery for the main engines. The model also uses a bow thruster. At 7.2 volts the bow thruster ran too fast even with the speed control turned all the way down.

I added a National Semiconductor LM1084 5 amp 3.3 volt voltage regulator inline.  This takes the 7.2 volts and converts it to 3.3 volts.

There is no draw on the battery unless the bow thruster motor is running. The extra 3.9 volts is dissipated as heat so I added a small heat sink from Radio Shack (Cat. No. 276-1368). The bow thruster will now work in both forward and reverse and runs at a much slower, accurate speed.

National Semiconductor makes regulators available in an adjustable version, which can set the output voltage with only two external resistors. They are also available in three fixed voltages: 3.3V, 5.0V and 12.0V. They can handle up to 5 amps and are rated for over 12 volts starting voltage.

The LM1084 and heat sink (right)  wired between the battery before the ESC.

Video of the bow thruster in action using 7.2 volts (4.3 meg)
At this voltage the amount of thrust was not accurate and I was concerned that the amount of vibration would damage the thruster mount.

Another video of bow thruster
running (3.3 volts)  (3.7 meg)

Water Proof Seal

Seal the area around an access hatch on your model boat with Liquid Electrical Tape. This product is easily applied and can be found at any hardware store.

Wire Clips 

Keep your wiring in place with this type of clip.

Available at Radio Shack


There are many sources you can use to add ballast. These weights come in 1/4 oz pieces and are handy for fine tuning a model's draft.

Available at you local hobby shop in the model air plane section.


A simple way to mount items in your hull.  The plastic pieces can be glued to a hull with epoxy.

Radio Shack- 10mm Threaded Stand Off, Catalog #276-1381

When heated the plastic will crumbled leaving a small threaded brass fitting.

Mounted in a hull with epoxy.

A plastic hull may be damaged if the screw is tightened too much. Pop rivets (with the rivet removed for the screw to pass through) add strength to the area where the screw is placed through the hull.

Another view.

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