How to Waterproof RC Car and Boat Electronics: Step-by-Step Guide

Protecting your RC car or boat’s electronics from water, mud, and dust can save you a lot of headache and broken parts. In this guide we’ll show step-by-step how to seal up your receiver, ESC (electronic speed controller), servos, battery leads and other vulnerable parts. We cover two methods: a temporary method using heat-shrink tubing, grease and a sealed box, and a permanent method using conformal coatings (silicone/aerosol coatings). Each method has its pros and cons, so you can pick the one that fits your needs. By the end you’ll also know how to test your electronics after waterproofing and fix common problems.

Which Electronics Must Be Protected

All the water-sensitive components in an RC vehicle should be protected. That usually means:

• Receiver (the radio receiver that takes signals from your transmitter).
• ESC (Speed Controller), which drives the motor.
• Servos (steering, throttle servos etc.).
• Wiring and connectors, including servo lead plugs, battery plugs (Deans, XT60, JST, balance plugs, etc.), and any open wires.
• Battery leads and balance connectors on LiPo batteries.
• Sensor wires (e.g. waterproof temperature sensors, if any).

Using dielectric grease or coatings on these parts can keep water out of the pins and circuit boards. If moisture gets into a receiver or ESC, it can short out the electronics and cause failure. Protecting them is important whether you run RC rock crawlers, off-road buggies in rain, or RC boats.

Figure: A hobby servo (top) and its wires. Servo gearboxes and circuit boards inside (not shown) also need protection from water and dirt.

Preparation: Disassembly, Cleaning, and Labeling

Before applying any waterproofing, disassemble and clean your electronics. Follow these steps:

• Disassemble carefully: Unplug your ESC and servos from the receiver, and remove the receiver or ESC from the chassis. Open any housings or cases if you plan to coat inside.
• Clean with alcohol: Use compressed air and isopropyl (rubbing) alcohol to blow out dust and oil, and wipe down circuit boards. FliteTest notes that boards should be cleaned with alcohol before sealing, or else glue and coatings may not stick. A clean, dry surface is important.
• Label wires: Use masking tape or small labels to mark which wire goes to which servo or battery port. This makes reassembly easy after sealing.
• Inspect parts: Make sure everything is working before you seal it. It’s hard to repair coated electronics. Check motor, servos, and receiver range first, then proceed.

Taking the time to clean and label saves frustration later. Never seal a damp electronic part – moisture trapped under sealant will cause corrosion.

Method A — Temporary/Removable Waterproofing

This method is reversible. It uses common supplies (heat-shrink tubing, dielectric grease, waterproof tape) so you can take parts apart later. It’s great for a quick fix or if you want to test the system often.

Tools & Materials

• Heat-shrink tubing kit (assorted sizes). Use marine-grade or adhesive-lined shrink tubing if possible.
• Dielectric silicone grease (e.g. CRC Marine dielectric grease). This is a non-conductive grease that repels water from contacts.
• Electrical tape or liquid tape (optional) for extra sealing on wires.
• Silicone sealant or petroleum jelly (Vaseline) for sealing box edges/gaskets. For example, an ARRMA RC forum user suggests using Vaseline on the receiver box gasket and cable exits.
• Small plastic box or receiver box: A waterproof project box (or the vehicle’s stock receiver box) with a gasket. You’ll seal the electronics inside this.
• Cotton swabs, alcohol, labels, and basic tools. Clean rags and brushes help prep parts.

Affiliate example products: You may consider an assorted heat-shrink tubing kit, dielectric silicone grease (e.g. CRC Marine Dielectric Grease) and any waterproof tape or silicone sealant (not shown).

Step-by-Step Guide (Temporary Method)

Follow these steps, estimating time for each:

