How to Complete the “Father and Son” Mission in GTA 5
After the events of previous missions, Franklin arrives at Michael's house. Their brief conversation is interrupted by a phone call from Jimmy. Michael's son is clearly panicking — he reports that he wanted to sell the yacht, but the buyers turned out to be dishonest people.
The yacht was stolen along with him, and now he has barricaded himself in the wheelhouse, not knowing what to do. Michael is furious, but he acts quickly.
He grabs the keys to Amanda's convertible, calls Franklin, and rushes to rescue his son.
Follow the route on the map.
Drive fast but carefully so as not to damage the car, because any damage can not only ruin the condition of the car, but also knock you off your timing for the gold medal.
Catching up with the trailer with the yacht
After a few minutes of driving, you will see a trailer with a yacht. It is moving along the highway at a fairly fast pace. Your task is to catch up with it and approach from behind. Drive the car up to the stern of the yacht, keeping it as level as possible so that Franklin can climb onto the hood and jump onto the boat.
Once you are in the right position, the scene will continue automatically.
Franklin climbs onto the yacht, and the fight begins. One of the kidnappers attacks with his fists.
Don't interfere, just keep driving smoothly behind the trailer. Once Franklin defeats the first enemy, the second one will appear. The second enemy is armed and will start shooting at your car. You need to shoot this enemy.
Use the crosshairs and aim carefully, because the slightest mistake will kill Franklin, which means the mission will fail.
Jimmy is in danger
After both thieves are neutralized, Jimmy climbs out of the cab. He clings to the mast and, when the trailer turns, finds himself suspended above the road. This is a key moment.
As soon as he appears, you have only 10 seconds to drive up to him and catch him in the back seat.
Drive smoothly, don't slow down, and stay strictly in the center of the lane, moving smoothly. As soon as Jimmy is directly above the car, he will jump off himself. If you don't make it in time, he will fall onto the asphalt and the mission will fail.
The last jump
Immediately after rescuing his son, Franklin appears. He is ready to jump off the yacht. You must drive up to the stern again and keep the car steady. Franklin will jump onto the hood and automatically climb inside. 
Do not slow down under any circumstances and avoid sudden maneuvers. This is the last moment before the car starts to break down.
The way to the car service
As soon as Franklin is in the car, the convertible will start to smoke.
Michael swears and says that the yacht is leaving, but there is nothing he can do. He asks Franklin to take the car to Los Santos Customs for repairs, while he calls a taxi and leaves. Now you control Franklin.
Follow the route to the auto repair shop. Try not to hit any cars while driving. If the car is damaged while driving, you will not receive a gold medal. At the auto repair shop, select the “Full Repair” option.
After the repair, leave the shop and head back to Michael's house.
During the trip, Jimmy talks to Franklin, trying to make friends. The hero himself is not particularly enthusiastic, but he does not object. Upon arrival home, park the car at the designated spot.
The mission will end automatically.
How to get a gold medal

To complete the mission 100%, you must fulfill two conditions:
1. Rescue Jimmy within 10 seconds. Immediately after he appears, drive smoothly and quickly. Do not slow down or deviate from the center of the lane under any circumstances.
2. Do not damage Amanda's car. This means no collisions with other cars, curbs, signs, and especially when shooting. The enemy on the yacht will shoot, so act quickly and accurately to prevent him from hitting the hood.