One essential activity of the boater that distinguishes the experienced boater from the novice is trailering and launching. The skills require practice, with practice comes proficiency and the development of a routine. Once a routine is established, maintenance problems are reduced to a minimum and safety concerns are minimal.
Make sure your rig is secure before towing. Check the hitch ball and/or slug to make sure they are tight. Walk around the rig and make sure all straps are tight and secure, the lower unit is up, and wheel chocks or other obstructions are clear.
Back the tow vehicle up to the trailer. If you have help, have your partner stand beside the trailer tongue to help with alignment on the hitch ball. One system that works well is to have your partner hold a thumbs up when the hitch ball is in line with the tongue. If off to left or right, point in the direction the tow vehicle needs to go to get on line. If necessary, raise the tongue with the jack wheel to clear the ball.
When the tongue is on the ball, close the spring lock that keeps the coupler secure on the ball and put the hitch pin or bolt in so it can't pop off. The rig may need to be pulled forward for the tongue to set fully down on the ball. Raise the jack wheel so it is out of the way.
Hook the chains diagonally across (left to right, right to left) to the tow vehicle. If this part of the hitch system fails, the idea is for the chains to catch the tongue to keep it from driving into the ground. Hook the chain for the surge brake system to the tow vehicle.
Connect the lights and make sure they work. Check running, brake, turn signals, and emergency flasher lights.
Check to make sure that the winch cable and safety chain are secured tightly to the boat.
Pull off to the side in an area to prepare the boat for launch. Make sure vehicle and rig are not blocking the launch area or approaches.
Load personal gear into the boat. Put gear from the boat (canvas cover, straps, etc.) into the tow vehicle.
Turn the blower on to ventilate the bilge area. Open the engine compartment to help the process. Use your nose to smell for fumes; nothing works better than your sense of smell for detecting the odor of gasoline.
Put fenders out where appropriate to protect the boat when it is being launched. Prepare any lines that will help tie the boat off once it's in the water.
Check the lower unit to make sure the gear oil is topped off. If the oil is foamy, water is mixed with the oil. The oil needs to be replaced and gaskets replaced on both the fill and air vent holes. If the boat is an inboard outdrive and the lower unit is down, raise it before moving the trailer.
Put the drain plug in. If it is already in, check to make sure it is tightly in place.
Approach the ramp and back your trailer to the edge of the water. If you have two people, put one on board to help the driver judge when the trailer is in the right depth of water.
Unplug the lights.
Remove the straps that hold the boat on the trailer at the stern and/or amidships area of the boat if you have not done so already. Store in the boat for easy access when pulling the boat out. Do not remove the winch and safety chain hooks on the bow eye until the boat and trailer are in the water.
Back the trailer into the water. If there is someone on board, they can signal when to stop with the horn. A good rule of thumb is to back the trailer in until the trailer wheel hubs are just above the surface of the water. This might not work depending on the gradient of the ramp and how quickly it drops off. All ramps are different, so trial and error will play a big part in learning the ramps in your area. Mechanics who work on trailer brakes recommend that trailer hubs never be submerged in saltwater. If they are dunked, make sure they are rinsed off with fresh water at the end of the day and expect major brake work a minimum of every two years. Chock the wheels of the tow vehicle.
Lower the inboard/outdrive. Check clearance for the lower unit to avoid damage. Start the boat and warm it up for two to five minutes. Remove the winch hook from the bow eye, release the lock or ratchet and remove the hooks. If the boat doesn't roll off the trailer, it will need to be put in forward gear to take tension off the cable. Put the throttle in forward gear when the engine is warmed up with just enough power to take tension off the cable. The partner can take the hook off and give the 'O.K.' hand signal to the operator. Communication between partners is essential to avoid injuries. Sometimes the weight of the boat is not enough to pull the cable out. Sometimes the gradient of the ramp is not steep enough for the boat to roll off. Put the boat in reverse, release the lock or ratchet, and back off two or three feet. Once the cable pays out, put the boat in neutral and remove the hook. It may help to throttle forward a short distance to slacken the cable.
Remove the hook and back the boat away from the ramp to a waiting area. Keep the boat clear of the launch/retrieval area so other boaters can use the ramp.
On a regular basis, nuts and bolts should be checked to make sure they are tight. Tires should be checked regularly and rotated. If your trailer is big, consider having it x-rayed once every 2-3 years for structural damage.
Watch this video on launching and retrieiving a boat.