1. Open up components (5–10 min): Remove any covers on servos or the ESC. If you have metal-geared servos, pulling apart the case can let you coat inside. Tip: Make sure to note how gears and potentiometers go before you take them apart.
2. Clean thoroughly (5–10 min): Wipe and blow out dust with compressed air. Swab the circuit board and connectors with isopropyl alcohol to remove grease or moisture. Let dry. Clean surfaces help any sealant stick (FliteTest emphasizes cleaning before sealing).
3. Apply dielectric grease (5 min): Use silicone grease on all exposed connectors: servo-to-receiver plugs, battery plug contacts, ESC input plugs, and especially on the inside of any connector housings. You can pull a servo or ESC plug slightly apart, squirt grease into the opening, and push it back together. The grease will displace any moisture and keep water out. A veteran RC user even packs receivers and ESCs full of grease, leaving no air pockets, so water “can’t get in” . You don’t have to be that thorough, but coat every pin and plug.
4. Slide on heat-shrink (10 min): Measure and cut pieces of heat-shrink tubing so they can cover wire bundles or solder joints. For example, put a piece over the wire group from a servo to the connector, or from the ESC wires to the motor bullets. Slip each piece over the wires and heat it (with a heat gun or lighter) so it tightly wraps the wires. Tip: Use flame-retardant or “heavy duty” heat-shrink if you can, since it’s sturdier in mud/water. Shrink any exposed solder joints to prevent shorts.
5. Seal openings (5 min): If your ESC or receiver box has holes or a removable cover, use silicone caulk or even Vaseline to seal gaps. For instance, put a thin bead of silicone around the lid seam of the receiver box, or smear Vaseline on the gasket. One RC forum post specifically suggests a thin layer of Vaseline on the gasket and cable entries to keep water out . Make sure antenna wires (if any) are still positioned correctly.
6. Place electronics in box (5 min): Put the now-prepped servos, ESC, receiver, etc. into your waterproof box. Make sure wires come out through sealed holes (apply silicone around each hole if needed). You can line the box with foam to prevent parts rattling. Close the lid and secure it. If using a container, you might drill holes just big enough for wires and seal around them.
7. Final check & test (5–10 min): Power on your receiver/ESC outside of water to verify everything still works (servo movement, ESC beeps, receiver LED lights). Do this before driving in rain. If any part didn’t work, you can open up the box and fix it.

These steps are reversible: you can cut off the heat-shrink or scrape out the grease when you need to service the electronics. Method A is good for bashing in puddles or quick wet runs. But remember: this is not 100% guaranteed in heavy immersion. Always rinse off mud after use and let things dry to avoid corrosion.

Method B — Permanent Conformal Coating

For a more waterproof and long-lasting solution, use a conformal coating (sometimes called silicone coats or conformal sprays). This method completely seals the circuit boards and internal parts. It’s best for parts you don’t plan to open frequently. Warning: Conformal coatings are mostly permanent. Removing them takes special strippers or solvents, and often voids warranties. Always check if coating a part will void its warranty before you apply it.

There are three main types of conformal coatings:

• Silicone-based (e.g. MG Chemicals 422C, Cow-Formal). These are very flexible and heat-resistant , and often have a UV-sensitive tracer so you can see if you’ve missed spots. They’re great if the board or wires may flex (rock crawlers).
• Urethane/polyurethane-based. These are extremely durable and chemically resistant . They are excellent for aggressive environments (chemical sprays, saltwater).
• Acrylic-based. These are easy and cheap to apply . Acrylic coatings are fine for modest moisture protection on rigid boards. They’re also often “fast-dry” (like Techspray acrylic).

In general, silicone coatings offer the best all-around moisture protection while remaining flexible .

Steps to Apply Conformal Coating

1. Prepare the electronics (5–15 min): As with Method A, clean the board and components first. Open cases and wash dust off. Make sure boards are completely dry. Mask or unplug anything you don’t want coated (e.g., antenna wiring, connector pins, or large metal heatsinks). Some people put thin tape over PCB connectors or remove plug housings.
2. Apply the first coat: Use a brush/pen or spray-on conformal coating. For example, CowRC’s Cow-Formal silicone comes with a brush applicator .
3. Dry/curing (30 min – 12 hrs): Let the coating cure. Curing time depends on product: MG 422C silicone coating is “fast cure – tack free in about 10 min; dries in 20 min at 65 °C” . You can speed it up with a hot air gun or placing in warm (but not hot) air flow. Check the instructions: some need UV light or warm drying.
4. Flip and re-coat: Once one side is dry, flip the board and coat the other side or any components you missed. Coat connectors’ insides as well, if you didn’t mask them. Again, allow to fully cure. Some coatings fluoresce under UV light when cured, letting you see coverage.
5. Reassemble: Put the electronics back together. You should not try to use hot glue or epoxy on top of conformal coating – the coating itself is the seal. Simply re-attach covers and wires. Leave any components that should not be permanently closed (like battery compartment) uncoated.

Curing Notes and Warnings

• Ventilation: Use conformal coatings in a well-ventilated area. They often have solvents that can be toxic. Wear gloves.
• Heat: Don’t overheat electronics during curing. A hair dryer’s gentle heat is usually enough. Some plastics or wires might warp if too hot.
• Permanent: Once cured, coating is hard to remove. Repairs require special strippers or re-soldering through the coating (some types are “solderable through” ). Work carefully – maybe test with one component first.
• Warranty: Many manufacturers say coating the board voids the warranty, since it’s considered tampering. (Check before you coat expensive gear.)
• Accessories: You can also coat other parts like an ESC’s fan wires or a BEC board. Just make sure power is disconnected when you spray.

