Parachutes can slow/stop an entire ship provided the ship is not too heavy, and that the decent is not too fast. Because of the sudden deceleration caused by a parachute opening, if a ship is not already traveling at a significantly reduced speed, the parachute will likely cause so much force on the ship that it will tear off whatever its attached to. The best ways to fix this is to either slow your decent by other means (engines or drogue chutes), or use a smaller, lighter decent vehicle. Also keep in mind that deploying the parachutes too low will cause them to fully open immediately on deployment, causing a much stronger jolt than if they partially deploy higher up, and then fully deploy at lower altitudes.