Affiliate example product: An example permanent sealant is MG Chemicals 422C Silicone Conformal Coating Pen which is formulated for electronics (flexible, waterproof) and works for RC boards . Some hobbyists also use liquid electrical tape for coating irregular shapes (e.g. around LEDs), which you can find on Amazon as a quick waterproofing paint here.

Testing & Verification

After waterproofing, you must test before any wet run:

• Reconnect and power up: Plug the ESC and servos back into the receiver. Power on and test each function: steering, throttle, etc. A coated ESC will usually emit the normal set-up beeps; calibrate throttle as usual.
• Range test: Turn on your transmitter and receiver with antenna extended. Walk a good distance (30–50 paces) to ensure the receiver still gets signal. A conformal coating on the receiver’s PCB should not affect RF range, but double-check if the antenna was coated by accident.
• Function test: Run the motor briefly and check servos operate without strain. Listen for unusual noises or overheating (especially on ESC).
• Water test (optional): If you’re feeling brave, try a quick dipping test in a bucket (with the battery removed) to see if anything shorts. Don’t submerge completely if unsure – just spray water or submerge for a few seconds and then dry and test again. This reveals leaks. (FliteTest did full submersion tests to show coating power.)

If something doesn’t work after sealing, disassemble that part. It may be a loose connection, overheated wire, or a masked connector. It’s easier to fix now than when the truck is floating in the creek.

Troubleshooting Common Issues

Even after waterproofing, you may face some glitches. Here are typical problems and fixes:

• Motor won’t spin: Check the battery connection and ESC wiring. Sometimes heat-shrink or tape can slip and disconnect a bullet connector or a JR servo lead. Ensure all plugs are fully seated. If using brushed motor ESCs, make sure throttle is calibrated (set throttle to full, turn on ESC then throttle to zero). If motor still doesn’t spin, test it out of the boat/car – the issue might be mechanical (binding) rather than electrical.
• Intermittent signal or lost control: This usually means the receiver or servo wiring has a bad contact. Check all plugs on the receiver (servo ports, battery port). Look for any moisture in servo sockets (clean and re-grease them). Make sure the receiver’s antenna is intact and not shorted by sealant or twisted under tape. A very common fix is to unplug each servo one at a time and test; a bad servo or cable can cause the whole system to drop out.
• Servo stuttering/freezing: If a servo jerks, it might be a power issue. Verify the battery voltage is good, and the ESC’s battery connector is clean. Sometimes silicone grease on a relay or motor connection can slightly insulate it – wipe off grease on power contacts. Also check if the servo itself was over-coated: too much conformal on a servo’s potentiometer board could interfere with its movement. In that case, open the servo, clean off excess coating, and re-grease only the gear (if needed) and seals.
• Electronics overheating: Ensure heat-shrink or coating wasn’t blocking a fan or vent on an ESC. If an ESC runs hotter after coating, maybe add a small fan or heat-sink.
• Persistent corrosion: If corrosion continues, it means moisture is still getting in. Re-check seals (especially the receiver box edges or any cable holes). Consider adding a silica gel pack in the box. After use, remove gear and dry completely to reset the system.

If problems persist, revert some waterproofing. For example, open the sealed box and test electronics in the open air. This helps isolate whether the waterproofing itself caused an issue.

With both methods, routine maintenance is key: after each water run, rinse off salt or mud, blow-dry, and remove any grease buildup. The best waterproofing fails if dirt and corrosion set in over time.

Conclusion

Waterproofing your RC electronics can give you peace of mind when driving in wet or dusty conditions. The temporary method (heat-shrink tubing, grease, sealed box) is quick and easy to reverse, making it good for hobbyists who switch parts often. The permanent method (conformal coating) provides the highest protection and is ideal for dedicated builds, but is harder to remove later. Often, builders use a combination: grease on connectors plus a light conformal coat on PCBs.

Remember the key steps: clean first, apply the sealant or grease carefully, and then test everything before hitting the water. With proper preparation, your receiver, ESC, and servos will stay safe from splashes, mud, and rain. Enjoy your wetter, harder sessions without worry – and know that detailed guides (like those from FliteTest and RC forums ) back up these tips from the hobby community.

References: Verified RC community sources and manufacturer data were used. For example, FliteTest’s “Waterproofing Electronics” tutorial recommends cleaning boards and shows spraying with Corrosion X HD, and notes “epoxy is the best way to seal your ESC” confirm products like MG Chemicals 422C provide a durable, flexible moisture barrier. These methods have been proven in real RC usage.